Long-Term Results of Mandibular Reconstruction of Continuity Defects with Fibula Free Flap and Implant-Borne Dental Rehabilitation Wei Fang, MSc, BDS1/Yan-pu Liu, DDS, PhD2/Qin Ma, DDS, MD3/ Bao-Lin Liu, PhD2/Yimin Zhao, MD, DDS, PhD4 Purpose: This study evaluated the retrospective outcomes of implant-borne dental rehabilitation in patients with mandibular defects reconstructed with a fibula free flap. Materials and Methods: Patients with segmental mandibular defects were enrolled in this cohort study. Defects in these patients were caused by oral neoplasm, trauma, and osteoradionecrosis. The patients were treated with a fibula free flap procedure and dental implant–borne prostheses between 1988 and 2010. Clinical and radiographic data were evaluated; KaplanMeier survival analysis and Poisson regression analysis were used to evaluate implant survival parameters. The statistical significance (α = .05) of the results was determined. Results: Seventy-four patients were selected in this study. All patients were available for continuous follow-up. Nine patients (12.1%) developed fibular graft complications postoperatively: 3 in donor sites and 6 in recipient sites. One hundred ninety-two implants were inserted, and 18 implants failed (9.3%). Overall implant survival in patients was 90.1%, 83.1%, and 69.3% after 5, 10, and 20 years, respectively. In 152 implants, probing depth (PD) ranged from 2 to 3 mm. In 31 implants, PD was greater than 5 mm. In 9 implants, PD was greater than 7 mm. The highest implant failure rates were expected for men (odds ratio [OR] = 2.948; 95% confidence interval [CI], 1.10 to 7.85; P = .031), patients receiving primary fibula free flap reconstruction (OR = 3.696; 95% CI, 1.16 to 11.73; P = .027), and patients receiving radiotherapy (OR = 5.269; 95% CI, 1.40 to 19.7; P = .014). Conclusion: Fibula free flap procedures and implant-borne prostheses proved to be reliable approaches for rehabilitation of mandibular defects and oral function. The overall postoperative fibula free flap and peri-implant complication rates proved to be low. Regular follow-up visits and proper oral hygiene maintenance contributed to the long-term successful treatments. Int J Oral Maxillofac Implants 2015;30:169–178. doi: 10.11607/jomi.3606 Key words: dental implant, fibula free flap, follow-up studies
1Resident,
State Key Laboratory of Military Stomatology, Departments of Implant Dentistry and Oral and Maxillofacial Surgery, School of Stomatology, The Fourth Military Medical University, Xi’an, China. 2Professor, State Key Laboratory of Military Stomatology, Department of Oral and Maxillofacial Surgery, School of Stomatology, The Fourth Military Medical University, Xi’an, China. 3 Professor, State Key Laboratory of Military Stomatology, Department of Oral and Maxillofacial Surgery, School of Stomatology, The Fourth Military Medical University, Xi’an, China. 4Professor, State Key Laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an, China. Wei Fang and Yan-pu Liu contributed equally to this work. Correspondence to: Professor Yimin Zhao, School of Stomatology, Fourth Military Medical University, 145 W Changle Rd, Xian, 710032, China. Fax: +86-29-847-76231. Email: [email protected] ©2015 by Quintessence Publishing Co Inc.
E
xtensive neoplasm resections and trauma in the head and neck region often result in facial bone disfiguration and soft tissue deformities.1 Problems arising from these defects include unesthetic facial contours and compromised oral functions, such as speech, mastication, and swallowing. Advances in microsurgical techniques have brought about significant improvements in oral functional rehabilitation. Vascularized composite autogenous bone grafts offer great potential to restore bone continuity and soft tissue integrity.2–4 The bone flaps can be transplanted with a muscle and skin paddle, which allows the simultaneous reconstruction of both hard and soft tissue with esthetic and functional outcomes that are acceptable to clinicians and patients. A large number of composite bone flaps have been introduced, such as radius, scapula, thoracic rib, iliac crest, and fibula.5,6 Of note, the fibula free flap has demonstrated high reliability and versatility for restoring segmental mandibular defects. The length of harvested fibula free flaps is up The International Journal of Oral & Maxillofacial Implants 169
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Fang et al
Treatment Planning
Fig 1 Virtual implant insertion and tooth arrangement using CAD software.
to 25 to 27 cm, providing a long pedicle to be osteotomized for mandibular defects of almost any length and is especially suitable for defects of more than 6 cm. Fibula free flaps can be used as osteomyocutaneous or osteomuscular flaps. The medullar and periosteal vascularization allows the bone graft to be shaped to an ideal morphologic fit to restore the continuity of the mandible.7 Frodel et al reported that a fibula free flap was capable of accommodating 10-mm implants, taking advantage of bicortical implant-bone anchorage.8 Some authors have reported long-term results of implants placed into a fibula free flap, notably Gbara et al in a 20-year follow-up study and Ferrari et al in a mean 10-year follow-up study.9,10 Despite advances in microsurgical reconstruction approaches, implant-borne rehabilitation on reconstructed mandibles is still a challenge. Adverse conditions include shallow vestibule, few or no residual teeth, bulky and mobile flap, considerable vertical height, and fragile oral mucosa.11,12 The purpose of this study is to review the authors’ experience with fibula free flaps and dental implant-borne rehabilitation for mandibular reconstruction over the past 20 years.
MATERIALS AND METHODS Patient Data
Between 1988 and 2010, patients underwent mandibular reconstruction with fibula free flaps followed by dental implant–borne rehabilitation in the Department of Oral and Maxillofacial Surgery and the Department of Implant Dentistry, Third Affiliated Hospital, Fourth Military Medical University, Xi’an and were enrolled in this retrospective study. Ethical approval was obtained from the Ethics Committee of the university.
Dental rehabilitation of mandibular defects requires comprehensive and multidisciplinary planning prior to surgery. In the present study, treatment planning was performed with the collaboration of maxillofacial surgeons, implant dentists, physicians, and experts in other specialties. On the patient’s initial visit, the intraoral status was examined and recorded, including current defects, prostheses, occlusal relationships, soft tissue irritation, tongue mobility, and residual dentition. Because mandibular defects often result in unesthetic and asymmetric contours, postoperative deviation of the mandible was taken into consideration. After the intraoral examination, radiographic evaluations were performed, including panoramic radiographs and spiral computed tomography (CT). A study cast was mounted in a mean value articulator, followed by a diagnostic wax-up. In some cases, a provisional denture incorporating radiopaque material (gutta percha) was fabricated to mark the corresponding implant sites. Surgical and prosthetic plans were analyzed on the study casts and by means of measurements on the panoramic radiographs. Computer-aided design (CAD) software (Mimics 10.01, SimPlant Pro 11.03, Materialise Software NV) facilitated virtual bone graft and implant insertions (Fig 1).
Primary Defects and Fibula Free Flap Reconstruction Surgery
Positions of mandibular defect sites were classified as lateral, anterior, anterolateral, and lateroanterolateral. The osseous defects were classified by Smolka as Class I to III according to the extent and number of osteotomies needed for the fibula. Class I defects had no osteotomy, Class II had one osteotomy, and Class III had two or more osteotomies. The extent of soft tissue defects was categorized into groups A to D as proposed by Shpitzer et al and modified by Smolka et al.13,14 For the operation, the patient was under general anesthesia in dorsal recumbency. The fibula free flap was usually harvested using a two-team approach in which the flap dissection and preparation of the recipient bed were performed simultaneously. The bony stumps of the primary defects were fully exposed to the buccal and lingual sides. Bone blocks were shaped according to the defect morphology before being affixed to the residual bone with titanium reconstruction plates. The vascularized graft was anastomosed to the facial or superior thyroid arteries and veins.
Dental Implant Insertion
Dental implants were placed after fibula free flap reconstruction. Prophylactic antibiotics were given 30 minutes prior to surgery and for 3 days postoperatively, usually 500 mg of ornidazole. The stage-one
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Fang et al
implant surgeries were performed by experienced surgeons, following the instructions of the implant manufacturer. Patients were required to visit the clinic the day after surgery to assess the wound. Stitches were removed 10 days postoperatively.
Keratinized Soft Tissue Grafting and Vestibuloplasty
Sufficient keratinized soft tissue around the dental implant plays an essential role in the long-term success of implant-borne prostheses. In mandible-reconstructed patients, loss of keratinized tissue and vestibular depth can compromise the dental rehabilitation and oral hygiene access. Keratinized soft tissue grafting with vestibuloplasty was performed accordingly. The submerged grafting technique was utilized as previously reported.15 In this technique, the buccal and lingual sides of the flap were elevated supraperiosteally. The 0.02-inch-thick split-thickness skin graft (STSG) was harvested with the required dimensions. After inserting the implant, the STSG was placed supraperiosteally with its margins sutured to the periosteum (Fig 2); then, the flap was closed with interrupted sutures. After a 1-month healing period, vestibuloplasty was performed. Reentry to the STSG was achieved by elevating the buccal and lingual flaps. The buccal and lingual flaps were trimmed and secured with tight sutures to the underlying periosteum at a more apical level to obtain an ideal vestibule position. Iodoform gauze was pressed against the newly formed vestibule for 2 weeks to stabilize its position. After 2 weeks, an impression was taken using hydrophilic polyvinyl siloxane (DMG Dental-Material) with an open or closed custom-tray impression technique. The final prostheses were delivered 10 days thereafter.
Postoperative Follow-up
Once implant-borne prostheses were placed, instructions for hygiene maintenance were given to the patients as follows: (1) Cotton buds moistened in 50:50 hydrogen peroxide:saline were to be used to remove debris from around the transmucosal abutment cylinders; (2) an interproximal toothbrush with soft bristles was to be used to clean superior aspects of the transmucosal abutment cylinders. The follow-up protocol was established with standardized evaluations, including radiographic data, clinical examination, and patient review. The success of implant osseointegration was assessed according to the standard proposed by Albrektsson: an absence of persistent pain, mobility, or radiolucency around the implant, and bone resorption of no more than 1.5 mm in the first year of prosthetic loading and 0.2 mm in subsequent years.16 The patients were examined radiographically and clinically at the following
Fig 2 The STSG was perforated and then secured with titanium screws. The margin of the STSG was sutured at the vestibule position on the buccal and lingual sides.
time points: 1 day after implant placement (stage-one surgery), immediately after screw uncovering (stagetwo surgery) and prosthesis delivery, at the 6-month recall after treatment, and at annual visits thereafter. The mesial and distal bone absorption was measured on the panoramic radiograph from the implant shoulder to the coronal bone-to-implant contact (BIC) surface. The initial measurement was performed 1 day after implant placement and served as the baseline for future comparisons. Pocket depth (PD) and bleeding on probing (BOP) were also examined and recorded at four sites on the implant (mesiobuccal, mesiolingual, distobuccal, and distolingual). A questionnaire was administered to patients 1 year postoperatively to review their experience with the dental rehabilitation using the Oral Health Impact Profile–14 (OHIP-14) form, which uses 14 items to evaluate seven categories of oral function and subjective perceptions, including physical pain, psychologic discomfort, physical disability, psychologic disability, social disability, and handicap. For every question on the OHIP-14 form, subjects were asked how frequently they had experienced impact regarding that particular item in the preceding 12 months using a 5-point scale coded 4 = very often, 3 = fairly often, 2 = occasionally, 1 = hardly ever, and 0 = never.17,18
Statistical Analysis
Implant survival was analyzed using Kaplan-Meier estimates. The survival curves of irradiated and nonirradiated subjects were compared using a log-rank test. A Poisson regression model was calculated to predict items that significantly contributed to the loss of implants. The Poisson regression analysis took into consideration the presence of multiple implants in the same individual. Implant loss per patient was taken as The International Journal of Oral & Maxillofacial Implants 171
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Fang et al
Table 1 Patient General Information Characteristics Age (y)
No. of patients
Table 2 Tumor Location and Staging for Cancer Patients %
< 30 30–65 > 65
10 48 16
13.5 64.9 21.6
Female Male
13 61
17.6 82.4
Defect cause Oral malignancies Oral benign tumors Trauma Osteoradionecrosis
47 4 18 5
63.5 5.5 24.3 6.7
Radiotherapy Yes No
9 65
12.2 87.8
Sex
the dependent variable, and the Poisson’s regression with a logarithmic link-function and total implants placed per patient was taken as an offset variable. The statistical significance (α = .05) of the results was determined. Statistical analyses were performed with SPSS software, version 16.0 for Windows (SPSS).
RESULTS One hundred twenty-six patients underwent reconstruction of the mandible with a fibula free graft followed by the insertion of endosseous dental implants. Of the subjects who completed the dental rehabilitation, 74 patients were enrolled in this retrospective study (61 men and 13 women; age range, 19 to 75 years; mean, 47 years). Nine patients received radiotherapy in the head and neck region (dose range, 40 to 55 Gy). The radiotherapy was begun 3 to 4 weeks after primary tumor resection. Patient characteristics are presented in Tables 1 and 2.
Primary Defects and Fibula Free Flap Reconstruction Surgery
All defects in this study were Class II (63 cases) or Class III (11 cases). The extent of soft tissue defects is shown in Table 3. The length of the mandibular defects in this study varied from 7 to 12 cm. Both primary and secondary bony reconstruction techniques were utilized. In 12 patients, fibula free flap reconstruction was performed with ablation of the affected bone segments at the same time (primary reconstruction). Sixth-two patients underwent secondary lesion ablation. The defects were maintained by titanium reconstruction plates. Delayed fibula free flap reconstruction (secondary reconstruction) was performed 6 to 26 months postoperatively, depending on the dimensions of the defect and whether the recipient had been irradiated. The average transplanted fibula length was 11.6 cm (range, 9 to 15 cm), with skin paddle dimension of
Patient age (y)
Sex
Primary tumor
Stage
Total dose (Gy)
79
Female
Base of tongue
T3N1
51
58
Male
Mandibular gingiva
T1N0
NA 43
66
Male
Floor of mouth
T2N0
48
Male
Tongue
T3N2
55
50
Female
Mandibular gingiva
T1N0
NA
46
Male
Mandibular gingiva
T2N0
NA
42
Male
Tongue/floor of mouth
T1N0
NA
55
Female
Mandibular gingiva
T1N0
NA
67
Male
Tongue
T1N0
NA
58
Male
Tongue
T2N0
40
51
Male
Mandibular gingiva
T2N1
NA
62
Male
Mandibular gingiva
T4N1
46
59
Female
Mandibular gingiva
T1N0
NA
64
Male
Oropharynx
T2N0
NA
47
Male
Mandibular gingiva
T1N0
NA
61
Male
Mandibular gingiva
T2N0
49
53
Male
Mandibular gingiva
T1N0
NA
54
Male
Mandibular gingiva
T2N0
NA
41
Male
Tongue
T1N0
NA
62
Male
Mandibular gingiva
T3N1
47
49
Female
Tongue
T1N0
NA
44
Male
Tongue
T1N0
NA
47
Female
Mandibular gingiva
T2N0
NA
63
Male
Mandibular gingiva
T1N0
NA
50
Male
Oropharynx
T1N0
NA
55
Male
Mandibular gingiva
T1N0
NA
58
Male
Mandibular gingiva
T3N2
53
47
Male
Tongue
T1N0
NA
41
Male
Floor of mouth/tongue
T2N0
NA
39
Male
Mandibular gingiva
T1N0
NA
54
Male
Mandibular gingiva
T1N0
NA
59
Male
Mandibular gingiva
T1N0
NA
58
Male
Floor of mouth
T2N0
NA
69
Female
Mandibular gingiva
T1N0
NA
72
Male
Mandibular gingiva
T1N0
NA
75
Male
Tongue
T1N0
NA
56
Female
Mandibular gingiva
T1N0
NA
52
Male
Floor of mouth
T2N0
NA
68
Male
Mandibular gingiva
T1N0
NA
61
Male
Mandibular gingiva
T1N0
NA
74
Male
Floor of mouth
T1N0
NA
53
Male
Mandibular gingiva
T1N0
NA
46
Male
Mandibular gingiva
T1N0
NA
55
Male
Tongue
T3N2
42
52
Male
Tongue
T1N0
NA
46
Male
Floor of mouth
T1N0
NA
48
Male
Mandibular gingiva
T2N0
NA
NA = not applicable.
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Fang et al
Table 3 Soft Tissue Deficiency Classification* Defect extension
No. of patients
0.8
A
Lateral mandibular gingiva and mouth floor
51
B
Lateral mandibular gingiva, mouth floor, and part of tongue
13
C
Anterior mandibular gingiva and mouth floor
6
D
Oropharyngeal soft tissue including parts of the tonsil and parts of the base tongue
4
*As proposed by Spitzer et al,14 1997 and modified by Smolka et al,13 2008.
Follow-up (y)
No. of patients
Mean
SD
Bone resorption Mean
Treatment No radiotherapy Radiotherapy No radiotherapycensored Radiotherapycensored
0.6 0.4 0.2 0.0
Table 4 Peri-Implant Pocket Depths and Bone Resorption at Follow-up Pocket depth
Cumulative survival
Group
1.0
SD
1
74
3.17
1.21
0.88
0.51
5
54
3.41
1.05
1.20
0.49
10
32
3.29
0.98
1.48
0.56
15
24
3.32
0.70
1.76
0.50
20
9
3.58
0.54
1.94
0.20
5.7 × 2.9 cm (range, 2.5 × 3 cm to 17 × 5 cm). The vascularized graft was anastomosed to the facial arteries and veins. In three patients, the facial arteries were too fragile for vascular anastomosis. The fibular artery was anastomosed with the superior thyroid artery. In 65 patients, the fibula free flap was uneventful postoperatively. Impaired ankle function in the donor site was observed in three patients. One patient presented with ankle stiffness, and two patients were diagnosed with ankle instability based on the Ankle-Hindfoot Scale and radiographic manifestations. The ankle function of two patients was considerably improved within 6 months postoperatively. One patient continued to present ankle instability during follow-up. Six patients developed complications in the fibula free flap recipient site. Two patients presented full or partial flap failures; wound infections were observed in four patients. One subject presented wound dehiscence 1 day postoperatively. In the revision surgery, the grafted fibula was perforated with a round bur to induce the blood supply. The wound healed eventually after 10 days.
Implant Survival and Oral Function Evaluation
Dental implants were placed 8 to 17 months (mean, 13.5 months) after fibula free flap reconstruction. The implants were placed in a two-stage surgery protocol. All implants were inserted using the submerged
0.0
5.0
10.0
15.0
20.0
25.0
Years to the first implant failure Fig 3 Kaplan-Meier survival analysis for implants placed in reconstructed mandibles. The diagram shows the survival of all implants placed in irradiated and nonirradiated patients during the observation period.
technique. The following implant systems were used: Brånemark (Nobel Biocare), Straumann SLA (Straumann), and MDIC (MDIC Medical). Seventy-four patients received 192 implants (57 Brånemark, 92 MDIC, 43 Straumann SLA). The average implant length was 11.5 mm (range, 8 to 13 mm). The average number of implants placed per patient was five (range, two to nine). The average time between the implant placement (stage-one surgery) and screw uncovering (stage-two surgery) was 7.5 months (range, 5 to 11.4 months). A total of 18 implants had failed at the time of the investigation: 12 implants were lost before prosthetic loading (6.2%); 6 implants were lost during follow-up observation (3.1%). Thirteen failed implants were replaced and successfully reosseointegrated. Additionally, 5 implants (2.6%) osseointegrated successfully but were rendered useless owing to unfavorable positioning for prosthetic retention. Sleeping implants were allowed to remain in situ. The overall implant survival rates in patients were 90.1%, 83.1%, and 69.3% after 5, 10, and 20 years, respectively (Fig 3). The Kaplan-Meier curve presented the effect of radiotherapy on implant osseointegration. For irradiated patients, the implant survival rates were 87.5%, 75%, and 50%, respectively. In the nonirradiated patients, there was sufficient evidence from the Kaplan-Meier survival curves of a difference in the time to first implant failure (log-rank test, 4.35; P = .03). Alterations of the crestal bone levels and pocket depths of dental implants are shown in Table 4. These values corresponded to the radiographic findings. The distribution of responses to the OHIP-14 items is presented in Table 5, which shows that most of the subjects rarely reported having had problems 1 year postoperatively The International Journal of Oral & Maxillofacial Implants 173
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Fang et al
Table 5 Distribution of OHIP-14 Items 1 Year After Dental Rehabilitation Distribution of responses (%)* Impact item
0
1
2
3
4
Mean
SE
OH1
How often in the last year have you had problems with your teeth, mouth, or dentures?
19.6
23.9
26.1
21.7
8.7
1.76
0.184
OH2
Have you had trouble pronouncing any words because of problems with your teeth, mouth, or dentures?
31.8
22.7
20.5
15.9
9.1
1.48
0.202
OH3
Have you had painful aching in your mouth?
44.2
20.9
16.3
7.0
11.6
1.21
0.212
OH4
Have you found it uncomfortable to eat any foods because of problems with your teeth, mouth, or dentures?
28.9
33.3
20.0
11.1
6.7
1.33
0.180
OH5
Have you felt self-conscious because of problems with your teeth, mouth, or dentures?
31.8
27.3
22.7
13.6
4.5
1.32
0.181
OH6
Have you felt tense because of problems with your teeth, mouth, or dentures?
26.1
50.0
15.2
2.2
6.5
1.13
0.154
OH7
Has your diet been unsatisfactory because of problems with your teeth, mouth, or dentures?
25.6
32.6
20.9
9.3
11.6
1.49
0.198
OH8
Have you had to interrupt meals because of problems with your teeth, mouth, or dentures?
45.7
30.4
10.9
6.5
6.5
0.98
0.177
OH9
Have you found it difficult to relax because of problems with your teeth, mouth, or dentures?
26.2
35.7
19.0
16.7
2.4
1.33
0.173
OH10
Have you been a bit embarrassed because of problems with your teeth, mouth, or dentures?
25.0
40.9
18.2
11.4
4.5
1.30
0.168
OH11
Have you been a bit irritable with other people because of problems with your teeth, mouth, or dentures?
9.3
34.9
30.2
16.3
9.3
1.81
0.171
OH12
Have you had difficulty doing your usual jobs because of problems with your teeth, mouth, or dentures?
15.6
40.0
26.7
4.4
13.3
1.60
0.181
OH13
Have you felt that life in general was less satisfying because of problems with your teeth, mouth, or dentures?
10.9
32.6
28.3
15.2
13.0
1.87
0.177
OH14
Have you been totally unable to function because of problems with your teeth, mouth, or dentures?
13.6
38.6
27.3
9.1
11.4
1.66
0.178
*0 = never; 1 = hardly ever; 2 = occasionally; 3 = very often; 4 = fairly often.
vestibuloplasty. There were two types of keratinized soft tissue donor sites: palatal grafts and STSGs. In this study, a palatal graft was used for four patients. An STSG, which provided larger tissue dimensions, was used for 22 patients. Soft tissue grafting and vestibuloplasty were performed in the second-stage implant surgery. In eight patients who underwent the STSG procedure, the submerged grafting technique was utilized.
Prosthetic Rehabilitation and Complications
Fig 4 Intraoral view of telescopic abutments. Note the smooth and immobile soft tissue around the implants after skin grafting and vestibuloplasty procedures.
on all items. There were generally low percentages of patients reporting that they had problems very often in the first year of follow-up.
Keratinized Soft Tissue Grafting
In this retrospective investigation, 26 patients (35.1%) underwent keratinized soft tissue grafting with
Twenty-seven subjects received screw-retained porcelain-fused-to-metal fixed partial dentures (FPDs); 30 subjects received cemented porcelain-fused-to-metal FPDs; 14 subjects received implant-supported barretained overdentures; and three subjects received implant-retained telescopic crowns (Fig 4). The criteria used to measure success at the prosthetic level were the occurrence of technical complications, prosthetic maintenance, adequate function, and esthetics. The criteria reported to assess patient satisfaction level were discomfort, satisfaction with appearance, and ability to function and chew. These
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were recorded in the OHIP-14 questionnaire. Prosthetic complications were not common in this study. The main prosthetic complications were bar fracture, overdenture base fracture, abutment screw fracture, worn or fractured acrylic resin teeth, porcelain chipping, and retention clip fracture (Table 6). The average observation period after prosthesis delivery was 12.8 years (range, 3.4 to 22.3 years). Of all subjects, 9 (12.1%) had an observation period of more than 20 years (range, 20 to 22 years), 54 subjects (73%) had an observation period between 10 and 20 years, and 35 subjects (36.8%) had an observation period between 2.4 and 9.8 years. A significant Poisson regression model was generated (omnibus test df = 7; P < .001), showing that the number of factors for implant failure could be predicted with information about the patients’ sex, age, the timing of the bone graft to be performed, and whether radiotherapy was applied. The regression coefficients revealed that, on average, three items contributed significantly to implant failure. Nonetheless, the highest failures were expected for men (odds ratio [OR] = 2.948; 95% confidence interval [CI], 1.10 to 7.85; P = .031), patients receiving primary fibula free flap reconstruction, (OR = 3.696; 95% CI, 1.16 to 11.73; P = .027), and patients receiving radiotherapy (OR = 5.269; 95% CI, 1.40 to 19.7; P = .014) (Table 7).
DISCUSSION This retrospective study reviewed the long-term prognosis of implant-borne prostheses for the reconstruction of mandibular osseous defects. Reconstruction of the mandible following oral and maxillofacial neoplasm resection, trauma, and deformity remains a great challenge due to the alteration of intraoral soft and hard tissues. In rare circumstances, these defects can lead to abnormal social behavior. Since being introduced by Hidalgo in 1989, the vascularized fibula free flap has been accepted as a long-standing modality and the first choice for mandible continuity restoration.19 The dental implant–borne prosthesis became the first choice for oral functional rehabilitation. Many authors further proved that endosseous implants placed in composite-free grafts achieved acceptable esthetic and functional outcomes.9,20,21 Studies have shown that the 5-year success rates of implants placed in grafted bone without radiation therapy ranged from 91% to 98.6%, which were similar to the success rates of implants placed in natural bone.6,22,23 Delayed reconstruction of mandibular defects was preferred in this study because of the belief that primary reconstruction could potentially conceal tumor recurrence. In addition, the success rates of primary
Table 6 Prosthetic Complications During Follow-up Period Number of complications Complications
FPD group
RPD group
Bar fracture
NA
4
Overdenture base fracture
NA
1
Abutment screw fracture
3
4
Worn or fractured acrylic resin teeth
1
0
Porcelain chipping
4
1
Retention clip fracture
NA
2
FPD = fixed partial denture; NA = not applicable; RPD = removable partial denture.
fibula free flap reconstruction were not always satisfactory. While the merits of the fibula reconstruction technique have been well explained, few clinicians have addressed the prosthetic considerations. The vertical dimension between the occlusal plane and the reconstructed mandible can be overwhelmingly large (Fig 5). Longer implants have been used, but their use was not always possible because of the limited fibula height and thickness of the diaphysis. Selecting longer implant abutments also compensated for the discrepancy. However, a disproportionate implant-abutment ratio can result in various complications, such as unbalanced loading force, micromovement, repeated periimplantitis, marginal bone loss, and implant failure. “Double-barrel” fibula grafting and vertical distraction osteogenesis were introduced to mitigate these issues. In the double-barrel technique, the two fragments of fibula were positioned parallel to each other, which could double the bone height up to 3 cm. The mandible height was restored, and implants could be placed in quantitatively sufficient bone. However, there is a risk when using this technique of blocking the blood supply to the graft, which consequently causes flap failure. Distraction osteogenesis can be another approach to achieve bone augmentation of a fibula flap. In this technique, the soft tissue around the graft can be elongated and adapted without the risk of graft exposure.24 However, when preparing the osteotomy bed, the horizontal osteotomy must be widened as much as possible. If the remaining bone becomes too shallow, the risk of mandibular fracture and nerve damage will also increase. In this study, all implants were inserted 8 to 17 months after bony reconstruction. There have been some reports advocating primary insertion of dental implants combined with osseous reconstruction.25,26 Primary reconstruction with implants has some benefits; treatment time and cost are reduced, as some The International Journal of Oral & Maxillofacial Implants 175
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Fang et al
Table 7 Poisson Regression Analysis of the Implant Failures (74 Patients)* 95% Wald-type CI Upper limit
Wald chisquare
95% CI Lower limit
Upper limit
Parameter
B
(Intercept)
–4.242
0.6953
–5.605
–2.879
37.215
1
.000
0.014
0.004
0.056
1.483
0.8005
–0.086
3.052
3.431
1
.064
4.405
0.917
21.150
31 < Age < 60
0.090
0.7527
–1.385
1.566
0.014
1
.905
1.094
0.250
4.785
Age > 61
0
–
–
–
–
–
0.101
2.061
4.672
1
.031
–
–
–
–
–
0.152
2.462
1
.027
30 < Age
Male
1.081
Female
0
Primary bone graft
1.307
Delayed bone graft
0
Trauma
0.756
Benign tumor Malignancy Irradiated
–26.923 0 –1.662
Nonirradiated
0
(Scale)
1
SE
Hypothesis test
Lower limit
– 0.5002 – 0.5893 – 0.6164 – – 0.6729 –
–
–
–0.452
1.964
–
–
–
–
–2.981
–0.343
–
–
4.920 – 1.505 – – 6.100 –
df
P
Odds ratio
1 2.948 1 3.696
1.106
– 7.857
–
–
1.164
11.731
–
–
1
.220
2.130
0.636
7.131
–
–
2.029E-12
0.000
0.000
–
–
1
.014
–
–
1
–
1 5.269 1
–
–
–
–
1.409
19.710
–
–
CI = confidence interval. *Dependent variable: implants lost per patient; model: (intercept), age, sex, bone graft, etiology, radiotherapy; offset = total implants placed per patient.
Fig 5 Intraoral view of the customized milled titanium bar. The overwhelming discrepancy between the occlusal plane and the implant shoulder indicated the unbalanced implant-abutment ratio, which was a risk factor for long-term success.
patients are not willing to receive additional implant surgeries. However, the procedure is still controversial, because primary implant insertions could result in unexpected and unfavorable occlusal relationships between the reconstructed mandible and the maxilla. The periosteal blood supply is disturbed, which compromises the bone graft consolidation and mucosa healing.27 Furthermore, in cancer-resected patients, there is the risk of tumor recurrence, which requires sufficient postoperative observation. Within the authors’ limited experience, careful treatment time selection and weighing of the disadvantages against
the benefits of primary implant insertion is of great importance. Following consideration of the long-term prosthetic results, a minimal interval of 6 months between mandible reconstruction and implant insertion is preferred in the authors’ department. Computer-guided graft and implant placement have gained a great deal of popularity during the last decade. With CT-guided surgery, the implants are placed exactly where virtually planned. There is little room for error when a computer-guided surgical template is seated precisely with anchor pins. However, there are concerns that have been raised by many authors regarding fibula free flap surgery. Most cancer patients require combined bone and soft tissue grafting. Currently, only bony defects can be assessed precisely, but prediction of soft tissue alteration cannot reflect the precise intraoperative and postoperative changes, such as inflammation and edema. Therefore, combined hard and soft tissue defects must always be considered and treated by overcorrection under visual feedback. Shallow vestibules and bulky flaps are common in reconstructed oral cancer and trauma patients. The thick subcutaneous tissue impedes dental prosthesis retention and is regarded as a potential risk factor for peri-implant mucositis. Recurrent soft tissue irritations can lead to unpredictable implant prognosis (Fig 6). A prerequisite for maintaining the function of dental implants is the presence of adequate keratinized soft tissue to serve as a barrier at the implant-gingiva junction. Furthermore, resection of osseous structures is often combined with resection of keratinized tissue, leaving the remnant keratinized soft tissue insufficient.
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Debulking of flaps, using palatal grafts or STSGs, has been proposed with various merits and drawbacks. Palatal grafts, which are routinely used for soft tissue grafting in esthetic regions, might not fit the dimensions of defects in cancer or trauma patients. STSGs, due to the varied selection of donor sites and flexible thickness, are preferred. The previously reported twostage submerged STSG technique has become a routine technique for keratinized soft tissue deficiencies in the authors’ department. In this two-stage technique, the STSG is placed beneath the bulky flap in the stageone surgery. The hypothesis of the technique was that the risk of STSG infection could be reduced by isolating the skin graft and the oral cavity. In addition, nutrition needed by the graft could be supplied by the underlying periosteum and the surrounding tissue fluids. However, there were controversies, as these substitutes differed from mucosa around natural teeth. Oral mucosa had fewer wrinkles, no appendages, more moisture, and deeper pigmentation.20 These characteristics can lead to changes in peri-implant conditions and might explain why implants in reconstructed mandibles were more susceptible to peri-implant inflammation. Prosthetic restoration in this study can be classified into two types: fixed and removable. Fixed prostheses feel much more effortless and comfortable compared with removable ones. From a biomechanical perspective, fixed prostheses apply constant and balanced occlusal stimulus to the residual bone, a process similar to that of natural dentition maintaining the marginal level of the alveolar bone. However, hygiene access to the circumferential tissue around the fixed prosthesis or crown is limited, and soft tissue irritations are prone to occur if scheduled maintenance is compromised. Fixed prostheses also require more implants, adding to the cost of the treatment plan. Removable prostheses can compensate for local soft tissue defects and lead to better esthetic outcomes. Additionally, implant stability and abutment screw loosening can be assessed during follow-up visits. Both types of restoration have their benefits and shortcomings and should be selected on a case-by-case basis. In some cancer patients, radiotherapy was inevitable. However, radiotherapy has been considered a contraindication to implant surgery because the capacity for osteogenesis is decreased, and osseointegration is impaired. Some studies showed that radiation doses exceeding 50 Gy could induce negative effects, including capillary thrombosis, osteoblast damage, and reduced vascularity.28,29 Nine patients in this study underwent adjuvant radiotherapy prior to implant placement. The implant survival rate during follow-up was lower than that of implants placed in nonirradiated bone. These figures were consistent with literature findings. It was believed that the implant survival rate
Fig 6 The “doughnut” lesion in peri-implant tissues.
in the cancer patient category was acceptable, considering the unfavorable environment for conventional removable prosthetic rehabilitation and the significant improvement in quality of life after treatment.
CONCLUSION This retrospective study showed that the functionality of implant-borne rehabilitation of fibula free flap– reconstructed patients was stable and predictable. Prosthetic-oriented and patient-specific treatment planning before surgery is of great importance. Regular follow-up visits and oral hygiene maintenance also contributed to the treatment successes.
ACKNOWLEDGMENTS The authors reported no conflicts of interest related to this study.
REFERENCES 1. Marx RE. Reconstruction of defects caused by bisphosphonateinduced osteonecrosis of the jaws. J Oral Maxillofac Surg 2009;67: 107–119. 2. Disa JJ, Cordeiro PG. Mandible reconstruction with microvascular surgery. Semin Surg Oncol 2000;19:226–234. 3. Gonzalez-Garcia R, Naval-Gias L, Rodriguez-Campo FJ, MunozGuerra MF, Sastre-Perez J. Vascularized free fibular flap for the reconstruction of mandibular defects: Clinical experience in 42 cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:191–202. 4. Schrag C, Chang YM, Tsai CY, Wei FC. Complete rehabilitation of the mandible following segmental resection. J Surg Oncol 2006; 94:538–545. 5. Triana RJ Jr, Uglesic V, Virag M, et al. Microvascular free flap reconstructive options in patients with partial and total maxillectomy defects. Arch Facial Plast Surg 2000;2:91–101. 6. Chiapasco M, Abati S, Ramundo G, Rossi A, Romeo E, Vogel G. Behavior of implants in bone grafts or free flaps after tumor resection. Clin Oral Implants Res 2000;11:66–75.
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Fang et al
7. Paranque AR, Steve M, Vazquez L, Bolleyn A, Roze-Pellat MA, Dohan Ehrenfest DM. Esthetic and functional reconstruction of the posttumoral interrupted mandible with double-barrel fibular free flap graft: Rationale for a microsurgical and prosthodontic approach. J Oral Implantol 2011;37:571–577. 8. Frodel JL Jr, Funk GF, Capper DT, et al. Osseointegrated implants: A comparative study of bone thickness in four vascularized bone flaps. Plast Reconstr Surg 1993;92:449–455. 9. Gbara A, Darwich K, Li L, Schmelzle R, Blake F. Long-term results of jaw reconstruction with microsurgical fibula grafts and dental implants. J Oral Maxillofac Surg 2007;65:1005–1009. 10. Ferrari S, Copelli C, Bianchi B, et al. Rehabilitation with endosseous implants in fibula free-flap mandibular reconstruction: A case series of up to 10 years. J Craniomaxillofac Surg 2013;41:172–178. 11. Hoffman GR, Islam S, Eisenberg RL. Microvascular reconstruction of the mouth, face and jaws. Oromandibular reconstruction—free fibula flap. Aust Dent J 2012;57:379–387. 12. Al Mardini M. Prosthetic rehabilitation of the head and neck: The state of the art. Curr Opin Otolaryngol Head Neck Surg 2009;17: 253–257. 13. Smolka K, Kraehenbuehl M, Eggensperger N, et al. Fibula free flap reconstruction of the mandible in cancer patients: Evaluation of a combined surgical and prosthodontic treatment concept. Oral Oncol 2008;44:571–581. 14. Shpitzer T, Neligan PC, Gullane PJ, et al. Oromandibular reconstruction with the fibular free flap. Analysis of 50 consecutive flaps. Arch Otolaryngol Head Neck Surg 1997;123:939–944. 15. Fang W, Ma W, Ma WG, Li DH, Liu BL. A new submerged split-thickness skin graft technique to rebuild peri-implant keratinized soft tissue in composite flap reconstructed mandible or maxilla. Oral Surg Oral Med Oral Pathol Oral Radiol 2012;113:e4–e9. 16. Albrektsson T, Zarb G, Worthington P, Eriksson AR. The long-term efficacy of currently used dental implants: A review and proposed criteria of success. Int J Oral Maxillofac Implants 1986;1:11–25. 17. Montero J, Castillo-Oyague R, Lynch CD, Albaladejo A, Castano A. Self-perceived changes in oral health-related quality of life after receiving different types of conventional prosthetic treatments: A cohort follow-up study. J Dent 2013;41:493–503. 18. Brennan DS, Spencer AJ. Dimensions of oral health related quality of life measured by EQ-5D+ and OHIP-14. Health Qual Life Outcomes 2004;2:35.
19. Hidalgo DA. Fibula free flap: A new method of mandible reconstruction. Plast Reconstr Surg 1989;84:71–79. 20. Kramer FJ, Dempf R, Bremer B. Efficacy of dental implants placed into fibula-free flaps for orofacial reconstruction. Clin Oral Implants Res 2005;16:80–88. 21. Nelson K, Heberer S, Glatzer C. Survival analysis and clinical evaluation of implant-retained prostheses in oral cancer resection patients over a mean follow-up period of 10 years. J Prosthet Dent 2007;98:405–410. 22. Riediger D. Restoration of masticatory function by microsurgically revascularized iliac crest bone grafts using enosseous implants. Plast Reconstr Surg 1988;81:861–877. 23. Kovacs AF. The fate of osseointegrated implants in patients following oral cancer surgery and mandibular reconstruction. Head Neck 2000;22:111–119. 24. Ortakoglu K, Suer BT, Ozyigit A, Ozen T, Sencimen M. Vertical distraction osteogenesis of fibula transplant for mandibular reconstruction: A case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;102:e8–e11. 25. Chang YM, Wallace CG, Tsai CY, Shen YF, Hsu YM, Wei FC. Dental implant outcome after primary implantation into double-barreled fibula osteoseptocutaneous free flap-reconstructed mandible. Plast Reconstr Surg 2011;128:1220–1228. 26. Schoen PJ, Raghoebar GM, Bouma J, et al. Prosthodontic rehabilitation of oral function in head-neck cancer patients with dental implants placed simultaneously during ablative tumour surgery: An assessment of treatment outcomes and quality of life. Int J Oral Maxillofac Surg 2008;37:8–16. 27. Korfage A, Schoen PJ, Raghoebar GM, Roodenburg JL, Vissink A, Reintsema H. Benefits of dental implants installed during ablative tumour surgery in oral cancer patients: A prospective 5-year clinical trial. Clin Oral Implants Res 2010;21:971–979. 28. Granstrom G. Radiotherapy, osseointegration and hyperbaric oxygen therapy. Periodontol 2000 2003;33:145–162. 29. Schon R, Ohno K, Kudo M, Michi K. Peri-implant tissue reaction in bone irradiated the fifth day after implantation in rabbits: Histologic and histomorphometric measurements. Int J Oral Maxillofac Implants 1996;11:228–238.
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1Resident,
State Key Laboratory of Military Stomatology, Departments of Implant Dentistry and Oral and Maxillofacial Surgery, School of Stomatology, The Fourth Military Medical University, Xi’an, China. 2Professor, State Key Laboratory of Military Stomatology, Department of Oral and Maxillofacial Surgery, School of Stomatology, The Fourth Military Medical University, Xi’an, China. 3 Professor, State Key Laboratory of Military Stomatology, Department of Oral and Maxillofacial Surgery, School of Stomatology, The Fourth Military Medical University, Xi’an, China. 4Professor, State Key Laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an, China. Wei Fang and Yan-pu Liu contributed equally to this work. Correspondence to: Professor Yimin Zhao, School of Stomatology, Fourth Military Medical University, 145 W Changle Rd, Xian, 710032, China. Fax: +86-29-847-76231. Email: [email protected] ©2015 by Quintessence Publishing Co Inc.
E
xtensive neoplasm resections and trauma in the head and neck region often result in facial bone disfiguration and soft tissue deformities.1 Problems arising from these defects include unesthetic facial contours and compromised oral functions, such as speech, mastication, and swallowing. Advances in microsurgical techniques have brought about significant improvements in oral functional rehabilitation. Vascularized composite autogenous bone grafts offer great potential to restore bone continuity and soft tissue integrity.2–4 The bone flaps can be transplanted with a muscle and skin paddle, which allows the simultaneous reconstruction of both hard and soft tissue with esthetic and functional outcomes that are acceptable to clinicians and patients. A large number of composite bone flaps have been introduced, such as radius, scapula, thoracic rib, iliac crest, and fibula.5,6 Of note, the fibula free flap has demonstrated high reliability and versatility for restoring segmental mandibular defects. The length of harvested fibula free flaps is up The International Journal of Oral & Maxillofacial Implants 169
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Treatment Planning
Fig 1 Virtual implant insertion and tooth arrangement using CAD software.
to 25 to 27 cm, providing a long pedicle to be osteotomized for mandibular defects of almost any length and is especially suitable for defects of more than 6 cm. Fibula free flaps can be used as osteomyocutaneous or osteomuscular flaps. The medullar and periosteal vascularization allows the bone graft to be shaped to an ideal morphologic fit to restore the continuity of the mandible.7 Frodel et al reported that a fibula free flap was capable of accommodating 10-mm implants, taking advantage of bicortical implant-bone anchorage.8 Some authors have reported long-term results of implants placed into a fibula free flap, notably Gbara et al in a 20-year follow-up study and Ferrari et al in a mean 10-year follow-up study.9,10 Despite advances in microsurgical reconstruction approaches, implant-borne rehabilitation on reconstructed mandibles is still a challenge. Adverse conditions include shallow vestibule, few or no residual teeth, bulky and mobile flap, considerable vertical height, and fragile oral mucosa.11,12 The purpose of this study is to review the authors’ experience with fibula free flaps and dental implant-borne rehabilitation for mandibular reconstruction over the past 20 years.
MATERIALS AND METHODS Patient Data
Between 1988 and 2010, patients underwent mandibular reconstruction with fibula free flaps followed by dental implant–borne rehabilitation in the Department of Oral and Maxillofacial Surgery and the Department of Implant Dentistry, Third Affiliated Hospital, Fourth Military Medical University, Xi’an and were enrolled in this retrospective study. Ethical approval was obtained from the Ethics Committee of the university.
Dental rehabilitation of mandibular defects requires comprehensive and multidisciplinary planning prior to surgery. In the present study, treatment planning was performed with the collaboration of maxillofacial surgeons, implant dentists, physicians, and experts in other specialties. On the patient’s initial visit, the intraoral status was examined and recorded, including current defects, prostheses, occlusal relationships, soft tissue irritation, tongue mobility, and residual dentition. Because mandibular defects often result in unesthetic and asymmetric contours, postoperative deviation of the mandible was taken into consideration. After the intraoral examination, radiographic evaluations were performed, including panoramic radiographs and spiral computed tomography (CT). A study cast was mounted in a mean value articulator, followed by a diagnostic wax-up. In some cases, a provisional denture incorporating radiopaque material (gutta percha) was fabricated to mark the corresponding implant sites. Surgical and prosthetic plans were analyzed on the study casts and by means of measurements on the panoramic radiographs. Computer-aided design (CAD) software (Mimics 10.01, SimPlant Pro 11.03, Materialise Software NV) facilitated virtual bone graft and implant insertions (Fig 1).
Primary Defects and Fibula Free Flap Reconstruction Surgery
Positions of mandibular defect sites were classified as lateral, anterior, anterolateral, and lateroanterolateral. The osseous defects were classified by Smolka as Class I to III according to the extent and number of osteotomies needed for the fibula. Class I defects had no osteotomy, Class II had one osteotomy, and Class III had two or more osteotomies. The extent of soft tissue defects was categorized into groups A to D as proposed by Shpitzer et al and modified by Smolka et al.13,14 For the operation, the patient was under general anesthesia in dorsal recumbency. The fibula free flap was usually harvested using a two-team approach in which the flap dissection and preparation of the recipient bed were performed simultaneously. The bony stumps of the primary defects were fully exposed to the buccal and lingual sides. Bone blocks were shaped according to the defect morphology before being affixed to the residual bone with titanium reconstruction plates. The vascularized graft was anastomosed to the facial or superior thyroid arteries and veins.
Dental Implant Insertion
Dental implants were placed after fibula free flap reconstruction. Prophylactic antibiotics were given 30 minutes prior to surgery and for 3 days postoperatively, usually 500 mg of ornidazole. The stage-one
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implant surgeries were performed by experienced surgeons, following the instructions of the implant manufacturer. Patients were required to visit the clinic the day after surgery to assess the wound. Stitches were removed 10 days postoperatively.
Keratinized Soft Tissue Grafting and Vestibuloplasty
Sufficient keratinized soft tissue around the dental implant plays an essential role in the long-term success of implant-borne prostheses. In mandible-reconstructed patients, loss of keratinized tissue and vestibular depth can compromise the dental rehabilitation and oral hygiene access. Keratinized soft tissue grafting with vestibuloplasty was performed accordingly. The submerged grafting technique was utilized as previously reported.15 In this technique, the buccal and lingual sides of the flap were elevated supraperiosteally. The 0.02-inch-thick split-thickness skin graft (STSG) was harvested with the required dimensions. After inserting the implant, the STSG was placed supraperiosteally with its margins sutured to the periosteum (Fig 2); then, the flap was closed with interrupted sutures. After a 1-month healing period, vestibuloplasty was performed. Reentry to the STSG was achieved by elevating the buccal and lingual flaps. The buccal and lingual flaps were trimmed and secured with tight sutures to the underlying periosteum at a more apical level to obtain an ideal vestibule position. Iodoform gauze was pressed against the newly formed vestibule for 2 weeks to stabilize its position. After 2 weeks, an impression was taken using hydrophilic polyvinyl siloxane (DMG Dental-Material) with an open or closed custom-tray impression technique. The final prostheses were delivered 10 days thereafter.
Postoperative Follow-up
Once implant-borne prostheses were placed, instructions for hygiene maintenance were given to the patients as follows: (1) Cotton buds moistened in 50:50 hydrogen peroxide:saline were to be used to remove debris from around the transmucosal abutment cylinders; (2) an interproximal toothbrush with soft bristles was to be used to clean superior aspects of the transmucosal abutment cylinders. The follow-up protocol was established with standardized evaluations, including radiographic data, clinical examination, and patient review. The success of implant osseointegration was assessed according to the standard proposed by Albrektsson: an absence of persistent pain, mobility, or radiolucency around the implant, and bone resorption of no more than 1.5 mm in the first year of prosthetic loading and 0.2 mm in subsequent years.16 The patients were examined radiographically and clinically at the following
Fig 2 The STSG was perforated and then secured with titanium screws. The margin of the STSG was sutured at the vestibule position on the buccal and lingual sides.
time points: 1 day after implant placement (stage-one surgery), immediately after screw uncovering (stagetwo surgery) and prosthesis delivery, at the 6-month recall after treatment, and at annual visits thereafter. The mesial and distal bone absorption was measured on the panoramic radiograph from the implant shoulder to the coronal bone-to-implant contact (BIC) surface. The initial measurement was performed 1 day after implant placement and served as the baseline for future comparisons. Pocket depth (PD) and bleeding on probing (BOP) were also examined and recorded at four sites on the implant (mesiobuccal, mesiolingual, distobuccal, and distolingual). A questionnaire was administered to patients 1 year postoperatively to review their experience with the dental rehabilitation using the Oral Health Impact Profile–14 (OHIP-14) form, which uses 14 items to evaluate seven categories of oral function and subjective perceptions, including physical pain, psychologic discomfort, physical disability, psychologic disability, social disability, and handicap. For every question on the OHIP-14 form, subjects were asked how frequently they had experienced impact regarding that particular item in the preceding 12 months using a 5-point scale coded 4 = very often, 3 = fairly often, 2 = occasionally, 1 = hardly ever, and 0 = never.17,18
Statistical Analysis
Implant survival was analyzed using Kaplan-Meier estimates. The survival curves of irradiated and nonirradiated subjects were compared using a log-rank test. A Poisson regression model was calculated to predict items that significantly contributed to the loss of implants. The Poisson regression analysis took into consideration the presence of multiple implants in the same individual. Implant loss per patient was taken as The International Journal of Oral & Maxillofacial Implants 171
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Fang et al
Table 1 Patient General Information Characteristics Age (y)
No. of patients
Table 2 Tumor Location and Staging for Cancer Patients %
< 30 30–65 > 65
10 48 16
13.5 64.9 21.6
Female Male
13 61
17.6 82.4
Defect cause Oral malignancies Oral benign tumors Trauma Osteoradionecrosis
47 4 18 5
63.5 5.5 24.3 6.7
Radiotherapy Yes No
9 65
12.2 87.8
Sex
the dependent variable, and the Poisson’s regression with a logarithmic link-function and total implants placed per patient was taken as an offset variable. The statistical significance (α = .05) of the results was determined. Statistical analyses were performed with SPSS software, version 16.0 for Windows (SPSS).
RESULTS One hundred twenty-six patients underwent reconstruction of the mandible with a fibula free graft followed by the insertion of endosseous dental implants. Of the subjects who completed the dental rehabilitation, 74 patients were enrolled in this retrospective study (61 men and 13 women; age range, 19 to 75 years; mean, 47 years). Nine patients received radiotherapy in the head and neck region (dose range, 40 to 55 Gy). The radiotherapy was begun 3 to 4 weeks after primary tumor resection. Patient characteristics are presented in Tables 1 and 2.
Primary Defects and Fibula Free Flap Reconstruction Surgery
All defects in this study were Class II (63 cases) or Class III (11 cases). The extent of soft tissue defects is shown in Table 3. The length of the mandibular defects in this study varied from 7 to 12 cm. Both primary and secondary bony reconstruction techniques were utilized. In 12 patients, fibula free flap reconstruction was performed with ablation of the affected bone segments at the same time (primary reconstruction). Sixth-two patients underwent secondary lesion ablation. The defects were maintained by titanium reconstruction plates. Delayed fibula free flap reconstruction (secondary reconstruction) was performed 6 to 26 months postoperatively, depending on the dimensions of the defect and whether the recipient had been irradiated. The average transplanted fibula length was 11.6 cm (range, 9 to 15 cm), with skin paddle dimension of
Patient age (y)
Sex
Primary tumor
Stage
Total dose (Gy)
79
Female
Base of tongue
T3N1
51
58
Male
Mandibular gingiva
T1N0
NA 43
66
Male
Floor of mouth
T2N0
48
Male
Tongue
T3N2
55
50
Female
Mandibular gingiva
T1N0
NA
46
Male
Mandibular gingiva
T2N0
NA
42
Male
Tongue/floor of mouth
T1N0
NA
55
Female
Mandibular gingiva
T1N0
NA
67
Male
Tongue
T1N0
NA
58
Male
Tongue
T2N0
40
51
Male
Mandibular gingiva
T2N1
NA
62
Male
Mandibular gingiva
T4N1
46
59
Female
Mandibular gingiva
T1N0
NA
64
Male
Oropharynx
T2N0
NA
47
Male
Mandibular gingiva
T1N0
NA
61
Male
Mandibular gingiva
T2N0
49
53
Male
Mandibular gingiva
T1N0
NA
54
Male
Mandibular gingiva
T2N0
NA
41
Male
Tongue
T1N0
NA
62
Male
Mandibular gingiva
T3N1
47
49
Female
Tongue
T1N0
NA
44
Male
Tongue
T1N0
NA
47
Female
Mandibular gingiva
T2N0
NA
63
Male
Mandibular gingiva
T1N0
NA
50
Male
Oropharynx
T1N0
NA
55
Male
Mandibular gingiva
T1N0
NA
58
Male
Mandibular gingiva
T3N2
53
47
Male
Tongue
T1N0
NA
41
Male
Floor of mouth/tongue
T2N0
NA
39
Male
Mandibular gingiva
T1N0
NA
54
Male
Mandibular gingiva
T1N0
NA
59
Male
Mandibular gingiva
T1N0
NA
58
Male
Floor of mouth
T2N0
NA
69
Female
Mandibular gingiva
T1N0
NA
72
Male
Mandibular gingiva
T1N0
NA
75
Male
Tongue
T1N0
NA
56
Female
Mandibular gingiva
T1N0
NA
52
Male
Floor of mouth
T2N0
NA
68
Male
Mandibular gingiva
T1N0
NA
61
Male
Mandibular gingiva
T1N0
NA
74
Male
Floor of mouth
T1N0
NA
53
Male
Mandibular gingiva
T1N0
NA
46
Male
Mandibular gingiva
T1N0
NA
55
Male
Tongue
T3N2
42
52
Male
Tongue
T1N0
NA
46
Male
Floor of mouth
T1N0
NA
48
Male
Mandibular gingiva
T2N0
NA
NA = not applicable.
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Fang et al
Table 3 Soft Tissue Deficiency Classification* Defect extension
No. of patients
0.8
A
Lateral mandibular gingiva and mouth floor
51
B
Lateral mandibular gingiva, mouth floor, and part of tongue
13
C
Anterior mandibular gingiva and mouth floor
6
D
Oropharyngeal soft tissue including parts of the tonsil and parts of the base tongue
4
*As proposed by Spitzer et al,14 1997 and modified by Smolka et al,13 2008.
Follow-up (y)
No. of patients
Mean
SD
Bone resorption Mean
Treatment No radiotherapy Radiotherapy No radiotherapycensored Radiotherapycensored
0.6 0.4 0.2 0.0
Table 4 Peri-Implant Pocket Depths and Bone Resorption at Follow-up Pocket depth
Cumulative survival
Group
1.0
SD
1
74
3.17
1.21
0.88
0.51
5
54
3.41
1.05
1.20
0.49
10
32
3.29
0.98
1.48
0.56
15
24
3.32
0.70
1.76
0.50
20
9
3.58
0.54
1.94
0.20
5.7 × 2.9 cm (range, 2.5 × 3 cm to 17 × 5 cm). The vascularized graft was anastomosed to the facial arteries and veins. In three patients, the facial arteries were too fragile for vascular anastomosis. The fibular artery was anastomosed with the superior thyroid artery. In 65 patients, the fibula free flap was uneventful postoperatively. Impaired ankle function in the donor site was observed in three patients. One patient presented with ankle stiffness, and two patients were diagnosed with ankle instability based on the Ankle-Hindfoot Scale and radiographic manifestations. The ankle function of two patients was considerably improved within 6 months postoperatively. One patient continued to present ankle instability during follow-up. Six patients developed complications in the fibula free flap recipient site. Two patients presented full or partial flap failures; wound infections were observed in four patients. One subject presented wound dehiscence 1 day postoperatively. In the revision surgery, the grafted fibula was perforated with a round bur to induce the blood supply. The wound healed eventually after 10 days.
Implant Survival and Oral Function Evaluation
Dental implants were placed 8 to 17 months (mean, 13.5 months) after fibula free flap reconstruction. The implants were placed in a two-stage surgery protocol. All implants were inserted using the submerged
0.0
5.0
10.0
15.0
20.0
25.0
Years to the first implant failure Fig 3 Kaplan-Meier survival analysis for implants placed in reconstructed mandibles. The diagram shows the survival of all implants placed in irradiated and nonirradiated patients during the observation period.
technique. The following implant systems were used: Brånemark (Nobel Biocare), Straumann SLA (Straumann), and MDIC (MDIC Medical). Seventy-four patients received 192 implants (57 Brånemark, 92 MDIC, 43 Straumann SLA). The average implant length was 11.5 mm (range, 8 to 13 mm). The average number of implants placed per patient was five (range, two to nine). The average time between the implant placement (stage-one surgery) and screw uncovering (stage-two surgery) was 7.5 months (range, 5 to 11.4 months). A total of 18 implants had failed at the time of the investigation: 12 implants were lost before prosthetic loading (6.2%); 6 implants were lost during follow-up observation (3.1%). Thirteen failed implants were replaced and successfully reosseointegrated. Additionally, 5 implants (2.6%) osseointegrated successfully but were rendered useless owing to unfavorable positioning for prosthetic retention. Sleeping implants were allowed to remain in situ. The overall implant survival rates in patients were 90.1%, 83.1%, and 69.3% after 5, 10, and 20 years, respectively (Fig 3). The Kaplan-Meier curve presented the effect of radiotherapy on implant osseointegration. For irradiated patients, the implant survival rates were 87.5%, 75%, and 50%, respectively. In the nonirradiated patients, there was sufficient evidence from the Kaplan-Meier survival curves of a difference in the time to first implant failure (log-rank test, 4.35; P = .03). Alterations of the crestal bone levels and pocket depths of dental implants are shown in Table 4. These values corresponded to the radiographic findings. The distribution of responses to the OHIP-14 items is presented in Table 5, which shows that most of the subjects rarely reported having had problems 1 year postoperatively The International Journal of Oral & Maxillofacial Implants 173
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Fang et al
Table 5 Distribution of OHIP-14 Items 1 Year After Dental Rehabilitation Distribution of responses (%)* Impact item
0
1
2
3
4
Mean
SE
OH1
How often in the last year have you had problems with your teeth, mouth, or dentures?
19.6
23.9
26.1
21.7
8.7
1.76
0.184
OH2
Have you had trouble pronouncing any words because of problems with your teeth, mouth, or dentures?
31.8
22.7
20.5
15.9
9.1
1.48
0.202
OH3
Have you had painful aching in your mouth?
44.2
20.9
16.3
7.0
11.6
1.21
0.212
OH4
Have you found it uncomfortable to eat any foods because of problems with your teeth, mouth, or dentures?
28.9
33.3
20.0
11.1
6.7
1.33
0.180
OH5
Have you felt self-conscious because of problems with your teeth, mouth, or dentures?
31.8
27.3
22.7
13.6
4.5
1.32
0.181
OH6
Have you felt tense because of problems with your teeth, mouth, or dentures?
26.1
50.0
15.2
2.2
6.5
1.13
0.154
OH7
Has your diet been unsatisfactory because of problems with your teeth, mouth, or dentures?
25.6
32.6
20.9
9.3
11.6
1.49
0.198
OH8
Have you had to interrupt meals because of problems with your teeth, mouth, or dentures?
45.7
30.4
10.9
6.5
6.5
0.98
0.177
OH9
Have you found it difficult to relax because of problems with your teeth, mouth, or dentures?
26.2
35.7
19.0
16.7
2.4
1.33
0.173
OH10
Have you been a bit embarrassed because of problems with your teeth, mouth, or dentures?
25.0
40.9
18.2
11.4
4.5
1.30
0.168
OH11
Have you been a bit irritable with other people because of problems with your teeth, mouth, or dentures?
9.3
34.9
30.2
16.3
9.3
1.81
0.171
OH12
Have you had difficulty doing your usual jobs because of problems with your teeth, mouth, or dentures?
15.6
40.0
26.7
4.4
13.3
1.60
0.181
OH13
Have you felt that life in general was less satisfying because of problems with your teeth, mouth, or dentures?
10.9
32.6
28.3
15.2
13.0
1.87
0.177
OH14
Have you been totally unable to function because of problems with your teeth, mouth, or dentures?
13.6
38.6
27.3
9.1
11.4
1.66
0.178
*0 = never; 1 = hardly ever; 2 = occasionally; 3 = very often; 4 = fairly often.
vestibuloplasty. There were two types of keratinized soft tissue donor sites: palatal grafts and STSGs. In this study, a palatal graft was used for four patients. An STSG, which provided larger tissue dimensions, was used for 22 patients. Soft tissue grafting and vestibuloplasty were performed in the second-stage implant surgery. In eight patients who underwent the STSG procedure, the submerged grafting technique was utilized.
Prosthetic Rehabilitation and Complications
Fig 4 Intraoral view of telescopic abutments. Note the smooth and immobile soft tissue around the implants after skin grafting and vestibuloplasty procedures.
on all items. There were generally low percentages of patients reporting that they had problems very often in the first year of follow-up.
Keratinized Soft Tissue Grafting
In this retrospective investigation, 26 patients (35.1%) underwent keratinized soft tissue grafting with
Twenty-seven subjects received screw-retained porcelain-fused-to-metal fixed partial dentures (FPDs); 30 subjects received cemented porcelain-fused-to-metal FPDs; 14 subjects received implant-supported barretained overdentures; and three subjects received implant-retained telescopic crowns (Fig 4). The criteria used to measure success at the prosthetic level were the occurrence of technical complications, prosthetic maintenance, adequate function, and esthetics. The criteria reported to assess patient satisfaction level were discomfort, satisfaction with appearance, and ability to function and chew. These
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Fang et al
were recorded in the OHIP-14 questionnaire. Prosthetic complications were not common in this study. The main prosthetic complications were bar fracture, overdenture base fracture, abutment screw fracture, worn or fractured acrylic resin teeth, porcelain chipping, and retention clip fracture (Table 6). The average observation period after prosthesis delivery was 12.8 years (range, 3.4 to 22.3 years). Of all subjects, 9 (12.1%) had an observation period of more than 20 years (range, 20 to 22 years), 54 subjects (73%) had an observation period between 10 and 20 years, and 35 subjects (36.8%) had an observation period between 2.4 and 9.8 years. A significant Poisson regression model was generated (omnibus test df = 7; P < .001), showing that the number of factors for implant failure could be predicted with information about the patients’ sex, age, the timing of the bone graft to be performed, and whether radiotherapy was applied. The regression coefficients revealed that, on average, three items contributed significantly to implant failure. Nonetheless, the highest failures were expected for men (odds ratio [OR] = 2.948; 95% confidence interval [CI], 1.10 to 7.85; P = .031), patients receiving primary fibula free flap reconstruction, (OR = 3.696; 95% CI, 1.16 to 11.73; P = .027), and patients receiving radiotherapy (OR = 5.269; 95% CI, 1.40 to 19.7; P = .014) (Table 7).
DISCUSSION This retrospective study reviewed the long-term prognosis of implant-borne prostheses for the reconstruction of mandibular osseous defects. Reconstruction of the mandible following oral and maxillofacial neoplasm resection, trauma, and deformity remains a great challenge due to the alteration of intraoral soft and hard tissues. In rare circumstances, these defects can lead to abnormal social behavior. Since being introduced by Hidalgo in 1989, the vascularized fibula free flap has been accepted as a long-standing modality and the first choice for mandible continuity restoration.19 The dental implant–borne prosthesis became the first choice for oral functional rehabilitation. Many authors further proved that endosseous implants placed in composite-free grafts achieved acceptable esthetic and functional outcomes.9,20,21 Studies have shown that the 5-year success rates of implants placed in grafted bone without radiation therapy ranged from 91% to 98.6%, which were similar to the success rates of implants placed in natural bone.6,22,23 Delayed reconstruction of mandibular defects was preferred in this study because of the belief that primary reconstruction could potentially conceal tumor recurrence. In addition, the success rates of primary
Table 6 Prosthetic Complications During Follow-up Period Number of complications Complications
FPD group
RPD group
Bar fracture
NA
4
Overdenture base fracture
NA
1
Abutment screw fracture
3
4
Worn or fractured acrylic resin teeth
1
0
Porcelain chipping
4
1
Retention clip fracture
NA
2
FPD = fixed partial denture; NA = not applicable; RPD = removable partial denture.
fibula free flap reconstruction were not always satisfactory. While the merits of the fibula reconstruction technique have been well explained, few clinicians have addressed the prosthetic considerations. The vertical dimension between the occlusal plane and the reconstructed mandible can be overwhelmingly large (Fig 5). Longer implants have been used, but their use was not always possible because of the limited fibula height and thickness of the diaphysis. Selecting longer implant abutments also compensated for the discrepancy. However, a disproportionate implant-abutment ratio can result in various complications, such as unbalanced loading force, micromovement, repeated periimplantitis, marginal bone loss, and implant failure. “Double-barrel” fibula grafting and vertical distraction osteogenesis were introduced to mitigate these issues. In the double-barrel technique, the two fragments of fibula were positioned parallel to each other, which could double the bone height up to 3 cm. The mandible height was restored, and implants could be placed in quantitatively sufficient bone. However, there is a risk when using this technique of blocking the blood supply to the graft, which consequently causes flap failure. Distraction osteogenesis can be another approach to achieve bone augmentation of a fibula flap. In this technique, the soft tissue around the graft can be elongated and adapted without the risk of graft exposure.24 However, when preparing the osteotomy bed, the horizontal osteotomy must be widened as much as possible. If the remaining bone becomes too shallow, the risk of mandibular fracture and nerve damage will also increase. In this study, all implants were inserted 8 to 17 months after bony reconstruction. There have been some reports advocating primary insertion of dental implants combined with osseous reconstruction.25,26 Primary reconstruction with implants has some benefits; treatment time and cost are reduced, as some The International Journal of Oral & Maxillofacial Implants 175
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Fang et al
Table 7 Poisson Regression Analysis of the Implant Failures (74 Patients)* 95% Wald-type CI Upper limit
Wald chisquare
95% CI Lower limit
Upper limit
Parameter
B
(Intercept)
–4.242
0.6953
–5.605
–2.879
37.215
1
.000
0.014
0.004
0.056
1.483
0.8005
–0.086
3.052
3.431
1
.064
4.405
0.917
21.150
31 < Age < 60
0.090
0.7527
–1.385
1.566
0.014
1
.905
1.094
0.250
4.785
Age > 61
0
–
–
–
–
–
0.101
2.061
4.672
1
.031
–
–
–
–
–
0.152
2.462
1
.027
30 < Age
Male
1.081
Female
0
Primary bone graft
1.307
Delayed bone graft
0
Trauma
0.756
Benign tumor Malignancy Irradiated
–26.923 0 –1.662
Nonirradiated
0
(Scale)
1
SE
Hypothesis test
Lower limit
– 0.5002 – 0.5893 – 0.6164 – – 0.6729 –
–
–
–0.452
1.964
–
–
–
–
–2.981
–0.343
–
–
4.920 – 1.505 – – 6.100 –
df
P
Odds ratio
1 2.948 1 3.696
1.106
– 7.857
–
–
1.164
11.731
–
–
1
.220
2.130
0.636
7.131
–
–
2.029E-12
0.000
0.000
–
–
1
.014
–
–
1
–
1 5.269 1
–
–
–
–
1.409
19.710
–
–
CI = confidence interval. *Dependent variable: implants lost per patient; model: (intercept), age, sex, bone graft, etiology, radiotherapy; offset = total implants placed per patient.
Fig 5 Intraoral view of the customized milled titanium bar. The overwhelming discrepancy between the occlusal plane and the implant shoulder indicated the unbalanced implant-abutment ratio, which was a risk factor for long-term success.
patients are not willing to receive additional implant surgeries. However, the procedure is still controversial, because primary implant insertions could result in unexpected and unfavorable occlusal relationships between the reconstructed mandible and the maxilla. The periosteal blood supply is disturbed, which compromises the bone graft consolidation and mucosa healing.27 Furthermore, in cancer-resected patients, there is the risk of tumor recurrence, which requires sufficient postoperative observation. Within the authors’ limited experience, careful treatment time selection and weighing of the disadvantages against
the benefits of primary implant insertion is of great importance. Following consideration of the long-term prosthetic results, a minimal interval of 6 months between mandible reconstruction and implant insertion is preferred in the authors’ department. Computer-guided graft and implant placement have gained a great deal of popularity during the last decade. With CT-guided surgery, the implants are placed exactly where virtually planned. There is little room for error when a computer-guided surgical template is seated precisely with anchor pins. However, there are concerns that have been raised by many authors regarding fibula free flap surgery. Most cancer patients require combined bone and soft tissue grafting. Currently, only bony defects can be assessed precisely, but prediction of soft tissue alteration cannot reflect the precise intraoperative and postoperative changes, such as inflammation and edema. Therefore, combined hard and soft tissue defects must always be considered and treated by overcorrection under visual feedback. Shallow vestibules and bulky flaps are common in reconstructed oral cancer and trauma patients. The thick subcutaneous tissue impedes dental prosthesis retention and is regarded as a potential risk factor for peri-implant mucositis. Recurrent soft tissue irritations can lead to unpredictable implant prognosis (Fig 6). A prerequisite for maintaining the function of dental implants is the presence of adequate keratinized soft tissue to serve as a barrier at the implant-gingiva junction. Furthermore, resection of osseous structures is often combined with resection of keratinized tissue, leaving the remnant keratinized soft tissue insufficient.
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Debulking of flaps, using palatal grafts or STSGs, has been proposed with various merits and drawbacks. Palatal grafts, which are routinely used for soft tissue grafting in esthetic regions, might not fit the dimensions of defects in cancer or trauma patients. STSGs, due to the varied selection of donor sites and flexible thickness, are preferred. The previously reported twostage submerged STSG technique has become a routine technique for keratinized soft tissue deficiencies in the authors’ department. In this two-stage technique, the STSG is placed beneath the bulky flap in the stageone surgery. The hypothesis of the technique was that the risk of STSG infection could be reduced by isolating the skin graft and the oral cavity. In addition, nutrition needed by the graft could be supplied by the underlying periosteum and the surrounding tissue fluids. However, there were controversies, as these substitutes differed from mucosa around natural teeth. Oral mucosa had fewer wrinkles, no appendages, more moisture, and deeper pigmentation.20 These characteristics can lead to changes in peri-implant conditions and might explain why implants in reconstructed mandibles were more susceptible to peri-implant inflammation. Prosthetic restoration in this study can be classified into two types: fixed and removable. Fixed prostheses feel much more effortless and comfortable compared with removable ones. From a biomechanical perspective, fixed prostheses apply constant and balanced occlusal stimulus to the residual bone, a process similar to that of natural dentition maintaining the marginal level of the alveolar bone. However, hygiene access to the circumferential tissue around the fixed prosthesis or crown is limited, and soft tissue irritations are prone to occur if scheduled maintenance is compromised. Fixed prostheses also require more implants, adding to the cost of the treatment plan. Removable prostheses can compensate for local soft tissue defects and lead to better esthetic outcomes. Additionally, implant stability and abutment screw loosening can be assessed during follow-up visits. Both types of restoration have their benefits and shortcomings and should be selected on a case-by-case basis. In some cancer patients, radiotherapy was inevitable. However, radiotherapy has been considered a contraindication to implant surgery because the capacity for osteogenesis is decreased, and osseointegration is impaired. Some studies showed that radiation doses exceeding 50 Gy could induce negative effects, including capillary thrombosis, osteoblast damage, and reduced vascularity.28,29 Nine patients in this study underwent adjuvant radiotherapy prior to implant placement. The implant survival rate during follow-up was lower than that of implants placed in nonirradiated bone. These figures were consistent with literature findings. It was believed that the implant survival rate
Fig 6 The “doughnut” lesion in peri-implant tissues.
in the cancer patient category was acceptable, considering the unfavorable environment for conventional removable prosthetic rehabilitation and the significant improvement in quality of life after treatment.
CONCLUSION This retrospective study showed that the functionality of implant-borne rehabilitation of fibula free flap– reconstructed patients was stable and predictable. Prosthetic-oriented and patient-specific treatment planning before surgery is of great importance. Regular follow-up visits and oral hygiene maintenance also contributed to the treatment successes.
ACKNOWLEDGMENTS The authors reported no conflicts of interest related to this study.
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