Journal of Oral Implantology Implant-guided vertical bone augmentation around extra-short implants for the management of severe bone atrophy --Manuscript Draft-Manuscript Number:
AAID-JOI-D-13-00131R1
Full Title:
Implant-guided vertical bone augmentation around extra-short implants for the management of severe bone atrophy
Short Title:
Implant-guided bone augmentation
Article Type:
Clinical Research
Keywords:
vertical bone augmentation, bone atrophy, autologous bone, low-speed drilling, short implants, extra-short implants
Corresponding Author:
GORKA ORIVE, Pharmacy University of the Basque Country Vitoria, ALAVA SPAIN
Corresponding Author Secondary Information: Corresponding Author's Institution:
University of the Basque Country
Corresponding Author's Secondary Institution: First Author:
Eduardo Anitua
First Author Secondary Information: Order of Authors:
Eduardo Anitua Alia Murias-Freijo Mohammad Alkhraist GORKA ORIVE, Pharmacy
Order of Authors Secondary Information: Abstract:
The purpose of this study is to describe the conservative treatment of severe vertical bone atrophy by combining the insertion of extra-short implants and implant-guided bone augmentation. For that, low-speed drilling protocol was selected to facilitate the collection of bone particles and to maintain graft osteogenic properties. Extra-short implants were incompletely inserted due to the severe atrophy and the denuded implant surface was covered by autologous bone particles held together by the adhesive properties of plasma rich in growth factors. The surgical site was then covered with resorbable fibrin membrane and the flap was repositioned and sutured. Eight patients with a mean residual bone height of 4.19 ± 0.97 mm were treated according to the described treatment protocol. The distance between the implant shoulder and the bony crest was 1.77 ± 0.18, 2.16 ± 0.23, and 1.97 ± 0.26 mm at mesial, central and distal, respectively. Vertical bone augmentation resulted in the coverage of the 85% of exposed surface by stimulating 1.6 ± 0.5 mm of supra-alveolar bone growth. All placed Extra-short implants were successfully osteointegrated (10/10). After 5 ± 1.6 months, provisional screw-retained prostheses were placed. Within the limitations of this study, we conclude that the minimally invasive approach described in this study may successfully rehabilitate extreme vertical bone atrophy in the posterior mandible.
Response to Reviewers:
Editor-in-Chief Journal of Oral Implantology Dear Dr. James Rutkowski, DMD, PhD We deeply acknowledge the reviewers for the careful and detailed reading of the
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manuscript and also evaluate the comments and questions formulated to improve our manuscript. We have addressed every comment that the reviewers have made and hope to answer adequately their inquiries. Below, we detail our answers to the reviewers and inform that all changes have been marked within the manuscript. Kind regards, [removed for blinding purposes] Reviewers' comments: Reviewer #1: Dear author(s), I found the submitted manuscript to be of interest and relevance to the scope of the JOI. It describes and interesting technique for the rehabilitation of the atrophic posterior mandible. - We are thankful for the detailed analysis of the manuscript and the careful reading of the manuscript. The reviewer notes were very helpful to improve the manuscript. However, I have identified several areas that need to be clarified before the manuscript is appropriate for publication. The major areas of concern are underlined in the suggestions listed in the attached document. - All the listed suggestions have addressed adequately and changes have been done accordingly. Title: •Please consider using ‘’augmentation’’ instead of ‘’growth’’ as a more appropriate term Authors: Done Short title: •same in lieu of ‘’formation’’. Authors: Done Abstract: •Please change the sentence to :’’Eight patients with a mean residual bone height of 4.19 ± 0.97 mm’’ Authors: Done •You can add the word ‘’, respectively’’ at the end of the sentence: ‘’The distance between the implant shoulder and the bony crest was 1.77 ± 0.18, 2.16 ± 0.23, and 1.97 ± 0.26 mm at mesial, central and distal…’’ for ease of understanding by the reader. Authors: Done •‘’ by stimulating about 2 mm of supra-alveolar bone growth’’, Consider providing the specific mean of vertical bone augmentation followed by the standard deviation estimated instead of simply reporting the rounded number ‘’2mm’ Authors: The exact value is now provided "1.6 ± 0.5 mm of supra-alveolar bone growth" •‘’Extra-short implants were successfully osteointegrated and gave support to provisional screw-retained prostheses.’’: You may want to consider reporting your results more distinctly. It should be stated that all placed implants successfully osseointegrated; consider adding the proportion of placed to osseointegrated implants (10/10). Also mention when the provisional restorations were placed. Authors: Done •Please add that your conclusion is stated ‘’within the limitations of this study’’. Also consider changing ‘’paper’’ to ‘’study’’ or another term that can be used for scientific papers. Authors: Done Introduction: • 25: A single edentulous site may be severely resorbed and still the technique reported would be applicable. I feel that it will be more accurate to change ‘’jaw’’ to Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation
‘’edentulous ridges’’, or another similar term. Authors: Done •26-27: Autologous bone blocks are one of many alternatives for vertical bone augmentation. You can either reference additional alternatives to provide the reader with a better understanding of the currently used techniques for vertical bone augmentation, or rephrase to explain that this is only one of many options. Authors: Done •32: Please change ‘’encompass’’ to a more appropriate term. Authors: Done •34: Please change ‘’the first’’ with ‘’initially’’ Authors: Done •35:’’proven’’ •36:Please change to: ‘’even after long periods of function’’ Authors: Done •38: ‘’ratio’’ Authors: Done •40: re-consider the use of ‘’jaw’’ Authors: Done •40: Citations with authors name in text should come with date indicated in parenthesis. Please add the year of the publication for ease of reference. E.g. Anitua et al. (2013) Authors: Done •42:’’another’’ instead of ‘’other’’ Authors: Done •42-44: How long was the follow-up? ‘‘Long’’ can be changed to ‘’conventional’’ or ‘’standard’’. Please specify if ‘’6.3mm’’ refers to their length. Authors: Done •48: How did you specify the number ‘’2-3mm’’. Do you exclude less than 2mm? Authors: the phrase have been removed. •49: Please delete ‘’it’’ Authors: Done •53: ‘’filling’’ can be changed to a more appropriate term. Authors: Done •55:’’enhanced’’ Authors: Done •60: by ‘’covered’’ you mean on the outside, or do you mean separated? Authors:" was covered on the outside by a thick layer of connective tissue29". •56-60: These findings, although important to report, are not studied in your investigation. Thus, it would be more appropriate to consider moving them to the discussions section. Authors: Done •62:Please change to : ‘’posterior mandibular sites’’ Authors: Done •62: See previous comment. ‘‘Filling material’’ is not a scientifically valid term for bone grafts used for vertical bone augmentation and changing it to a more relevant term would be of benefit. Authors: "grafting material" is now provided •64. Consider changing ‘’,’’ to a full stop and starting a new sentence to describe the fibrin membrane you used for coverage. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation
Authors: done •The introduction is lacking report of specific aims for this study. I suggest you distinctly report the aims of the study in the last paragraph of the introduction. Authors: "Thus, this study aims to evaluate surgical complications that may occur after the performance of the described technique and also evaluate the amount of vertical bone augmentation that is achieved around the dental implants". M&M •67. ‘’Patients data base’’ Is this database coming from a private clinic, multiple clinics? A hospital setting? Authors: "Patients data base from a private clinic". •84: Please provide a reference for ‘’biological’’ low-speed drilling. Authors: done •87: You state that ‘’The drilling procedure was divided in two phases: the first phase uses conventional drills and the working length was set 1 mm shorter than the total length of the implant bed ‘’ and then you report that the distance from the crest to the implant shoulder is ~2mm depending on the surface. I did not understand how the distance is approximately 2mm if you drilled only 1mm shorter of the total length. Did you mean 1mm shorter of the already reduced implant length? Authors: - The first sentence refer to the drilling procedure that is done before the insertion of the dental implant. For example if we have residual bone height of 4 mm, then the working length of conventional drill is 3 mm and the last 1 mm is drilled with frontal cutting drill. - The second sentence refer to the part of implant surface that is exposed after implant insertion in the bone. For example if 5.5 mm-long implant is placed in residual bone height of 4 mm then 1.5 mm of implant will be exposed (distance between implant shoulder and bone crest) •99: PRGF seems to be an important aspect of your suggested treatment, but is first reported here. I suggest adding some data in regards to the benefits of using PRGF in this case and for justification of its use in the introduction section. A photograph of the autologous particles in the fibrin mesh would be of great interest. Authors: done •120: correct ‘’evolution’’ Authors: "Clinical evaluation". •125-126: Appropriate statistical analysis is very important to validate the accuracy of your results. You have stated that: ‘’t-student test was applied to analyze the statistical significant of the difference between both measurements. ‘’ In the literature, the term ‘’t-test’’, or ‘’student’s t-test’’ is used to describe an ‘’unpaired t-test’’. In your case you have compared numerical data pre-operatively and postoperatively in the same patients. Therefore a ‘’paired t-test’’ is the appropriate statistical test, based on the hypothesis that your data come from a normally distributed pool. I suggest that, if you have already used a ‘’paired t-test’’ you explicitly mention that. Otherwise, I recommend performing the analysis using an‘’unpaired t-test’’. I also encourage you to report the P-value obtained for each comparison in the results section to distinctly show that your results are statistically significant. Authors: the following corrections have been done to the statistical analysis in the materials and methods section: "Normality test (Shapiro-Wilk) was applied to verify if data followed a normal distribution. Paired t-student test...". The differences were statistically significant between measurements before and after surgery. Results •132: Consider using ‘’fulfilled’’ instead of ‘’completed’’. Authors: done •133: Add ‘’to’’ following ‘’due’’ Authors: done •139: In scientific texts, use the correct terms, if available. I suggest using the term “Cone beam computed tomography’’, or ‘’cone beam volumetric tomogram’’. Authors: done •143: The insertion torque is a finding of interest. Please add information on how you evaluated that in the materials and methods section. Authors: The following phrases have been added to the materials and methods section: The insertion of the dental implant was done with a surgical motor at an Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation
insertion torque of 25 Ncm and then continued manually to finish the implant placement. The final insertion torque was registered in the patient's record. •152-153: If available, I suggest showing a photograph of applying the PRGF on the denuded implant surface, or a photograph of the grafted site prior to flap closure. Authors: done •170-172: Why a provisional prosthesis was delivered after approximately 5months of healing instead of a definitive? How long was the implant follow-up to determine successful osseointegration? Authors: Before the placement of the definitive prosthesis, we deliver provisional prosthesis so changes, if necessary, could be made and also to permit soft tissue to settle and stabilize around the implants. When the both clinician and patient are satisfied with the results the definitive prosthesis is then delivered. Furthermore, as extra-short implants are placed we perform progressive loading protocol by the use of provisional prosthesis. The following phrase is added to the materials and methods section " As extra-short implants were placed, progressive loading protocol was performed with screw-retained acrylic resin provisional prosthesis". In this study, osteointegration was evaluated at the time of second surgery when transepithelial abutments were connected. Discussion: •180: Please remove ‘’a’’. Authors: done •188-190: Again this is a very interesting technique and it would be beneficial to include at least one photograph to demonstrate that in the ‘’results’’ section. Authors: done Conclusions: •I suggest stating that the conclusions are made within the limitations of this study. •Authors: done Figures •Figure 1: This figure is very interesting but the quality of the upper right graphic makes it hard to read. Consider separating it into 1a and 1b and providing a figure of higher quality that can be easily read. Authors: done •Figures 3,6. More information should be given on how the readers should read the boxplots; not all readers may be familiar with this graphic presentation of the results. Please explain how to identify the median and what percentiles (Q1, Q3) are described by the edges of the boxplots. Authors we added in the figure's legend information that will help in reading the graphs. "The lower and upper border of the box corresponds to the first and third quartiles, and the line inside the box is the median. The ends of the whiskers represent the lowest value within 1.5 interquartil range of the lower quartile, and the highest value within 1.5 interquartil range of the upper quartile".
The statistical analysis section needs to be carefully revised and if revisions affect results of this study the changes should be reported and discussed accordingly. - The statistical analysis has been revised. The following corrections have been done to the statistical analysis in the materials and methods section: "Normality test (Shapiro-Wilk) was applied to verify if data followed a normal distribution. Paired tstudent test...". The differences were statistically significant between measurements before and after surgery. There are also several oversights in the submitted manuscript and I suggest revising carefully before re-submitting.
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- The paper have been revised and errors are now corrected.
Reviewer #2: All in all, I thought this study was a good approach to a difficulty that faces many patients and practitioners. - We deeply acknowledge the reviewer careful reading of the manuscript and also for his/her suggestions that will improve the quality and clarity of the manuscript. Perhaps a comparison and contrast to the tenting procedures used for bone augmentation would be helpful. - The following paragraph has been added. " The use of guided bone regeneration with tenting screw/pins/implants to prevent membrane collapse is another clinical procedure for vertical bone augmentation. This procedure has been shown to achieve an increase of 3.5-7.0 mm30 and, thus, could be indicated in cases where higher bone augmentation is required. However, screw exposure has been reported and is a problem that is associated with gingival thickness and the tension in the flap30".
Additional clinical photographs would be a benefit. - New clinical figures have been now provided (Figures 4, 5 and 7). In addition: On line 22 I think the term extra short implants should be added to the list of key words - Done. Line 47 has a subjective description of augmentation surgery. Perhaps "available solution is to correct the deficiency with a bone augmentation procedure. -Done Line 54 anorganic? Substitute inorganic for anorganic -anorganic is the correct term to describe absence of organic component. Lines 56-60 describe a fibrous connection rather than integration with bone. Have you performed any objective test, I.e. ISQ, to validate the vertical bone growth you have claimed is integrated with bone and not a fibrous connection as cited in your references 13 and 17. - The clinical observation at the time of second surgery indicated the formation of new bone (Fig. 5) however, the type of interface between the implant and the augmented bone is not examined in this study. For this reason we stated in the discusion the need for additional study to verify the concept presented in this paper where biopsies could be harvested for histological analysis.
Line 64 should have a period after platelet rich plasma. A new sentence describing the autografted fibrin membrane should be placed. - Done Line 82 describes pre operative administration of 1g of acetaminophen. What is the purpose of the acetaminophen? - It is prescribed to minimize the pain that patient could suffer after the surgical intervention. Preoperative administration of acetaminophen has been reported to improve the efficacy of local anesthesia in inflamed tissue. Line 83 discusses anesthetizing the patient. What local anesthetic was used, and was in infiltrated or a block injection? Why? - As all surgeries were performed in the mandible both block and infiltration anesthesia were performed. The following phrase has been added "After anesthetizing the surgical site by inferior alveolar nerve block anesthesia and buccal infiltration anesthesia using Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation
articaine hydrochloride with epinephrine (1:100,000)". Line 91 uses the word reallized. Confusing use of the word in the context given. The vertical bone augmentation, if I am correctly interpreting your technique, is an autologous fibrin membrane with bone harvested from the osteotomy. I would suggest substituting " of the extra-short implant, and autologous bone and fibrin graft was used to cover the" - Done. After the surgical description, can you include precautions or special care given to the surgical area? - Patients were instructed to perform light and gentle brushing of the tooth/structures close to the surgical area after 24 h and to avoid chewing on the operated site. Line 105 the word realized was used when performed may be a better verb. - Done. Line 117 I believe the word wet I would be better than humidify - Done. Line 120 the word clinical evolution is not clear. - "Clinical evaluation" is now provided. Line 124 measurements should be singular based upon the objects in the sentence. "Measurement of the distance between the implant shoulder and the bone crest was" would be a better choice. - Done. Line 146 please substitute mandibular for inferior. - Done. Line 157 uses acetaminophen acid, when typically acid is not written - "Acid" is now deleted. Line 158. Sensorial disturbances might be replaced by paresthesia - Done. Line 201 replace suffers with " This study was limited due to the..." - Done. Line 209 extreme jawbone could be replaced with mandibular alveolar ridge. In addiction avoided could be replaced with provided an alternative to more invasive surgical (following on line 210) - Done. Line 308. Change after 5months of to "at 5 months after surgery" - Done. Figures 2,3 and 6 could easily be replaced by a table of each of the 8 subjects, with the variables listed. Too much paper wated on bar graphs with limited information. - As also asked by the first reviewer, we added in the figure's legend information that will help in reading the graphs. "The lower and upper border of the box corresponds to the first and third quartiles, and the line inside the box is the median. The ends of the whiskers represents the lowest value within 1.5 interquartil range of the lower quartile, and the highest value within 1.5 interquartil range of the upper quartile".
Reviewer #3: Please present photographs of the immediate postoperative radiographs after the respective grafting. Please submit photographs of radiographs of the mature turned over bone.
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- We normally do not take radiographs immediately after the insertion of the implant. In the new figures, radiographs at second surgery are now provided. Describe your flap procedure, such as was the flap released. Please describe the type of suture. - The following phrases have been added. "A crestal incision was practiced to elevate a full thickness flap and expose the surgical site". - "suturing (interrupted suture) with monofilament 5/0 nylon suture". This manuscript is of questionable value because the results are not significant and the basic concepts are far from new! Line #117 needs correction. CHANGE HUMIDIFY TO WET AND INJECT SURFACES BETWEEN IMPLANTS AND BEFORE. - Done
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Cover Letter Click here to download Cover Letter: Cover letter-Reviewers.docx
*Article File
1
Implant-guided vertical bone augmentation around extra-short implants for the
2
management of severe bone atrophy
3 4
Anitua E1,2 MD, DDS, PhD, Murias-Freijo A1 DDS, MPhil, Alkhraist MH2 DDS, PhD,
5
Orive G2 PhD.
6 7 8
1
Private practice in oral implantology, c/ Jose Maria Cagigal 19, 01007 Vitoria, Spain
2
BTI Biotechnology Institute, c/ Jacinto Quincoces 39, 01007, Vitoria, Spain.
9 10
MHA acknowledges the support from the Program of Torres Quevedo, Ministry of
11
Economy and Competitivity, co-founded by the European Social Fund (PTQ-11-
12
04711).
13 14
Short title: Implant-guided bone augmentation
15 16 17 18
Correspondence address: Dr. Eduardo Anitua, Eduardo Anitua Foundation; C/ Jose
19
Maria Cagigal 19, 01007 Vitoria, Spain; Phone: +34 945160653, e-mail:
20
[email protected]
21 22
1
23
Abstract
24
The purpose of this study is to describe the conservative treatment of severe vertical
25
bone atrophy by combining the insertion of extra-short implants and implant-guided
26
bone augmentation.
27
For that, low-speed drilling protocol was selected to facilitate the collection of bone
28
particles and to maintain graft osteogenic properties. Extra-short implants were
29
incompletely inserted due to the severe atrophy and the denuded implant surface was
30
covered by autologous bone particles held together by the adhesive properties of plasma
31
rich in growth factors. The surgical site was then covered with resorbable fibrin
32
membrane and the flap was repositioned and sutured.
33
Eight patients with a mean residual bone height of 4.19 ± 0.97 mm were treated
34
according to the described treatment protocol. The distance between the implant
35
shoulder and the bony crest was 1.77 ± 0.18, 2.16 ± 0.23, and 1.97 ± 0.26 mm at mesial,
36
central and distal, respectively. Vertical bone augmentation resulted in the coverage of
37
the 85% of exposed surface by stimulating 1.6 ± 0.5 mm of supra-alveolar bone growth.
38
All placed Extra-short implants were successfully osteointegrated (10/10). After 5 ± 1.6
39
months, provisional screw-retained prostheses were placed.
40
Within the limitations of this study, we conclude that the minimally invasive approach
41
described in this study may successfully rehabilitate extreme vertical bone atrophy in
42
the posterior mandible.
43 44
Key words: vertical bone augmentation, bone atrophy, autologous bone, low-speed
45
drilling, short implants, extra-short implants.
2
46 47
Introduction
48
Oral rehabilitation of severely resorbed edentulous ridges is a challenging problem due
49
to reduced residual height and usually requires the performance of advanced bone
50
augmentation such as the use of bone blocks harvested from extra-or intr-oral donor
51
sites. Such surgical treatment is associated with significant risk of morbidity and
52
increases the cost and time necessary for providing implant-supported prosthesis1. For
53
that, clinicians are seeking minimally invasive alternatives that permit the completion of
54
implant therapy at lesser surgical morbidity, in a shorter time and at lower cost1,2. This
55
resulted in the design of reduced-length implants that lower the volume of bone
56
necessary to support the implant fixture and, thus, limit the need for advanced bone
57
augmentation surgery 1.
58
Although initially the use of short implants was associated with higher risk of failure3,
59
recent studies have proven that short implants are as successful as standard implants
60
even after long periods of function4-7. This could be the result of optimized clinical
61
protocols and improved implant design that help to overcome the consequences of
62
unfavorable crown to implant ratio and off-axis loading1,8. Extra-short implants (length
63
≤ 6.5 mm) are indicated when residual bone height is less than 7 mm and several studies
64
are now available on their efficiency in the treatment of severely atrophied residual
65
ridges. Anitua et al. (2013) reported a survival rate of 98.2% for 114 extra-short
66
implants with a mean follow-up time of 26 months since loading1. In another study, 6.3
67
mm-long implants showed an average peri-implant bone loss of 1.24 mm that is
68
comparable to standard implants placed after vertical bone augmentation2.
3
69
However, clinicians may face challenging situations where the residual bone height is
70
insufficient to support even extra-short implants. In such extreme situation, available
71
solution is to correct the deficiency with a bone augmentation surgery. This has
72
encouraged us to develop a clinical technique to obtain vertical bone growth around
73
extra-short implants and make feasible the option of conservative rehabilitation of
74
severely resorbed mandible with implant-supported prosthesis.
75
Supralveolar bone formation around dental implants was first reported by Simion et al.
76
(1994)9 and then corroborated by Jovanovic et al. (1995)10. The technique resulted in
77
the gain of 3-4 mm of vertical bone growth. Studies on the type of grafting material
78
showed that the adjuvant use of autologous bone, DFDBA and anorganic bovine bone
79
improved the outcome of vertical bone augmentation and enhanced the predictability of
80
the technique11-16.
81
Several studies have observed better postoperative recovery (less inflammation and
82
pain) in surgeries were autologous plasma rich in growth factors (PRGF) was
83
employed17,18. PRGF use in endodontic surgery significantly improved patients' quality
84
of life, the functional activities were less impaired and pain was significantly lower
85
during the first 6 days after surgery19. During bone augmentation surgery, the coverage
86
of the titanium mesh with fibrin membrane showed efficiency in preventing mesh
87
exposure and thus minimizing the risk of failure due to graft infection20.
88
In the present study, the sole use of PRGF clot as grafting material was efficient to
89
promote new bone formation after sinus floor augmentation. The statistical analysis
90
showed similar bone gain when PRGF was used with/without bone graft (autologous
91
bone, anorganic bovine bone or combination of the two).
92
In this study we describe implant-guided bone augmentation around extra-short 4
93
implants for the treatment of posterior mandiblular sites with severe resorption. The
94
grafting material was autologous bone particles harvested from the drilling procedure
95
and stored in autologous platelet rich plasma. A resorbable fibrin membrane was used to
96
cover the surgical site. Thus, this study aims to evaluate surgical complications that may
97
occur after the performance of the described technique and also evaluate the amount of
98
vertical bone augmentation that is achieved around the dental implants.
99
Materials and methods
100
Patients data base from a private clinic was analyzed retrospectively to identify patients
101
with severe jaw atrophy defined as the presence of a residual height < 7 mm. Patients
102
enrollment in the study was based on meeting the following criteria: Residual height
103
less than 7 mm, incomplete insertion of the extra-short implants indicated by the
104
presence of a vertical gap between the bone crest and the implant shoulder, and
105
performance of implant-guided vertical bone growth. Patients who failed to meet any of
106
these criteria were excluded from the study. The principal outcomes were the bone
107
coverage of the denuded implant surface and dental implant osseointegration.
108
Preoperatively, residual bone height was retrieved by the analysis of a cone-beam CT
109
scan (GALILEOS 3D scanner and BTI scan) and the treatment plan was set to include
110
the provision of implant-supported prosthesis, the insertion of at least one extra-short
111
implant and the performance of implant-guided bone augmentation. After the discussion
112
of treatment plan with the patients, they agreed to give their informed consent.
113
Surgical procedure
114
Patients received 1 g of amoxicillin (600 mg of clindamycin for allergic patients) 30
115
minutes and 1 g of acetaminophen 60 minutes before surgery. Local anesthesia was
5
116
achieved by inferior alveolar nerve block anesthesia and buccal infiltration anesthesia
117
using articaine hydrochloride with epinephrine (1:100,000). A crestal incision was
118
practiced to elevate a full thickness flap and expose the surgical site. Implant site
119
preparation was realized following a biological low-speed (150 rpm) drilling without
120
irrigation1,21. The bone type, determined according to Lekohlm and Zarb classification,
121
was used to select the sequence of bone drills and the final drill diameter as described
122
elsewhere1.
123
The drilling procedure of the residual bone was divided in two phases: the first phase
124
uses conventional drills and the working length was set 1 mm shorter than the height of
125
the residual alveolar bone (in all cases the residual bone height was shorter than the
126
length of the implant). The second phase uses a special drill with frontal cutting surface
127
to prepare the last 1 mm of the implant site. The insertion of the dental implant was
128
done with a surgical motor at an insertion torque of 25 Ncm and then continued
129
manually to finish the implant placement. The final insertion torque was registered in
130
the patient's record.
131
The severe bone atrophy did not permit the complete insertion of the extra-short implant
132
and a periodontal probe was used to measure the distance from the implant shoulder and
133
the crest of alveolar bone at mesial, central and distal aspects. The distance between the
134
implant shoulder and the crest of the alveolar bone was 1.77 ± 0.18, 2.16 ± 0.23, and
135
1.97 ± 0.26 mm at mesial, central and distal (range: 1.1-2.6 mm at mesial, 1.2-2.9 mm at
136
central and 1.1-3.1 mm at distal).
137 138
For that, autologous bone and fibrin graft was used to cover the exposed implant’s
139
threads (Figure 1). The low-speed drilling and the design of the bone drills permitted the 6
140
collection of bone particles during the preparation of implant site. The harvested
141
autologous bone was stored in the fraction 2 of the PRGF-Endoret (BTI; Vitoria, Spain)
142
until use. This resulted in the formation of a fibrin clot that glued together the
143
autologous graft particles (Figure 1). To stimulate supralveolar bone augmentation,
144
fibrin-glued bone graft was applied on the denuded implant surface (Figure 1). Fibrin
145
membrane, prepared from F1 of PRGF, was compressed to provide thin and consistent
146
membrane that was then applied to cover the surgical site (Figure 1) before flap
147
reposition and suturing (interrupted suture) with monofilament 5/0 nylon suture.
148
Postoperatively, patients were instructed to perform light and gentle brushing of the
149
tooth/structures close to the surgical area after 24 h and to avoid chewing on the
150
operated site.
151
After at least 4 months, a second surgery was then performed to connect transepithelial
152
abutments (Multi-Im, BTI, Vitoria, Spain). The residual distance between the implant
153
shoulder and the bone crest was measured again. As extra-short implants were placed,
154
progressive loading protocol was performed with screw-retained acrylic resin
155
provisional prosthesis.
156
Plasma rich in growth factors preparation
157
Plasma rich in growth factors was prepared using Endoret Kit (BTI, Vitoria, Spain).
158
Briefly, citrated venous blood was centrifuged at 460 g for 8 minutes to separate blood
159
components according to the gravity density. Then, plasma column was fractioned into
160
fraction 2 (F2) defined as the 2 mm of plasma above the buffy coat and fraction 1 (F1)
161
defined as the plasma column above the F2.
162
Activated fraction 1 (F1) was employed to prepare a fibrin membrane that covered the
163
surgical area before flap closure and activated fraction 2 (F2) was used to store bone 7
164
particulate harvested during the drilling procedure, to wet and inject surfaces between
165
implants and before insertion.
166
Postoperative phase:
167
Follow-up visits were scheduled to remove sutures and to detect any surgical
168
complications. Clinical evaluation and implants status were also monitored. It is
169
important to mention that during the period of implant osteointegration no provisional
170
prosthesis was delivered to avoid mobilization of the graft.
171
Data collection and statistical analysis
172
Measurement of the distance between the implant shoulder and the bone crest was
173
realized by the same clinician (MFA). Normality test (Shapiro-Wilk) was applied to
174
verify if data followed a normal distribution. Paired t-student test was applied to analyze
175
the statistical significant of the difference between both measurements. The level of
176
statistical significance was set at p
AAID-JOI-D-13-00131R1
Full Title:
Implant-guided vertical bone augmentation around extra-short implants for the management of severe bone atrophy
Short Title:
Implant-guided bone augmentation
Article Type:
Clinical Research
Keywords:
vertical bone augmentation, bone atrophy, autologous bone, low-speed drilling, short implants, extra-short implants
Corresponding Author:
GORKA ORIVE, Pharmacy University of the Basque Country Vitoria, ALAVA SPAIN
Corresponding Author Secondary Information: Corresponding Author's Institution:
University of the Basque Country
Corresponding Author's Secondary Institution: First Author:
Eduardo Anitua
First Author Secondary Information: Order of Authors:
Eduardo Anitua Alia Murias-Freijo Mohammad Alkhraist GORKA ORIVE, Pharmacy
Order of Authors Secondary Information: Abstract:
The purpose of this study is to describe the conservative treatment of severe vertical bone atrophy by combining the insertion of extra-short implants and implant-guided bone augmentation. For that, low-speed drilling protocol was selected to facilitate the collection of bone particles and to maintain graft osteogenic properties. Extra-short implants were incompletely inserted due to the severe atrophy and the denuded implant surface was covered by autologous bone particles held together by the adhesive properties of plasma rich in growth factors. The surgical site was then covered with resorbable fibrin membrane and the flap was repositioned and sutured. Eight patients with a mean residual bone height of 4.19 ± 0.97 mm were treated according to the described treatment protocol. The distance between the implant shoulder and the bony crest was 1.77 ± 0.18, 2.16 ± 0.23, and 1.97 ± 0.26 mm at mesial, central and distal, respectively. Vertical bone augmentation resulted in the coverage of the 85% of exposed surface by stimulating 1.6 ± 0.5 mm of supra-alveolar bone growth. All placed Extra-short implants were successfully osteointegrated (10/10). After 5 ± 1.6 months, provisional screw-retained prostheses were placed. Within the limitations of this study, we conclude that the minimally invasive approach described in this study may successfully rehabilitate extreme vertical bone atrophy in the posterior mandible.
Response to Reviewers:
Editor-in-Chief Journal of Oral Implantology Dear Dr. James Rutkowski, DMD, PhD We deeply acknowledge the reviewers for the careful and detailed reading of the
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manuscript and also evaluate the comments and questions formulated to improve our manuscript. We have addressed every comment that the reviewers have made and hope to answer adequately their inquiries. Below, we detail our answers to the reviewers and inform that all changes have been marked within the manuscript. Kind regards, [removed for blinding purposes] Reviewers' comments: Reviewer #1: Dear author(s), I found the submitted manuscript to be of interest and relevance to the scope of the JOI. It describes and interesting technique for the rehabilitation of the atrophic posterior mandible. - We are thankful for the detailed analysis of the manuscript and the careful reading of the manuscript. The reviewer notes were very helpful to improve the manuscript. However, I have identified several areas that need to be clarified before the manuscript is appropriate for publication. The major areas of concern are underlined in the suggestions listed in the attached document. - All the listed suggestions have addressed adequately and changes have been done accordingly. Title: •Please consider using ‘’augmentation’’ instead of ‘’growth’’ as a more appropriate term Authors: Done Short title: •same in lieu of ‘’formation’’. Authors: Done Abstract: •Please change the sentence to :’’Eight patients with a mean residual bone height of 4.19 ± 0.97 mm’’ Authors: Done •You can add the word ‘’, respectively’’ at the end of the sentence: ‘’The distance between the implant shoulder and the bony crest was 1.77 ± 0.18, 2.16 ± 0.23, and 1.97 ± 0.26 mm at mesial, central and distal…’’ for ease of understanding by the reader. Authors: Done •‘’ by stimulating about 2 mm of supra-alveolar bone growth’’, Consider providing the specific mean of vertical bone augmentation followed by the standard deviation estimated instead of simply reporting the rounded number ‘’2mm’ Authors: The exact value is now provided "1.6 ± 0.5 mm of supra-alveolar bone growth" •‘’Extra-short implants were successfully osteointegrated and gave support to provisional screw-retained prostheses.’’: You may want to consider reporting your results more distinctly. It should be stated that all placed implants successfully osseointegrated; consider adding the proportion of placed to osseointegrated implants (10/10). Also mention when the provisional restorations were placed. Authors: Done •Please add that your conclusion is stated ‘’within the limitations of this study’’. Also consider changing ‘’paper’’ to ‘’study’’ or another term that can be used for scientific papers. Authors: Done Introduction: • 25: A single edentulous site may be severely resorbed and still the technique reported would be applicable. I feel that it will be more accurate to change ‘’jaw’’ to Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation
‘’edentulous ridges’’, or another similar term. Authors: Done •26-27: Autologous bone blocks are one of many alternatives for vertical bone augmentation. You can either reference additional alternatives to provide the reader with a better understanding of the currently used techniques for vertical bone augmentation, or rephrase to explain that this is only one of many options. Authors: Done •32: Please change ‘’encompass’’ to a more appropriate term. Authors: Done •34: Please change ‘’the first’’ with ‘’initially’’ Authors: Done •35:’’proven’’ •36:Please change to: ‘’even after long periods of function’’ Authors: Done •38: ‘’ratio’’ Authors: Done •40: re-consider the use of ‘’jaw’’ Authors: Done •40: Citations with authors name in text should come with date indicated in parenthesis. Please add the year of the publication for ease of reference. E.g. Anitua et al. (2013) Authors: Done •42:’’another’’ instead of ‘’other’’ Authors: Done •42-44: How long was the follow-up? ‘‘Long’’ can be changed to ‘’conventional’’ or ‘’standard’’. Please specify if ‘’6.3mm’’ refers to their length. Authors: Done •48: How did you specify the number ‘’2-3mm’’. Do you exclude less than 2mm? Authors: the phrase have been removed. •49: Please delete ‘’it’’ Authors: Done •53: ‘’filling’’ can be changed to a more appropriate term. Authors: Done •55:’’enhanced’’ Authors: Done •60: by ‘’covered’’ you mean on the outside, or do you mean separated? Authors:" was covered on the outside by a thick layer of connective tissue29". •56-60: These findings, although important to report, are not studied in your investigation. Thus, it would be more appropriate to consider moving them to the discussions section. Authors: Done •62:Please change to : ‘’posterior mandibular sites’’ Authors: Done •62: See previous comment. ‘‘Filling material’’ is not a scientifically valid term for bone grafts used for vertical bone augmentation and changing it to a more relevant term would be of benefit. Authors: "grafting material" is now provided •64. Consider changing ‘’,’’ to a full stop and starting a new sentence to describe the fibrin membrane you used for coverage. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation
Authors: done •The introduction is lacking report of specific aims for this study. I suggest you distinctly report the aims of the study in the last paragraph of the introduction. Authors: "Thus, this study aims to evaluate surgical complications that may occur after the performance of the described technique and also evaluate the amount of vertical bone augmentation that is achieved around the dental implants". M&M •67. ‘’Patients data base’’ Is this database coming from a private clinic, multiple clinics? A hospital setting? Authors: "Patients data base from a private clinic". •84: Please provide a reference for ‘’biological’’ low-speed drilling. Authors: done •87: You state that ‘’The drilling procedure was divided in two phases: the first phase uses conventional drills and the working length was set 1 mm shorter than the total length of the implant bed ‘’ and then you report that the distance from the crest to the implant shoulder is ~2mm depending on the surface. I did not understand how the distance is approximately 2mm if you drilled only 1mm shorter of the total length. Did you mean 1mm shorter of the already reduced implant length? Authors: - The first sentence refer to the drilling procedure that is done before the insertion of the dental implant. For example if we have residual bone height of 4 mm, then the working length of conventional drill is 3 mm and the last 1 mm is drilled with frontal cutting drill. - The second sentence refer to the part of implant surface that is exposed after implant insertion in the bone. For example if 5.5 mm-long implant is placed in residual bone height of 4 mm then 1.5 mm of implant will be exposed (distance between implant shoulder and bone crest) •99: PRGF seems to be an important aspect of your suggested treatment, but is first reported here. I suggest adding some data in regards to the benefits of using PRGF in this case and for justification of its use in the introduction section. A photograph of the autologous particles in the fibrin mesh would be of great interest. Authors: done •120: correct ‘’evolution’’ Authors: "Clinical evaluation". •125-126: Appropriate statistical analysis is very important to validate the accuracy of your results. You have stated that: ‘’t-student test was applied to analyze the statistical significant of the difference between both measurements. ‘’ In the literature, the term ‘’t-test’’, or ‘’student’s t-test’’ is used to describe an ‘’unpaired t-test’’. In your case you have compared numerical data pre-operatively and postoperatively in the same patients. Therefore a ‘’paired t-test’’ is the appropriate statistical test, based on the hypothesis that your data come from a normally distributed pool. I suggest that, if you have already used a ‘’paired t-test’’ you explicitly mention that. Otherwise, I recommend performing the analysis using an‘’unpaired t-test’’. I also encourage you to report the P-value obtained for each comparison in the results section to distinctly show that your results are statistically significant. Authors: the following corrections have been done to the statistical analysis in the materials and methods section: "Normality test (Shapiro-Wilk) was applied to verify if data followed a normal distribution. Paired t-student test...". The differences were statistically significant between measurements before and after surgery. Results •132: Consider using ‘’fulfilled’’ instead of ‘’completed’’. Authors: done •133: Add ‘’to’’ following ‘’due’’ Authors: done •139: In scientific texts, use the correct terms, if available. I suggest using the term “Cone beam computed tomography’’, or ‘’cone beam volumetric tomogram’’. Authors: done •143: The insertion torque is a finding of interest. Please add information on how you evaluated that in the materials and methods section. Authors: The following phrases have been added to the materials and methods section: The insertion of the dental implant was done with a surgical motor at an Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation
insertion torque of 25 Ncm and then continued manually to finish the implant placement. The final insertion torque was registered in the patient's record. •152-153: If available, I suggest showing a photograph of applying the PRGF on the denuded implant surface, or a photograph of the grafted site prior to flap closure. Authors: done •170-172: Why a provisional prosthesis was delivered after approximately 5months of healing instead of a definitive? How long was the implant follow-up to determine successful osseointegration? Authors: Before the placement of the definitive prosthesis, we deliver provisional prosthesis so changes, if necessary, could be made and also to permit soft tissue to settle and stabilize around the implants. When the both clinician and patient are satisfied with the results the definitive prosthesis is then delivered. Furthermore, as extra-short implants are placed we perform progressive loading protocol by the use of provisional prosthesis. The following phrase is added to the materials and methods section " As extra-short implants were placed, progressive loading protocol was performed with screw-retained acrylic resin provisional prosthesis". In this study, osteointegration was evaluated at the time of second surgery when transepithelial abutments were connected. Discussion: •180: Please remove ‘’a’’. Authors: done •188-190: Again this is a very interesting technique and it would be beneficial to include at least one photograph to demonstrate that in the ‘’results’’ section. Authors: done Conclusions: •I suggest stating that the conclusions are made within the limitations of this study. •Authors: done Figures •Figure 1: This figure is very interesting but the quality of the upper right graphic makes it hard to read. Consider separating it into 1a and 1b and providing a figure of higher quality that can be easily read. Authors: done •Figures 3,6. More information should be given on how the readers should read the boxplots; not all readers may be familiar with this graphic presentation of the results. Please explain how to identify the median and what percentiles (Q1, Q3) are described by the edges of the boxplots. Authors we added in the figure's legend information that will help in reading the graphs. "The lower and upper border of the box corresponds to the first and third quartiles, and the line inside the box is the median. The ends of the whiskers represent the lowest value within 1.5 interquartil range of the lower quartile, and the highest value within 1.5 interquartil range of the upper quartile".
The statistical analysis section needs to be carefully revised and if revisions affect results of this study the changes should be reported and discussed accordingly. - The statistical analysis has been revised. The following corrections have been done to the statistical analysis in the materials and methods section: "Normality test (Shapiro-Wilk) was applied to verify if data followed a normal distribution. Paired tstudent test...". The differences were statistically significant between measurements before and after surgery. There are also several oversights in the submitted manuscript and I suggest revising carefully before re-submitting.
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- The paper have been revised and errors are now corrected.
Reviewer #2: All in all, I thought this study was a good approach to a difficulty that faces many patients and practitioners. - We deeply acknowledge the reviewer careful reading of the manuscript and also for his/her suggestions that will improve the quality and clarity of the manuscript. Perhaps a comparison and contrast to the tenting procedures used for bone augmentation would be helpful. - The following paragraph has been added. " The use of guided bone regeneration with tenting screw/pins/implants to prevent membrane collapse is another clinical procedure for vertical bone augmentation. This procedure has been shown to achieve an increase of 3.5-7.0 mm30 and, thus, could be indicated in cases where higher bone augmentation is required. However, screw exposure has been reported and is a problem that is associated with gingival thickness and the tension in the flap30".
Additional clinical photographs would be a benefit. - New clinical figures have been now provided (Figures 4, 5 and 7). In addition: On line 22 I think the term extra short implants should be added to the list of key words - Done. Line 47 has a subjective description of augmentation surgery. Perhaps "available solution is to correct the deficiency with a bone augmentation procedure. -Done Line 54 anorganic? Substitute inorganic for anorganic -anorganic is the correct term to describe absence of organic component. Lines 56-60 describe a fibrous connection rather than integration with bone. Have you performed any objective test, I.e. ISQ, to validate the vertical bone growth you have claimed is integrated with bone and not a fibrous connection as cited in your references 13 and 17. - The clinical observation at the time of second surgery indicated the formation of new bone (Fig. 5) however, the type of interface between the implant and the augmented bone is not examined in this study. For this reason we stated in the discusion the need for additional study to verify the concept presented in this paper where biopsies could be harvested for histological analysis.
Line 64 should have a period after platelet rich plasma. A new sentence describing the autografted fibrin membrane should be placed. - Done Line 82 describes pre operative administration of 1g of acetaminophen. What is the purpose of the acetaminophen? - It is prescribed to minimize the pain that patient could suffer after the surgical intervention. Preoperative administration of acetaminophen has been reported to improve the efficacy of local anesthesia in inflamed tissue. Line 83 discusses anesthetizing the patient. What local anesthetic was used, and was in infiltrated or a block injection? Why? - As all surgeries were performed in the mandible both block and infiltration anesthesia were performed. The following phrase has been added "After anesthetizing the surgical site by inferior alveolar nerve block anesthesia and buccal infiltration anesthesia using Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation
articaine hydrochloride with epinephrine (1:100,000)". Line 91 uses the word reallized. Confusing use of the word in the context given. The vertical bone augmentation, if I am correctly interpreting your technique, is an autologous fibrin membrane with bone harvested from the osteotomy. I would suggest substituting " of the extra-short implant, and autologous bone and fibrin graft was used to cover the" - Done. After the surgical description, can you include precautions or special care given to the surgical area? - Patients were instructed to perform light and gentle brushing of the tooth/structures close to the surgical area after 24 h and to avoid chewing on the operated site. Line 105 the word realized was used when performed may be a better verb. - Done. Line 117 I believe the word wet I would be better than humidify - Done. Line 120 the word clinical evolution is not clear. - "Clinical evaluation" is now provided. Line 124 measurements should be singular based upon the objects in the sentence. "Measurement of the distance between the implant shoulder and the bone crest was" would be a better choice. - Done. Line 146 please substitute mandibular for inferior. - Done. Line 157 uses acetaminophen acid, when typically acid is not written - "Acid" is now deleted. Line 158. Sensorial disturbances might be replaced by paresthesia - Done. Line 201 replace suffers with " This study was limited due to the..." - Done. Line 209 extreme jawbone could be replaced with mandibular alveolar ridge. In addiction avoided could be replaced with provided an alternative to more invasive surgical (following on line 210) - Done. Line 308. Change after 5months of to "at 5 months after surgery" - Done. Figures 2,3 and 6 could easily be replaced by a table of each of the 8 subjects, with the variables listed. Too much paper wated on bar graphs with limited information. - As also asked by the first reviewer, we added in the figure's legend information that will help in reading the graphs. "The lower and upper border of the box corresponds to the first and third quartiles, and the line inside the box is the median. The ends of the whiskers represents the lowest value within 1.5 interquartil range of the lower quartile, and the highest value within 1.5 interquartil range of the upper quartile".
Reviewer #3: Please present photographs of the immediate postoperative radiographs after the respective grafting. Please submit photographs of radiographs of the mature turned over bone.
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- We normally do not take radiographs immediately after the insertion of the implant. In the new figures, radiographs at second surgery are now provided. Describe your flap procedure, such as was the flap released. Please describe the type of suture. - The following phrases have been added. "A crestal incision was practiced to elevate a full thickness flap and expose the surgical site". - "suturing (interrupted suture) with monofilament 5/0 nylon suture". This manuscript is of questionable value because the results are not significant and the basic concepts are far from new! Line #117 needs correction. CHANGE HUMIDIFY TO WET AND INJECT SURFACES BETWEEN IMPLANTS AND BEFORE. - Done
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Cover Letter Click here to download Cover Letter: Cover letter-Reviewers.docx
*Article File
1
Implant-guided vertical bone augmentation around extra-short implants for the
2
management of severe bone atrophy
3 4
Anitua E1,2 MD, DDS, PhD, Murias-Freijo A1 DDS, MPhil, Alkhraist MH2 DDS, PhD,
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Orive G2 PhD.
6 7 8
1
Private practice in oral implantology, c/ Jose Maria Cagigal 19, 01007 Vitoria, Spain
2
BTI Biotechnology Institute, c/ Jacinto Quincoces 39, 01007, Vitoria, Spain.
9 10
MHA acknowledges the support from the Program of Torres Quevedo, Ministry of
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Economy and Competitivity, co-founded by the European Social Fund (PTQ-11-
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04711).
13 14
Short title: Implant-guided bone augmentation
15 16 17 18
Correspondence address: Dr. Eduardo Anitua, Eduardo Anitua Foundation; C/ Jose
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Maria Cagigal 19, 01007 Vitoria, Spain; Phone: +34 945160653, e-mail:
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[email protected]
21 22
1
23
Abstract
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The purpose of this study is to describe the conservative treatment of severe vertical
25
bone atrophy by combining the insertion of extra-short implants and implant-guided
26
bone augmentation.
27
For that, low-speed drilling protocol was selected to facilitate the collection of bone
28
particles and to maintain graft osteogenic properties. Extra-short implants were
29
incompletely inserted due to the severe atrophy and the denuded implant surface was
30
covered by autologous bone particles held together by the adhesive properties of plasma
31
rich in growth factors. The surgical site was then covered with resorbable fibrin
32
membrane and the flap was repositioned and sutured.
33
Eight patients with a mean residual bone height of 4.19 ± 0.97 mm were treated
34
according to the described treatment protocol. The distance between the implant
35
shoulder and the bony crest was 1.77 ± 0.18, 2.16 ± 0.23, and 1.97 ± 0.26 mm at mesial,
36
central and distal, respectively. Vertical bone augmentation resulted in the coverage of
37
the 85% of exposed surface by stimulating 1.6 ± 0.5 mm of supra-alveolar bone growth.
38
All placed Extra-short implants were successfully osteointegrated (10/10). After 5 ± 1.6
39
months, provisional screw-retained prostheses were placed.
40
Within the limitations of this study, we conclude that the minimally invasive approach
41
described in this study may successfully rehabilitate extreme vertical bone atrophy in
42
the posterior mandible.
43 44
Key words: vertical bone augmentation, bone atrophy, autologous bone, low-speed
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drilling, short implants, extra-short implants.
2
46 47
Introduction
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Oral rehabilitation of severely resorbed edentulous ridges is a challenging problem due
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to reduced residual height and usually requires the performance of advanced bone
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augmentation such as the use of bone blocks harvested from extra-or intr-oral donor
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sites. Such surgical treatment is associated with significant risk of morbidity and
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increases the cost and time necessary for providing implant-supported prosthesis1. For
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that, clinicians are seeking minimally invasive alternatives that permit the completion of
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implant therapy at lesser surgical morbidity, in a shorter time and at lower cost1,2. This
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resulted in the design of reduced-length implants that lower the volume of bone
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necessary to support the implant fixture and, thus, limit the need for advanced bone
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augmentation surgery 1.
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Although initially the use of short implants was associated with higher risk of failure3,
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recent studies have proven that short implants are as successful as standard implants
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even after long periods of function4-7. This could be the result of optimized clinical
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protocols and improved implant design that help to overcome the consequences of
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unfavorable crown to implant ratio and off-axis loading1,8. Extra-short implants (length
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≤ 6.5 mm) are indicated when residual bone height is less than 7 mm and several studies
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are now available on their efficiency in the treatment of severely atrophied residual
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ridges. Anitua et al. (2013) reported a survival rate of 98.2% for 114 extra-short
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implants with a mean follow-up time of 26 months since loading1. In another study, 6.3
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mm-long implants showed an average peri-implant bone loss of 1.24 mm that is
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comparable to standard implants placed after vertical bone augmentation2.
3
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However, clinicians may face challenging situations where the residual bone height is
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insufficient to support even extra-short implants. In such extreme situation, available
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solution is to correct the deficiency with a bone augmentation surgery. This has
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encouraged us to develop a clinical technique to obtain vertical bone growth around
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extra-short implants and make feasible the option of conservative rehabilitation of
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severely resorbed mandible with implant-supported prosthesis.
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Supralveolar bone formation around dental implants was first reported by Simion et al.
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(1994)9 and then corroborated by Jovanovic et al. (1995)10. The technique resulted in
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the gain of 3-4 mm of vertical bone growth. Studies on the type of grafting material
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showed that the adjuvant use of autologous bone, DFDBA and anorganic bovine bone
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improved the outcome of vertical bone augmentation and enhanced the predictability of
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the technique11-16.
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Several studies have observed better postoperative recovery (less inflammation and
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pain) in surgeries were autologous plasma rich in growth factors (PRGF) was
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employed17,18. PRGF use in endodontic surgery significantly improved patients' quality
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of life, the functional activities were less impaired and pain was significantly lower
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during the first 6 days after surgery19. During bone augmentation surgery, the coverage
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of the titanium mesh with fibrin membrane showed efficiency in preventing mesh
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exposure and thus minimizing the risk of failure due to graft infection20.
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In the present study, the sole use of PRGF clot as grafting material was efficient to
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promote new bone formation after sinus floor augmentation. The statistical analysis
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showed similar bone gain when PRGF was used with/without bone graft (autologous
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bone, anorganic bovine bone or combination of the two).
92
In this study we describe implant-guided bone augmentation around extra-short 4
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implants for the treatment of posterior mandiblular sites with severe resorption. The
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grafting material was autologous bone particles harvested from the drilling procedure
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and stored in autologous platelet rich plasma. A resorbable fibrin membrane was used to
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cover the surgical site. Thus, this study aims to evaluate surgical complications that may
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occur after the performance of the described technique and also evaluate the amount of
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vertical bone augmentation that is achieved around the dental implants.
99
Materials and methods
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Patients data base from a private clinic was analyzed retrospectively to identify patients
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with severe jaw atrophy defined as the presence of a residual height < 7 mm. Patients
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enrollment in the study was based on meeting the following criteria: Residual height
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less than 7 mm, incomplete insertion of the extra-short implants indicated by the
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presence of a vertical gap between the bone crest and the implant shoulder, and
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performance of implant-guided vertical bone growth. Patients who failed to meet any of
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these criteria were excluded from the study. The principal outcomes were the bone
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coverage of the denuded implant surface and dental implant osseointegration.
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Preoperatively, residual bone height was retrieved by the analysis of a cone-beam CT
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scan (GALILEOS 3D scanner and BTI scan) and the treatment plan was set to include
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the provision of implant-supported prosthesis, the insertion of at least one extra-short
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implant and the performance of implant-guided bone augmentation. After the discussion
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of treatment plan with the patients, they agreed to give their informed consent.
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Surgical procedure
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Patients received 1 g of amoxicillin (600 mg of clindamycin for allergic patients) 30
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minutes and 1 g of acetaminophen 60 minutes before surgery. Local anesthesia was
5
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achieved by inferior alveolar nerve block anesthesia and buccal infiltration anesthesia
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using articaine hydrochloride with epinephrine (1:100,000). A crestal incision was
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practiced to elevate a full thickness flap and expose the surgical site. Implant site
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preparation was realized following a biological low-speed (150 rpm) drilling without
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irrigation1,21. The bone type, determined according to Lekohlm and Zarb classification,
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was used to select the sequence of bone drills and the final drill diameter as described
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elsewhere1.
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The drilling procedure of the residual bone was divided in two phases: the first phase
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uses conventional drills and the working length was set 1 mm shorter than the height of
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the residual alveolar bone (in all cases the residual bone height was shorter than the
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length of the implant). The second phase uses a special drill with frontal cutting surface
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to prepare the last 1 mm of the implant site. The insertion of the dental implant was
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done with a surgical motor at an insertion torque of 25 Ncm and then continued
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manually to finish the implant placement. The final insertion torque was registered in
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the patient's record.
131
The severe bone atrophy did not permit the complete insertion of the extra-short implant
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and a periodontal probe was used to measure the distance from the implant shoulder and
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the crest of alveolar bone at mesial, central and distal aspects. The distance between the
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implant shoulder and the crest of the alveolar bone was 1.77 ± 0.18, 2.16 ± 0.23, and
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1.97 ± 0.26 mm at mesial, central and distal (range: 1.1-2.6 mm at mesial, 1.2-2.9 mm at
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central and 1.1-3.1 mm at distal).
137 138
For that, autologous bone and fibrin graft was used to cover the exposed implant’s
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threads (Figure 1). The low-speed drilling and the design of the bone drills permitted the 6
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collection of bone particles during the preparation of implant site. The harvested
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autologous bone was stored in the fraction 2 of the PRGF-Endoret (BTI; Vitoria, Spain)
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until use. This resulted in the formation of a fibrin clot that glued together the
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autologous graft particles (Figure 1). To stimulate supralveolar bone augmentation,
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fibrin-glued bone graft was applied on the denuded implant surface (Figure 1). Fibrin
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membrane, prepared from F1 of PRGF, was compressed to provide thin and consistent
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membrane that was then applied to cover the surgical site (Figure 1) before flap
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reposition and suturing (interrupted suture) with monofilament 5/0 nylon suture.
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Postoperatively, patients were instructed to perform light and gentle brushing of the
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tooth/structures close to the surgical area after 24 h and to avoid chewing on the
150
operated site.
151
After at least 4 months, a second surgery was then performed to connect transepithelial
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abutments (Multi-Im, BTI, Vitoria, Spain). The residual distance between the implant
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shoulder and the bone crest was measured again. As extra-short implants were placed,
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progressive loading protocol was performed with screw-retained acrylic resin
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provisional prosthesis.
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Plasma rich in growth factors preparation
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Plasma rich in growth factors was prepared using Endoret Kit (BTI, Vitoria, Spain).
158
Briefly, citrated venous blood was centrifuged at 460 g for 8 minutes to separate blood
159
components according to the gravity density. Then, plasma column was fractioned into
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fraction 2 (F2) defined as the 2 mm of plasma above the buffy coat and fraction 1 (F1)
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defined as the plasma column above the F2.
162
Activated fraction 1 (F1) was employed to prepare a fibrin membrane that covered the
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surgical area before flap closure and activated fraction 2 (F2) was used to store bone 7
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particulate harvested during the drilling procedure, to wet and inject surfaces between
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implants and before insertion.
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Postoperative phase:
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Follow-up visits were scheduled to remove sutures and to detect any surgical
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complications. Clinical evaluation and implants status were also monitored. It is
169
important to mention that during the period of implant osteointegration no provisional
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prosthesis was delivered to avoid mobilization of the graft.
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Data collection and statistical analysis
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Measurement of the distance between the implant shoulder and the bone crest was
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realized by the same clinician (MFA). Normality test (Shapiro-Wilk) was applied to
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verify if data followed a normal distribution. Paired t-student test was applied to analyze
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the statistical significant of the difference between both measurements. The level of
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statistical significance was set at p
