The use of computer-guided flapless dental implant surgery (NobelGuide) and immediate function to support a fixed full-arch prosthesis in fresh-frozen homologous patients with bone grafts.

The Journal of Craniofacial Surgery

& Volume 24, Number 6, November 2013

works of Heckmann et al22 and Zervas et al.30 Heckmann et al22 found that distortions caused by the impression procedures could be reduced by joining the metal structures and the prefabricated gold components directly in the experimental model, whereas Zervas et al30 observed that the welding process did not improve the adaptation of 3-unit implant-supported fixed partial prostheses.

CONCLUSIONS Within the limited conditions of this current study, the offset configuration of implants did not reduce the magnitude of microstrain around the implants under axial and nonYaxial loads, the location of the loading influenced the magnitude of microstrain around the implants, and loading on the nonYaxial point E (8 mm) generated an increase in the magnitude of microstrain around the implants.

REFERENCES 1. Lekholm U, Gro¨ndahl K, Jemt T. Outcome of oral implant treatment in partially edentulous jaws followed 20 years in clinical function. Clin Implant Dent Relat Res 2006;8:178Y186 2. Misch CE. Implant design considerations for the posterior regions of the mouth. Implant Dent 1999;8:376Y386 3. Rangert B, Jemt T, Jo¨rneus L. Forces and moments on Branemark implants. Int J Oral Maxillofac Implants 1989;4:241Y247 4. Rangert BR, Sullivan RM, Jemt TM. Load factor control for implants in the posterior partially edentulous segment. Int J Oral Maxillofac Implants 1997;12:360Y370 5. Duyck J, Van Oosterwyck H, Vander Sloten J, et al. Influence of prosthesis material on the loading of implants that support a fixed partial prosthesis: in vivo study. Clin Implant Dent Relat Res 2000;2:100Y109 6. C ¸ ehreli MC, Iplik0ioglu H, Bilir OG. The influence of the location of load transfer on strains around implants supporting four unit cement-retained fixed prostheses: in vitro evaluation of axial versus off-set loading. J Oral Rehabil 2002;29:394Y400 7. C ¸ ehreli MC, Iplik0ioglu H. In vitro strain gauge analysis of axial and off-axial loading on implant supported fixed partial dentures. Implant Dent 2002;11:286Y292 8. Barbier L, Schepers E. Adaptive bone remodeling around oral implants under axial and nonaxial loading conditions in the dog mandible. Int J Oral Maxillofac Implants 1997;12:215Y223 9. Barbier L, Vander Sloten J, Krzesinski G, et al. Finite element analysis of non-axial versus axial loading of oral implants in the mandible of the dog. J Oral Rehabil 1998;25:847Y858 10. Rangert B, Krogh PHJ, Langer B, et al. Bending overload and implant fracture: a retrospective clinical analysis. Int J Oral Maxillofac Implants 1995;10:326Y334 11. Sahin S, C ¸ ehreli MC, Yal0in E. The influence of functional forces on the biomechanics of implant-supported prosthesesVa review. J Dent 2002,30:271Y282 12. Frost MH. Wolff’s law and bone’s structural adaptations to mechanical usage: an overview for clinicians. Angle Orthod 1994;64:175Y188 13. Wiskott HWA, Belser UC. Lack of integration of smooth titanium surfaces: a working hypothesis based on strains generated in the surrounding bone. Clin Oral Implant Res 1999;10:429Y444 14. Sato Y, Shindoi N, Hosokawa R, et al. A biomechanical effect of wide implant placement and offset placement of three implants in the posterior partially edentulous region. J Oral Rehabil 2000;27:15Y21 15. Akca K, Iplik0ioglu H. Finite element stress analysis of the influence of staggered versus straight placement of dental implants. Int J Oral Maxillofac Implants 2001;16:722Y730 16. Itoh H, Caputo AA, Kuroe T, et al. Biomechanical comparison of straight and staggered implant placement configurations. Int J Periodontics Restorative Dent 2004;24:47Y55 17. Huang HL, Lin CL, Ko CC, et al. Stress analysis of implant-supported partial prostheses in anisotropic mandibular bone: in-line versus offset placements of implants. J Oral Rehabil 2006;33:501Y508

Brief Clinical Studies

18. Abu-Hammad O, Khraisat A, Dar-Odeh N, et al. The staggered installation of dental implants and its effect on bone stresses. Clin Implant Dent Relat Res 2007;9:121Y127 19. Nishioka RS, de Vasconcellos LG, de Melo Nishioka LN. External hexagon and internal hexagon in straight and offset implant placement: strain gauge analysis. Implant Dent 2009;18:512Y520 20. Nishioka RS, de Vasconcellos LG, de Melo Nishioka GN. Comparative strain gauge analysis of external and internal hexagon, morse taper, and influence of straight and offset implant configuration. Implant Dent 2011;20:e24Ye32 21. Mericske-Stern R, Assal P, Merickse E, et al. Oclussal force and oral tactile sensibility measured in partially edentulous patients with ITI implants. Int J Oral Maxillofac Implants 1995;10:345Y354 22. Heckmann SM, Karl M, Wichmann MG, et al. Cement fixation and screw retention: parameters of passive fit. An in vitro study of three-unit implant-supported fixed partial dentures. Clin Oral Implants Res 2004;15:466Y473 23. Karl M, Fischer H, Graef F, et al. Structural changes in ceramic veneered three-unit implant-supported restorations as a consequence of static and dynamic loading. Dent Mater 2008;24:464Y470 24. Suedam V, Souza EA, Moura MS, et al. Effect of abutment’s height and framework alloy on the load distribution of mandibular cantilevered implant-supported prosthesis. Clin Oral Implants Res 2009;20:196Y200 25. Lekholm U, Van Steenberghe D, Herrmann I, et al. Osseointegrated implants in the treatment of partially edentulous jaws: a prospective 5-year multicenter study. Int J Oral Maxillofac Implants 1994;9:627Y635 26. Jacques LB, Moura MS, Suedam V, et al. Effect of cantilever length and framework alloy on the stress distribution of mandibular-cantilevered implant-supported prostheses. Clin Oral Implants Res 2009;20:737Y741 27. Tashkandi EA, Lang BR, Edge MJ. Analysis of strain at selected bone sites of a cantilevered implant-supported prosthesis. J Prosthet Dent 1996;76:158Y164 28. Ak0a K, Kokat AM, Sahin S, et al. Effects of prosthesis design and impression techniques on human cortical bone strain around oral implants under load. Med Eng Phys 2009;31:758Y763 29. Vasconcellos LGO, Nishioka RS, Vasconcellos LM, et al. Effect of axial loads on implant-supported partial fixed prostheses by strain gauge analysis. J Appl Oral Sci 2011;19:610Y615 30. Zervas PJ, Papazoglou E, Beck FM, et al. Distortion of three-unit implant frameworks during casting, soldering, and simulated porcelain firings. J Prosthodont 1999;8:171Y179

The Use of Computer-Guided Flapless Dental Implant Surgery (NobelGuide) and Immediate Function to Support a Fixed Full-Arch Prosthesis in Fresh-Frozen Homologous Patients with Bone Grafts Pier Francesco Nocini, MD, DDS, Roberto Castellani, DDS, Guglielmo Zanotti, DDS, Dario Bertossi, MD, Umberto Luciano, DDS, Daniele De Santis, MD, DDS Abstract: The behavior of fresh-frozen homologous bone (FFB) when used in combination with computer-guided implant surgery has not been investigated yet, and there is a lack of clinical evidence

* 2013 Mutaz B. Habal, MD

Copyright © 2013 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

e551



in the literature. The purpose of this retrospective study is to evaluate the implant survival and related fixed full-arch prostheses at the 1- to 5-year follow-up when performed with immediate function using a flapless surgical procedure and computer-aided technology (NobelGuide; Nobel Biocare AB, Goteborg, Sweden) in patients previously treated with FFB grafts. Furthermore, the related values of torque and complications observed were analyzed and discussed. Clinical charts of patients with edentulous arches treated with FFB grafts and NobelGuide system with at least 1 year follow-up were reviewed retrospectively. A total of 65 patients met the criteria of inclusion, receiving a total of 342 implants and 77 full-arch prostheses, with a mean follow-up of 32.87 months (range, 1Y5 years). Survival of implants and prostheses was high, reaching 96.5% and 95%, respectively. Factors significantly related to failure of the implants were smoking, position of the implant as last distal abutment, and fracture of basal maxillary bone. Prostheses survival was influenced by bruxism, failure of multiple implants, and torque level of implant equal to 0 at implant insertion. All implants and prostheses failures occurred in the first year. A higher torque level at implant insertion did not correspond to a lower risk of implant failure. Within the limitations of our retrospective study, this treatment modality was predictable with high survival rates and high insertion torque. However, a few implant and prosthetic failures were found, together with several complications. Key Words: bone graft, computer-assisted surgery, dental implants, guided surgery, fresh-frozen bone

T

he introduction of computer-assisted and guided surgery has radically improved the possibility of using all available bone for implant support, reducing the need of extensive grafting procedures and allowing for a better restoration-driven implant placement, both in grafted and nongrafted sites.1 In fact, it is now possible to use the entire available osseous volume during the planning and the surgical phase, without the need for invasive grafting procedures. This approach allows for an accurate placement of implants using a flapless technique under the guidance of a surgical template generated from the preoperative virtual planning of the implant.1 In this way, precise implant installation is possible through a thick layer of soft tissues, having the drills and the implants guided by a computergenerated surgical guide. The planning is also useful to avoid obstacles or structures in the reconstructed bone such as screws, osteotomy sites, and discontinuity of bone segments.2 This technique has shown to be as successful as traditional implant surgery with flap access.3Y5 Moreover, the beneficial effect of flapless surgery without exposure of the periosteum may minimize bone resorption.6,7 However, a major prerequisite for a restoration-driven implant surgery still remains to be the availability of bone of adequate length and width, suitable for


the proper placement of implants of sufficient length. Physiologic resorption of the alveolar processes of the maxillary bones can lead to insufficient bone volume, especially in patients who have been edentulous for a long period, making it virtually impossible to place implants.8 A number of solutions have been proposed to obviate bone volume deficiency.2,9Y21 The end point of most of these techniques is the augmentation of available bone volume with onlay and inlay grafts.22Y25 Recently, the use of fresh-frozen homologous bone (FFB) grafts have shown good osteoconductive properties and biocompatibility with results comparable with those of autologous bone but with a reduced morbidity, lower surgical risk, and shorter operative time26 without modification of the traditional techniques.27Y37 Histologic studies have confirmed these results, showing the presence of new bone and osteoclast activity 4 months after grafting, with 80% mature bone observed after 12 months.38 Fresh-frozen homologous bone grafts resulted in volumes of bone similar to those obtained with autologous bone grafts; however, the amount of residual bone particles seems to be greater, which may indicate a slower remodeling process.39 The behavior of FFB when used in combination with computerguided implant surgery is still not well understood because studies are absent in the literature. The purpose of this retrospective cohort study was to evaluate the survival of implants and related fixed full-arch prostheses at the 1- to 5-year follow-up when performed with immediate function using a flapless surgical procedure and computer-aided technology (NobelGuide; Nobel Biocare AB, Goteborg, Sweden) in patients previously treated with FFB grafts.

MATERIALS AND METHODS Inclusion Criteria Clinical charts of patients with edentulous arches treated at the University of Verona with the NobelGuide system from January 2007 to December 2012 with at least 1 year of follow-up were reviewed. Patients’ medical history and clinical data were collected, together with panoramic radiographs and computed tomographic (CT) scans. The inclusion criteria used were the following: medical history negative for pathologies generally contraindicating implant surgery,40 initial edentulism, and previous preprosthetic surgery with application of fresh-frozen bone grafts to restore a sufficient bone volume for implant rehabilitation of the jaws. In particular, preprosthetic surgical treatment should have been carried out by the following techniques: 1. Ridge preservation with filling of the extraction sockets with bone chips (A).41 2. Posterior bilateral maxillary sinus augmentation with lateral window with bone chips (B)42,43 together with anterior maxillary bone block veneer surrounded by bone chips (C).28,30 3. Le Fort I osteotomy with inlay technique of Keller (D).26 In addition, all implant/prosthetic treatment and follow-up should have been carried out according to the NobelGuide protocol.1

From the Department of Surgical Sciences, Dental and Maxillofacial Department, University of Verona, Verona, Italy. Received March 3, 2013. Accepted for publication May 1, 2013. Address correspondence and reprint requests to Daniele De Santis, MD, DDS, Policlinico Borgo Roma, Clinica Odontoiatrica e di Chirurgia Maxillo-facciale, Piazzale Ludovico Antonio Scuro 10, 37134 Borgo Roma (VR), Italy; E-mail: [email protected] This article was funded by the authors’ institution. The authors report no conflicts of interest. Copyright * 2013 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0b013e31829ac8e2

e552

Grafting Material The material used in the preprosthetic surgical treatment was FFB. The FFB, obtained from the Veneto Tissue Bank in Treviso (Italy), is a mineralized, nonirradiated, and only disinfected, frozen homologous bone. The bone harvesting was obtained from the anterior and posterior iliac crest in the first 12 hours after donor death. The bone was then disinfected, for at least 72 hours at j4-C, in a polychemotherapeutic solution. The sample was then subdivided into corticomedullary blocks or morcellized, packed in double sterile casing, and frozen at j80-C.29 * 2013 Mutaz B. Habal, MD





Surgical Procedure

Statistical Analyses

Six months after FFB grafts, if plates or osteosynthesis screw were used, these were removed, and a temporary total or partial removable acrylic resin prosthesis was made. The NobelGuide procedure has been described previously for dentate and edentulous patients.10,12 Based on computer planning, a fixed metal-acrylic resin complete denture was constructed before the implant surgery and was immediately adapted and inserted after surgery. The technician inserted several gutta-percha markers (Hygienic; Colte`ne/Whaledent, Inc, Mahwah, NJ) in small holes with the diameter of 1.5 mm made in the prosthesis, as indicated by the NobelGuide protocol. The markers are necessary to the software (Procera or NobelClinician; Nobel Biocare AB) for coupling 2 CT scans: 1 of the patient and 1 of the prosthesis. Once the modifications on the denture were complete, it was possible to send the patient to a radiologic center where a double CT scan was carried out: 1 of the patient wearing the prosthesis/radiologic guide, correctly inserted, and 1 of the prosthesis alone. After 3-dimensional reconstruction of the CT images in the software, the Procera or NobelClinician software allowed us to plan the implant virtually according to the desired prosthetic result. The surgical operations were performed under local-regional anesthesia. The implants used were Bra˚nemark System MKIII (MKIII), Bra˚nemark System Groovy (Groovy) e NobelSpeedy Groovy (NobelSpeedy; Nobel Biocare AB) with an oxidized surface (TiUnite; Nobel Biocare AB). Once the template was stabilized using a surgical index and 3 anchor pins, the flapless implants were inserted, according to the drill sequence specific for the type of implant planned. The template was then removed, and the correct position of the implants was checked and temporary abutments were screwed in place. The prosthodontist relined a prefabricated provisional fixed metal-acrylic complete denture, including the temporary abutments in the prosthesis with resin and made it functional by adjusting occlusal contacts. One gram of amoxicillin/clavulanate (GlaxoSmithKline plc, Brentford, Middlesex, United Kingdom) every 12 hours for 6 days was prescribed. The patients were then dismissed. Sutures were removed after 15 days, and the patients were given oral hygiene instructions. The main follow-up appointments were delivery of the final fixed prostheses (6Y12 months), professional oral hygiene every 6 months, and regular control once a year to maintain good oral health and monitor the absence of complications and compliance with oral hygiene instructions. A radiographic evaluation (orthopantomogram or periapical radiograph of the implants) was performed each year.

Descriptive statistical analysis was performed, and cumulative survival rates were calculated for the implants and for the prostheses. Life table analyses were calculated according to the method of Cutler and Ederer.48 Because the values of variables were not normally distributed, statistical analysis was performed using nonparametric tests. In particular, the Wilcoxon-Mann-Whitney and KruskalWallis with Dunn multiple comparisons test were used, respectively, to evaluate if the torque differed significantly between the levels of a dichotomous (ie, sex, smoking) or polytomous (ie, type of implant or graft) variable. Spearman rank was used to evaluate the association between torque and quantitative variables (ie, age, length, diameter of the implant). Differences between proportions were tested with Fisher exact test, giving the odds ratio value when indicated. The implant or the prostheses was considered as the statistical unit.

RESULTS Characterization of the Population A total of 65 patients met the criteria of inclusion, receiving a total of 342 implants: 232 in the maxilla and 110 in the mandible. NobelSpeedy was inserted significantly more in the maxilla compared with MK III and Groovy (P G 0.001). The patients’ follow-up ranged from 1 to 5 years (mean, 32.87 months). The median age was 64 (interquartile range, 59Y69) years (minimum, 43; maximum, 78 years); 14 (21%) patients were male and received 65 implants, and 51 (79%) were females and received 277 implants. The median number of implants per prostheses was 4 (range, 4Y6). A total of 77 full-arch prostheses were made: 50 in the maxilla and 27 in the mandible. Seven patients (10.5%) were smokers (considered as current exposure to smoking at intake) and received a total of 30 implants. One hundred twenty-three implants (36%) were placed in areas treated with ridge preservation (A), 112 (32.7%) in areas treated with maxillary sinus augmentation with bone chips (B), 85 (24.8%) in areas treated with bone block veneer (C), and 22 (6.5%) in areas treated with Le Fort I osteotomy with inlay technique of Keller (D). Implant sites previously treated with ridge preservation (A) were mostly mandibular (110/123, 89.4%). Median torque was 40 N/cm (interquartile range, 35Y50). All implants placed in smokers and in the mandible had a torque of 30 N/cm or greater.

Implant Survival Clinical Assessment Implant survival was considered if these conditions were satisfied (from Malo` 2007 modified) 44: 1. Presence of the implant as planned in the NobelGuide treatment plan after surgery and during follow-up. 2. Clinical stability of the implant in the surrounding peri-implant bone at follow-up (bridge removed and implants individually checked). 3. Satisfactory function without any discomfort to the patient at follow-up. 4. No suppuration or infection present at follow-up. 5. No radiolucent areas around the implants at follow-up. Survival of the prosthesis was considered if all this conditions were met immediately after surgery and during the follow-up: 1. Presence in the mouth of the original prosthesis (in situ criterion).45 2. Presence of at least all the anterior teeth (for esthetics) and 2 posterior occlusal units (premolar/molar) for function46,47 as planned in the NobelGuide treatment plan.

Implant survival is described in Table 1. During the 1- to 5-year followup, 12 failures (3.5%) were detected. All the failures happened in the first year after NobelGuide surgery. The cumulative success rate was 96.5%. Detailed characterization of failures is presented in Table 2. Seven patients (10.7%) had at least a failure. One patient had 5 failures. The patient with 5 failures was a heavy smoker of up to 60 cigarettes a day treated with ridge preservation (A), but the failure was immediate because of fracture of the complete maxilla during implant placement, which precluded the possibility to proceed with the NobelGuide protocol: the implants had to be removed, and the maxilla, stabilized with osteosynthesis. Five of the failures were detected at implant placement, 1 was detected at 3 months, 3 at 6 months, and 3 at 12 months. The low number of failures precluded a detailed analysis of risk factors. Implants inserted in areas augmented with Le Fort I (D) and veneer (C) had no failures, whereas implant inserted in areas treated with ridge preservation (A) or sinus augmentation (B) had 7 and 5 failures, respectively. Failures had a tendency to be more frequent in the maxilla (4.3%) than in the mandible (1.8%), but the difference did



e553



TABLE 1. Life Table Analyses of Implants

Period, y 0Y1 1Y2 2Y3 3Y4 4Y5


TABLE 3. Life Table Analyses of Prostheses

Implants at Start of Interval, n

Failures During Interval, n

Interval Survival Rate, %

Cumulative Survival Rate, %

342 338 212 131 66

12 0 0 0 0

96.5 100 100 100 100

96.5 96.5 96.5 96.5 96.5

not reach statistical significance (P = 0.35). However, data showed that failures occurred more frequently in implants placed in smokers than in nonsmokers (P = 0.010; odds ratio, 12.7). Of 7 smokers, 2 (28.5%) had at least 1 failure. Only 5 (8.6%) of 58 nonsmokers experienced a failure. Implants placed as the final abutment of the prostheses were more likely to fail (P = 0.04; odds ratio, 3.8). Torque level at implant placement was not related to implant failure (P = 0.08).

Prostheses Survival Prostheses survival is described in Table 3. Of 77 full-arch fixed metal-acrylic prostheses, 4 (5%) failed during the follow-up. All of them were detected in the first year. As for implant failure, the low number of prosthetic failures precluded a detailed analysis of risk factors. In 1 patient, immediate loading of the implant was not possible. In fact, at implant insertion, 2 of 4 implants had torque equal to 0. These 2 implants were in the maxilla of the same patient, which had the other 2 implants with high insertion torque. This patient had to be rehabilitated initially with a complete denture. After 6 months healing of the implants, the patient was rehabilitated as planned. A second patient experienced fracture of the provisional prosthesis because of severe bruxism. A new metal-acrylic resin prosthesis was fabricated with a flat occlusal scheme. Implant failure led to prosthetic failure in 2 patients (ID 43 and ID 12) for the impossibility of having a sufficient number of implants for bearing a fixed prosthesis.

Torque Levels Values of torque were evaluated according to sex, age, smoking, type of implant, type of bone graft used to reconstruct the atrophic maxilla (Table 4), implant diameter, and length. Sex and age did not

Period, y 0Y1 1Y2 2Y3 3Y4 4Y5

Prostheses, n

Failures

Survival Rate, %

Cumulative Survival Rate, %

77 75 47 29 15

4 0 0 0 0

95 100 100 100 100

95 95 95 95 95

significantly affect the torque (P = 0.65 and P = 0.27, respectively). In smokers, implant insertion torque was significantly higher than in nonsmokers (P = 0.01). When considering all the implants, torque was significantly influenced by the type of implant used: NobelSpeedy achieved a significant lower torque compared with MKIII or Groovy (P G 0.0001). However, when considering only torque values of the implants placed in the mandible, this was not influenced by implant type (P = 0.58). Given that the median length of the implant inserted in the mandible was not different from the one in the maxilla (P = 0.17), implant length significantly affected insertion torque directly (P = 0.0001). This also held true when evaluating maxilla and mandible separately. Implant diameter significantly affected directly the insertion torque in the maxilla (P = 0.0004) but not in the mandible (P = 0.12). In reference to this, median diameter of implants placed in the maxilla was higher than in the mandible (P = 0.007). Implants located in the mandible had higher torque than in the maxilla (P G 0.0001). Implants inserted in areas where ridge preservation (A) was performed had a higher insertion torque compared with the other 3 grafting surgical procedures (P G 0.001). When considering only the upper jaw, the ridge preservation (A) had a higher torque compared with veneer (C) and Le Fort grafts (D) (P G 0.05), but there was no difference with sinus augmentation (B) (P 9 0.05). For the upper jaw, implants placed in grafted sinuses (B) were significantly longer than implants placed in Le Fort (D) or veneergrafted (C) areas (P G 0.05), whereas implants placed in veneer-grafted (C) areas were of significantly narrower diameter (P G 0.05). When evaluating implants of the same length placed in areas treated with different grafting procedures, the torque achieved did not differ significantly.

Miscellaneous Complications One patient experienced a fracture of the surgical stent in the mandible, which was repaired during the surgery. The position of 2 implants

TABLE 2. Characterization of Implant Failure Patient ID 12 12 31 40 43 43 43 43 43 52 56 58

Position

Most Distal Abutment

Sex

Age

Smoker

Diameter, mm

Length, mm

Implant Type*

Torque

Graft**

Months

14 24 26 16 12 14 22 24 26 14 44 44

Yes Yes Yes Yes No Yes No No Yes Yes Yes Yes

F F F F M M M M M F F F

57 57 57 63 72 72 72 72 72 43 78 71

No No No No Yes Yes Yes Yes Yes Yes No No

4 4 4 4 4 4 4 4 4 4 3,75 4

15 15 11.5 18 15 15 15 15 15 15 11,5 15

NobelSpeedy NobelSpeedy NobelSpeedy NobelSpeedy Groovy Groovy Groovy Groovy Groovy NobelSpeedy Groovy MK III

30 40 40 60 50 50 50 50 50 70 50 50

B B B B A A A A A B A A

6 6 12 12 0 0 0 0 0 3 6 12

*A, ridge preservation with bone chips; B, sinus augmentation with bone chips; C, block veneer; D, Le Fort I. **MKIII, Branemark System MKIII TiUnite; Groovy, Branemark System Groovy; NobelSpeedy, Nobelspeedy Groovy (Nobel Biocare AB, Goteborg, Sweden).

e554





TABLE 4. Value of Torque at Implant Insertion Related to Different Variables

Variables Sex Men Women Smoking habits Nonsmokers Current smokers Type of implant MK III Groovy MK III Ti Unite NobelSpeedy Location Maxilla Mandible Type of graft A B C D

Total n (n Maxilla)

Median (Interquartile Range)

P


bone graft (Le Fort I). All the patients had 6 posterior premolar/ molar units in the definitive prosthesis during the complete follow-up.

DISCUSSION

0.65 65 277

40 (40Y50) 40 (35Y50)

312 30

40 (35Y50) 50 (40Y60)

68 (5) 18 (0) 256 (227)

50 (50Y60)* 50 (45Y60)† 40 (30Y50)*†

232 110

40 (30Y50) 50 (45Y60)

123 112 85 22

50 40 35 35

0.01

(45Y60)*†‡ (30Y50)* (30Y40)† (30Y40)‡

G0.0001 G0.0001

G0.001

A, ridge preservation with bone chips; B, sinus augmentation with bone chips; C, block veneer; D, Le Fort I. *†‡Significant difference between groups. Wilcoxon-Mann-Whitney and KruskalWallis with Dunn’s multiple comparisons test.

in another patient was slightly aberrant from the planned position, resulting in a minor vestibular bone dehiscence at implant placement. The complication did not preclude achievement of sufficient torque, implant integration, and a favorable emergence profile for the final prosthesis. One patient experienced Le Fort I graft failure. After being treated with Le Fort I osteotomy with interposition of FFB (D), 6 months after NobelGuide surgical treatment, an incomplete healing of the maxillary basal bone in the area of the osteotomy with soft tissue interposition was detected. The patient was treated surgically, removing soft tissue from Le Fort osteotomy interface and stabilizing the bone once more with osteosynthesis. The prosthesis was removed, leaving the 6 osseointegrated implants in place with the surrounding bone without occlusal load. Six months after the procedure, the maxilla appeared well healed, and the prosthesis was placed back in occlusion with the opposing jaw. It should be highlighted that the implants together with the surrounding bone did not seem to be affected by the initial failure of the Le Fort I bone graft both clinically and radiographically. In 5 patients, implant failures (patient ID 31, 40, 52, 56, and 58) did not lead to prosthetic failure. In patient ID 40 and ID 31, after losing 1 of 6 implants in the molar position, a provisional and the definitive prosthesis with 6 occlusal units was still possible. In patient ID 52, 56, and 58 losing 1 distal implant and leaving only 3 implants resulted in a short provisional prosthesis with 2 occlusal units that, after reinsertion of a new implant in the same position as the one lost, led to the placement of a definitive prosthesis as planned with 6 occlusal units. The final numbers showed that 72 (93.5%) of 77 patients could have an immediate fixed functional provisional prosthesis with at least all the anterior teeth and 2 posterior premolar/molar units during the follow-up. As already mentioned, 1 patient experienced prosthetic failure (fracture of the prosthesis), 3 patients experienced implant-related failure (included 1 patient with fracture of basal bone), and 1 patient experienced a failure related to the previous

During the 1- to 5-year follow-up, 12 failures (3.5%) were detected. The cumulative survival rate was 96.5%. The low number of failures precluded a detailed analysis of risk factors. Failures had a tendency to be more frequent in the maxilla (4.3%) than in the mandible (1.8%), and all the failures happened in the first years after NobelGuide surgery, which has been shown previously in the literature.1 During the follow-up, implants placed in smokers were 12.7 times more likely to fail than implants placed in nonsmokers. The lower survival rate of implants placed in smokers has been well documented in the literature.49 In our study, implants placed as final abutment of the prostheses were 3.8 times more likely to experience a failure than interproximal implants. Failures of most distal abutment implants have already been shown in the literature after the standard ‘‘All-on-four’’ maxillary procedure50 and after NobelGuide treatment.51 This may be explained by the presence of a cantilever and of stress concentration in the most distal implant in the ‘‘All-on-four,’’ ‘‘All-on-six’’ model.52,53 Survival of implants placed in reconstructed bone with FFB in our study were comparable with those obtained with autologous bone grafts,54 FFB grafts,37 and NobelGuide treatment on native1,52 or fibula-reconstructed55 bone. In fact, it has been shown that the use of various dentoalveolar reconstructive procedures to reconstruct deficient implant recipient sites is not an independent risk factor for implant failure.56 However, in 1 patient, 5 implants failed because of fracture of the basal bone at implant placement. The reason for this is still unclear, but it may be speculated that the presence of a surgical stent in an atrophic maxilla may transfer the stress exerted by the implants on basal bone. This, together with the fact that no fracture of grafted bone surrounding the implant occurred in our patients, may indicate that complex implant/surrounding bone is safely stabilized by the stent but the resulting stress may be exerted outside the ferrule of the stent. Initial torque level at implant placement was not related to implant failure, but we have to take into account that 2 implants at torque 0 were left unloaded and that the implants were always included in a full-arch reconstruction. This can be explained in the light of the fact that it has been shown that higher insertion torque does not affect the bone-to-implant contact.57 Furthermore, torque level may not be a proper measurement of implant primary stability.58 Of 77 full-arch fixed prostheses, 4 (5%) failed during the followup. All of them were detected in the first year. Reasons for failure of the prostheses was in our study: torque 0 of the implants (1 case), fracture of the prostheses probably from bruxism (1 case), and failure of multiple implants (2 cases). Fracture of the prostheses is the most frequent cause of prosthetic failure in NobelGuide treatment and frequently related to bruxism.1 Unfortunately, in edentulous patients or partially edentulous patients with very few teeth, it is always difficult to diagnose bruxism.59 The remaining implant failures (3 cases) involved a single implant for each patient and did not lead to complete prosthetic failure. In these cases, the provisional prosthesis was shortened (although still having 2 occlusal units), and after reinsertion and integration of a new implant in the same position as the one lost, the patients were rehabilitated with a definitive prosthesis as planned (6 occlusal units). In our study, median values of torque reached are comparable with the values shown in the literature for native bone in the maxilla and mandible.60Y62 Sex and age did not influence torque values of inserted implants. In smokers, implant insertion torque was significantly higher than in nonsmokers. Implants located in the mandible had a higher torque than in the maxilla (P G 0.0001), which is in



e555



general agreement with the literature.62 NobelSpeedy achieved a significantly lower torque compared with MKIII or Groovy. This was unexpected because NobelSpeedy has been shown as an implant that may have higher primary stability.63 However, we have to emphasize that NobelSpeedy was used significantly more in the maxilla than in the mandible because of its morphology/design and that, when it was used in the mandible, it reached the same values of torque reached by the other 2 implant types. Based on these findings, we may explain the difference by taking into consideration the fact that maxillary bone is generally softer than mandibular bone resulting in lower torque values of mandibular implants compared with maxillary implants.62 Implant length significantly affected torque values directly both in the mandible and in the maxilla. This may be related to better mechanical stability of longer screws because insertion torque presents a direct relation with the length of the implant.64 Implant diameter influenced torque values directly in the maxilla, whereas in the mandible, the effect was less significant. This is even more important in combination with the fact that in the maxilla, implants of bigger diameter than in the mandible were inserted, approaching, but not equaling, torque levels reached in the mandible. It seems that the additional beneficial effect of an increase of diameter is more prominent in soft bone than in hard bone. However, we have to take into account that overpreparation of the implant site may counteract the benefit of an increased implant diameter.57 When evaluating maxilla and mandible together, implants inserted in areas where ridge preservation with filling of the extraction sockets with bone chips (A) was performed had a higher insertion torque compared with the other 3 grafting surgical procedures. This may be related to the fact that ridge preservation may imply a certain amount of native bone apically and interproximally (preserved bone walls), which may influence the healing process of the grafted bone and give the implant a mechanically more stable environment. When evaluating the upper jaw only, it appeared that implants placed in sinus-lifted areas were not affected by this behavior because implants placed in sinus lifted areas did not have different median torque values compared with implants placed in areas treated with ridge preservation. This may be explained by the fact that implants placed in sinus-lifted areas were significantly longer than implants placed in veneer- or Le Fort IYgrafted areas and, for this reason, have a higher torque value.58 In addition, they were wider than implants placed in veneer-grafted areas. Moreover, when evaluating implants of the same length placed in areas treated with different grafting procedures, the torque achieved did not differ significantly. So the higher torque in maxillary sinus-lifted areas may have been the result of a major bone improvement in quantity, and not in quality, available for implant placement after sinus lift compared with veneer or Le Fort I grafts. However, it has to be noted that this increase in torque, length, or diameter of distal upper implants did not seem to lead to a better survival because they seemed to be more prone to failure. The fact that an increase in length or diameter does not independently give a better survival of the implants has already been shown.65 Torque level at implant placement was not related to implant failure, which has been shown in previous publications.66,67 One patient experienced a fracture of the surgical stent in the mandible, which was repaired during the surgery. Fracture of the surgical stent has already been described as a possible complication that can be related to insufficient thickness or imperfect fitting of the stent in relation to the amount of stress generated by implant insertion.68 In another patient, the position of 2 implants deviated slightly from the planned position. This complication did not preclude achievement of sufficient torque, implant integration, and a favorable emergence profile for the final prostheses. An individual error can occur at each step of the guided surgery protocol, starting from the radiographic guide to the placement of the implant leading to incorrect implant placement.69 In particular, stereolithographic

e556


surgical guide stents have the potential to be dissimilar from the original scan denture. The isovalue threshold setting in the conversion software is a very sensitive component of the production process.70 Le Fort I graft failure is sometimes possible, resulting in the prevention of implant placement.71 In our study, 1 patient experienced incomplete healing of the osteotomy site, which was evident several weeks after the insertion of the implants. This patient was operated on again with a second Le Fort I, which was successful. It should be stressed that the presence of teeth in the fixed prostheses facilitated the process of stabilizing the maxilla to the basal bone during the operation. After healing, the same prosthesis was placed back in occlusion with the opposing jaw. Of importance is the fact that the implants together with the surrounding bone did not seem to be affected by the initial failure of the Le Fort I bone graft both clinically and radiographically. Of 77 patients, 72 (93.5%) were able to have a fixed functional provisional prostheses with at least all the anterior teeth and 2 posterior premolar/molar units. One patient experienced prosthetic failure (fractured prosthesis), 3 patients experienced implant-related failure, and 1 patient experienced graft-related failure (incomplete healing of Le Fort I). Two implant-related prosthetic failures could have probably been prevented in these patients by inserting more than the minimum of 4 implants. Given the fact that, in a grafted maxilla, failures are possible, especially in distal implants and in smokers, we would recommend that smoking cessation and the placement in the maxilla of more than the minimum of 4 implants may be indicated. This approach should maximize prosthetic survival in the case of failure of 1 implant. This additional implant should be placed more distal if possible to contribute to bearing the load of the prosthesis and function as an abutment in case one of the implants is lost. After managing these complications, all the patients had 6 posterior premolar/molar units in the definitive prosthesis during the complete follow-up. Our findings also suggest strongly that we should not underestimate the stress generated by the complex implant/surgical guide. This stress may generate the fracture of the surgical stent or, in more unfavorable situation, the fracture of the basal bone. It is still unclear how to reduce this stress to a level of safety.

CONCLUSIONS Based on the results of our retrospective study, we can conclude the following: 1. Survival of implants was high, reaching 96.5% in a 1- to 5-year period. 2. Survival of the prostheses was high, reaching 95% in a 1- to 5-year period. 3. Factors significantly related to failure of the implants were smoking (odds ratio, 12.7) and most distal position of the implant (odds ratio 3.8). 4. Prosthesis survival was influenced by bruxism, failure of multiple implants, torque level of implant equal to 0 at implant insertion, and fracture of basal maxillary bone. 5. All implant and prosthesis failures occurred in the first year. 6. Torque values at insertion were significantly higher in smokers, the mandible, long and wide implants, and ridge preservation techniqueYtreated sites. 7. A higher torque level at implant insertion did not correspond to a lower risk of implant failure. This study indicates that patients previously augmented with FFB graft for maxillary or mandibular bone atrophy can be safely treated with implant-supported prostheses based on the NobelGuide protocol, with the aid of a computer-generated guide. This procedure * 2013 Mutaz B. Habal, MD




may be a promising treatment option, offering several advantages to both clinicians and patients, while keeping the same degree of predictability in terms of torque levels, survival of the implants, and the prostheses compared with conventional treatment. However, in our study, only implant survival was analyzed, and the low number of implants and prosthetic failures precluded a detailed analysis of risk factors associated to these failures. Before drawing any general conclusion, the benefit of the procedure should be further evaluated by prospective clinical trials where the possible end points of the treatment, including more strict criteria of implant success, should be more thoroughly evaluated and compared with conventional protocols on the same study population.

ACKNOWLEDGMENT The authors thank Dr. Gordon N. Wolffe for reviewing the manuscript. REFERENCES 1. Malo P, de Araujo Nobre M, Lopes A. The use of computer-guided flapless implant surgery and four implants placed in immediate function to support a fixed denture: preliminary results after a mean follow-up period of thirteen months. J Prosthet Dent 2007;97:S26YS34 2. Nocini PF, Albanese M, Castellani R, et al. Application of the ‘‘All-on-Four’’ concept and guided surgery in a mandible treated with a free vascularized fibula flap. J Craniofac Surg 2012;23:e628Ye631 3. Balshi SF, Wolfinger GJ, Balshi TJ. A prospective study of immediate functional loading, following the Teeth in a Day protocol: a case series of 55 consecutive edentulous maxillas. Clin Implant Dent Relat Res 2005;7:24Y31 4. Balshi SF, Wolfinger GJ, Balshi TJ. Surgical planning and prosthesis construction using computer technology and medical imaging for immediate loading of implants in the pterygomaxillary region. Int J Periodontics Restorative Dent 2006;26:239Y247 5. van Steenberghe D, Glauser R, Blomback U, et al. A computed tomographic scanYderived customized surgical template and fixed prosthesis for flapless surgery and immediate loading of implants in fully edentulous maxillae: a prospective multicenter study. Clin Implant Dent Relat Res 2005;7:S111YS120 6. Fickl S, Kebschull M, Schupbach P, et al. Bone loss after full-thickness and partial-thickness flap elevation. J Clin Periodontol 2011;38:157Y162 7. Lee JH, Kim MJ, Choi WS, et al. Concomitant reconstruction of mandibular basal and alveolar bone with a free fibular flap. Int J Oral Maxillofac Surg 2004;33:150Y156 8. Tallgren A. The continuing reduction of the residual alveolar ridges in complete denture wearers: a mixed-longitudinal study covering 25 years. J Prosthet Dent 1972;27:120Y132 9. Bertele G, Mercanti M, Stella F, et al. Osteodistraction in the craniofacial region. Minerva Stomatol 2005;54:179Y198 10. De Santis D, Canton LC, Cucchi A, et al. Computer-assisted surgery in the lower jaw: double surgical guide for immediately loaded implants in postextractive sites-technical notes and a case report. J Oral Implantol 2010;36:61Y68 11. De Santis D, Cucchi A, Longhi C, et al. Short threaded implants with an oxidized surface to restore posterior teeth: 1- to 3-year results of a prospective study. Int J Oral Maxillofac Implants 2011;26: 393Y403 12. De Santis D, Malchiodi L, Cucchi A, et al. Computer-assisted surgery: double surgical guides for immediate loading of implants in maxillary postextractive sites. J Craniofac Surg 2010;21:1781Y1785 13. de Santis D, Trevisiol L, Cucchi A, et al. Zygomatic and maxillary implants inserted by means of computer-assisted surgery in a patient with a cleft palate. J Craniofac Surg 2010;21:858Y862 14. De Santis D, Trevisiol L, D’Agostino A, et al. Guided bone regeneration with autogenous block grafts applied to Le Fort I osteotomy for treatment of severely resorbed maxillae: a 4- to 6-year prospective study. Clin Oral Implants Res 2012;23:60Y69


15. Guerriero C, De Santis D, Nocini PF, et al. Tissue culture of adult human osteoblasts isolated from jaw bones. Ital J Anat Embryol 1995;100:83Y93 16. Nocini PF, Albanese M, Fior A, et al. Implant placement in the maxillary tuberosity: the Summers’ technique performed with modified osteotomes. Clin Oral Implants Res 2000;11:273Y278 17. Nocini PF, De Santis D, Ferrari F, et al. A customized distraction device for alveolar ridge augmentation and alignment of ankylosed teeth. Int J Oral Maxillofac Implants 2004;19:133Y144 18. Springer IN, Nocini PF, Schlegel KA, et al. Two techniques for the preparation of cell-scaffold constructs suitable for sinus augmentation: steps into clinical application. Tissue Eng 2006;12:2649Y2656 19. Branemark PI, Adell R, Albrektsson T, et al. An experimental and clinical study of osseointegrated implants penetrating the nasal cavity and maxillary sinus. J Oral Maxillofac Surg 1984;42:497Y505 20. Chiapasco M, Romeo E, Vogel G. Tridimensional reconstruction of knife-edge edentulous maxillae by sinus elevation, onlay grafts, and sagittal osteotomy of the anterior maxilla: preliminary surgical and prosthetic results. Int J Oral Maxillofac Implants 1998;13:394Y399 21. Raviv E, Turcotte A, Harel-Raviv M. Short dental implants in reduced alveolar bone height. Quintessence Int 2010;41:575Y579 22. Felice P, Marchetti C, Iezzi G, et al. Vertical ridge augmentation of the atrophic posterior mandible with interpositional bloc grafts: bone from the iliac crest vs. bovine anorganic bone. Clinical and histological results up to one year after loading from a randomized-controlled clinical trial. Clin Oral Implants Res 2009;20:1386Y1393 23. Felice P, Marchetti C, Piattelli A, et al. Vertical ridge augmentation of the atrophic posterior mandible with interpositional block grafts: bone from the iliac crest versus bovine anorganic bone. Eur J Oral Implantol 2008;1: 183Y198 24. Lekholm U, Wannfors K, Isaksson S, et al. Oral implants in combination with bone grafts. A 3-year retrospective multicenter study using the Branemark implant system. Int J Oral Maxillofac Surg 1999;28:181Y187 25. Perry RT. Ascending ramus offered as alternate harvest site for onlay bone grafting. Dent Implantol Update 1997;8:21Y24 26. Nocini PF, Bertossi D, Albanese M, et al. Severe maxillary atrophy treatment with Le Fort I, allografts, and implant-supported prosthetic rehabilitation. J Craniofac Surg 2011;22:2247Y2254 27. Accetturi E, Germani KB, Cavalca D. Reconstruction of bone defects in the maxilla and mandibula through the use of frozen human bone. Transplant Proc 2002;34:531Y533 28. Barone A, Varanini P, Orlando B, et al. Deep-frozen allogeneic onlay bone grafts for reconstruction of atrophic maxillary alveolar ridges: a preliminary study. J Oral Maxillofac Surg 2009;67:1300Y1306 29. Carinci F, Brunelli G, Zollino I, et al. Mandibles grafted with fresh-frozen bone: an evaluation of implant outcome. Implant Dent 2009;18:86Y95 30. Contar CM, Sarot JR, Bordini J Jr, et al. Maxillary ridge augmentation with fresh-frozen bone allografts. J Oral Maxillofac Surg 2009;67: 1280Y1285 31. Franco M, Tropina E, De Santis B, et al. A 2-year follow-up study on standard length implants inserted into alveolar bone sites augmented with homografts. Stomatologija 2008;10:127Y132 32. Franco M, Viscioni A, Rigo L, et al. Iliac crest fresh frozen homografts used in pre-prosthetic surgery: a retrospective study. Cell Tissue Bank 2009;10:227Y233 33. Franco M, Viscioni A, Rigo L, et al. Clinical outcome of narrow diameter implants inserted into allografts. J Appl Oral Sci 2009;17: 301Y306 34. Grecchi F, Zollino I, Parafioriti A, et al. One-step oral rehabilitation by means of implants’ insertion, Le Fort I, grafts, and immediate loading. J Craniofac Surg 2009;20:2205Y2210 35. Perrott DH, Smith RA, Kaban LB. The use of fresh frozen allogeneic bone for maxillary and mandibular reconstruction. Int J Oral Maxillofac Surg 1992;21:260Y265 36. Viscioni A, Franco M, Rigo L, et al. Implants inserted into homografts bearing fixed restorations. Int J Prosthodont 2009;22:148Y154 37. Viscioni A, Franco M, Rigo L, et al. Retrospective study of standard-diameter implants inserted into allografts. J Oral Maxillofac Surg 2009;67:387Y393



e557



38. Viscioni A, Dalla Rosa J, Paolin A, et al. Fresh-frozen bone: case series of a new grafting material for sinus lift and immediate implants. J Ir Dent Assoc 2010;56:186Y191 39. Pelegrine AA, Sorgi da Costa CE, Sendyk WR, et al. The comparative analysis of homologous fresh frozen bone and autogenous bone graft, associated or not with autogenous bone marrow, in rabbit calvaria: a clinical and histomorphometric study. Cell Tissue Bank 2011;12:171Y184 40. Lekolm U, Zarb GA. Patient selection and preparation. In: Branemark P-I, Zarb GA, Albrektsson T, eds. Tissue-Integrated Prostheses: Osseointegration in Clinical Dentistry. Chicago: Quintessence, 1985:211Y232 41. Araujo MG, Lindhe J. Socket grafting with the use of autologous bone: an experimental study in the dog. Clin Oral Implants Res 2011;22:9Y13 42. Acocella A, Bertolai R, Nissan J, et al. Clinical, histological and histomorphometrical study of maxillary sinus augmentation using cortico-cancellous fresh frozen bone chips. J Craniomaxillofac Surg 2011;39:192Y199 43. Avila G, Neiva R, Misch CE, et al. Clinical and histologic outcomes after the use of a novel allograft for maxillary sinus augmentation: a case series. Implant Dent 2010;19:330Y341 44. Malo P, de Araujo Nobre M, Rangert B. Short implants placed one-stage in maxillae and mandibles: a retrospective clinical study with 1 to 9 years of follow-up. Clin Implant Dent Relat Res 2007;9:15Y21 45. Frisch E, Ziebolz D, Rinke S. Long-term results of implant-supported over-dentures retained by double crowns: a practice-based retrospective study after minimally 10 years follow-up. Clin Oral Implants Res [published online ahead of print Aug 6, 2012] doi: 10.1111/j.1600-0501. 2012.02568.x 46. Kayser AF. Shortened dental arches and oral function. J Oral Rehabil 1981;8:457Y462 47. Witter DJ, Cramwinckel AB, van Rossum GM, et al. Shortened dental arches and masticatory ability. J Dent 1990;18:185Y189 48. Cutler SJ, Ederer F. Maximum utilization of the life table method in analyzing survival. J Chronic Dis 1958;8:699Y712 49. Liddelow G, Klineberg I. Patient-related risk factors for implant therapy. A critique of pertinent literature. Aust Dent J 2011;56:417Y426; quiz 441 50. Parel SM, Phillips WR. A risk assessment treatment planning protocol for the four implant immediately loaded maxilla: preliminary findings. J Prosthet Dent 2011;106:359Y366 51. Pomares C. A retrospective study of edentulous patients rehabilitated according to the ‘all-on-four’ or the ‘all-on-six’ immediate function concept using flapless computer-guided implant surgery. Eur J Oral Implantol 2010;3:155Y163 52. Silva GC, Mendonca JA, Lopes LR, et al. Stress patterns on implants in prostheses supported by four or six implants: a three-dimensional finite element analysis. Int J Oral Maxillofac Implants 2010;25:239Y246 53. Kim P, Ivanovski S, Latcham N, et al. The impact of cantilevers on biological and technical success outcomes of implant-supported fixed partial dentures. A retrospective cohort study. Clin Oral Implants Res [published online ahead of print Jan 2, 2013] doi: 10.1111/clr.12102 54. Aghaloo TL, Moy PK. Which hard tissue augmentation techniques are the most successful in furnishing bony support for implant placement? Int J Oral Maxillofac Implants 2007;22:49Y70 55. De Riu G, Meloni SM, Pisano M, et al. Computed tomography-guided implant surgery for dental rehabilitation in mandible reconstructed with a fibular free flap: description of the technique. Br J Oral Maxillofac Surg 2012;50:30Y35 56. Woo VV, Chuang SK, Daher S, et al. Dentoalveolar reconstructive procedures as a risk factor for implant failure. J Oral Maxillofac Surg 2004;62:773Y780 57. Pantani F, Botticelli D, Garcia IR Jr, et al. Influence of lateral pressure to the implant bed on osseointegration: an experimental study in dogs. Clin Oral Implants Res 2010;21:1264Y1270 58. Degidi M, Daprile G, Piattelli A, et al. Evaluation of factors influencing resonance frequency analysis values, at insertion surgery, of implants placed in sinus-augmented and nongrafted sites. Clin Implant Dent Relat Res 2007;9:144Y149 59. Gealh WC, Mazzo V, Barbi F, et al. Osseointegrated implant fracture: causes and treatment. J Oral Implantol 2011;37:499Y503

e558


60. Friberg B, Jisander S, Widmark G, et al. One-year prospective three-center study comparing the outcome of a ‘‘soft bone implant’’ (prototype Mk IV) and the standard Branemark implant. Clin Implant Dent Relat Res 2003;5:71Y77 61. Turkyilmaz I. A comparison between insertion torque and resonance frequency in the assessment of torque capacity and primary stability of Branemark system implants. J Oral Rehabil 2006;33:754Y759 62. Fuster-Torres MA, Penarrocha-Diago M, Penarrocha-Oltra D, et al. Relationships between bone density values from cone beam computed tomography, maximum insertion torque, and resonance frequency analysis at implant placement: a pilot study. Int J Oral Maxillofac Implants 2011;26:1051Y1056 63. Tallarico M, Vaccarella A, Marzi GC, et al. A prospective case-control clinical trial comparing 1- and 2-stage Nobel Biocare TiUnite implants: resonance frequency analysis assessed by Osstell Mentor during integration. Quintessence Int 2011;42:635Y644 64. Hong J, Lim YJ, Park SO. Quantitative biomechanical analysis of the influence of the cortical bone and implant length on primary stability. Clin Oral Implants Res 2012;23:1193Y1197 65. Renouard F, Nisand D. Impact of implant length and diameter on survival rates. Clin Oral Implants Res 2006;17:35Y51 66. Norton MR. The influence of insertion torque on the survival of immediately placed and restored single-tooth implants. Int J Oral Maxillofac Implants 2011;26:1333Y1343 67. Rodrigo D, Aracil L, Martin C, et al. Diagnosis of implant stability and its impact on implant survival: a prospective case series study. Clin Oral Implants Res 2010;21:255Y261 68. Merli M, Bernardelli F, Esposito M. Computer-guided flapless placement of immediately loaded dental implants in the edentulous maxilla: a pilot prospective case series. Eur J Oral Implantol 2008;1:61Y69 69. Vercruyssen M, Jacobs R, Van Assche N, et al. The use of CT scan based planning for oral rehabilitation by means of implants and its transfer to the surgical field: a critical review on accuracy. J Oral Rehabil 2008;35:454Y474 70. Stumpel LJ. Deformation of stereolithographically produced surgical guides: an observational case series report. Clin Implant Dent Relat Res 2012;14:442Y453 71. Chiapasco M, Brusati R, Ronchi P. Le Fort I osteotomy with interpositional bone grafts and delayed oral implants for the rehabilitation of extremely atrophied maxillae: a 1Y9-year clinical follow-up study on humans. Clin Oral Implants Res 2007; 18:74Y85

Quality of Life in Patients Younger Than 40 Years Treated for Anterior Tongue Squamous Cell Carcinoma Xu Zhang, MS,*Þ Qi-Gen Fang, MS,*Þ Zhen-Ning Li, MS,*Þ Wen-Lu Li, MS,*Þ Fa-Yu Liu, MD,*Þ Chang-Fu Sun, MD*Þ Abstract: This study investigated the quality of life in patients younger than 40 years with tongue squamous cell carcinoma. We used the University of Washington Head and Neck Quality of Life scale to compare the quality of life outcomes between young and old patients. Cases were patients younger than 40 years who were treated for anterior tongue squamous cell carcinoma. Controls were patients older than 40 years who were matched to the cases regarding diagnosis, sex, and TNM classification. Two controls were matched * 2013 Mutaz B. Habal, MD


Flapless versus conventional flapped dental implant surgery: a meta-analysis.

Attachment-retained gingival prosthesis for implant-supported fixed dental prosthesis in the maxilla: a clinical report.

Using the "final-on-four" concept to deliver an immediate metal-resin implant-fixed complete dental prosthesis.

Paranasal bone: the prime factor affecting the decision to use transsinus vs zygomatic implants for biomechanical support for immediate function in maxillary dental implant reconstruction.

Transition from a fixed implant dental prosthesis to an implant overdenture in an edentulous patient: a clinical report.

Flapless dental implant surgery: a retrospective study of 1,241 consecutive implants.

An alternative technique for fabrication of frameworks in an immediate loading implant fixed mandibular prosthesis.

Model-Guided Flapless Immediate Implant Placement and Provisionalization in the Esthetic Zone Utilizing a Nanostructured Titanium Implant: A Case Report.

The use of bone-chip grafts fixed with absorbable bone sealant (Absele).

CAM-fabricated, implant-supported fixed dental prosthesis: a clinical report.

Digital process for an implant-supported fixed dental prosthesis: A clinical report.

Photoelastic analysis of fixed partial prosthesis crown height and implant length on distribution of stress in two dental implant systems.

Dental extraction, immediate placement of dental implants, and immediate function.

Bone-implant contact around crestal and subcrestal dental implants submitted to immediate and conventional loading.

Computer-assisted flapless implant surgery in edentulous elderly patients: a 2-year follow up.

Replacement of a mandibular implant-fixed prosthesis with an implant-supported overdenture to improve maintenance and care.

A modified design for posterior inlay-retained fixed dental prosthesis.

Complications and patient-centered outcomes with an implant-supported monolithic zirconia fixed dental prosthesis: 1 year results.

Piezosurgery-assisted, flapless split crest surgery for implant site preparation.

Immediate versus early loading of flapless placed dental implants: a systematic review.

Stress Distribution in Bone and Implants in Mandibular 6-Implant-Supported Cantilevered Fixed Prosthesis: A 3D Finite Element Study.

Stabilization of a computer-aided implant surgical guide using existing dental implants with conversion of an overdenture to a fixed prosthesis.

Restorative considerations for a fixed implant prosthesis using different root form implant systems.

Subcrestal Implant Placement.