Abstract
Objective
Narrow alveolar ridges pose a serious challenge for successful placement of endosseous implants and alveolar ridge widening procedure is indicated in cases of crest thickness of ≤4.0 mm. The study evaluated and compared, immediate and delayed techniques of implant placement using split crest technique to augment atrophic narrow alveolar ridges.
Methods
The study was carried out in 10 patients randomly divided into two groups of five each for immediate or delayed placement of implants. Implants were placed simultaneously after split crest procedure in immediate technique and after 3–4 weeks of healing in delayed technique. Data collected was statistically analyzed by SPSS version 22 using unpaired t-test, ANOVA and Pearson's correlation with p value = 0.05.
Results
Statistically significant (p = 0.000) difference was observed for implant stability at intra-op, 4 months and 6 months post-op between the two groups, however there was no statistically significant difference in amount of augmentation achieved between the two groups.
Conclusion
We observed that both the techniques were comparable on the basis of augmentation achieved, implant success and survival rates, whereas implant stability was significantly higher in delayed technique group.
Keywords: Endosseous implants, Alveolar ridge, Split crest technique, Success and survival rates
1. Introduction
Severe alveolar bone resorption can occur after tooth removal. Localized alveolar defects are perplexing considering the orthodox prosthodontic treatment viewpoint and bone augmentation is desirable after alveolar bone loss owing to late complications of injured teeth.1,2 The past few decades have witnessed a noteworthy diminution in the prevalence of tooth loss in many developed countries.3 Simultaneously, there is also an upturn in patient's life expectancy along with their inclination for fixed restoration, instead of removable prosthesis.4 When the endosseous implant cannot be placed in an ideal location due to resorption of alveolar bone, there is bound to be a negative effect on the emergence profile of the prosthesis, bucco-palatal relationship and embrassure space, which can affect the future of implant-supported restorations in both aesthetics and function.5
Augmentation of the alveolar ridge by means of a split crest technique and bone expansion is a feasible alternative to consent implant placement in cases where the bucco-lingual bone thickness is 3 mm or more but <6 mm. This ensures, minimum of 1 mm of trabecular bone to be present between the two cortical plates for alveolar ridge width of 3 mm. This ensures 1.5 mm of cortical and cancellous bone on both sides of the split ridge and allows the bone to expand and sustain a good blood supply.
2. Methods
In this study, two approaches of implant placement using split crest technique to augment narrow alveolar ridges along with the implant success and survival was compared and assessed.
Ten patients belonging to ASA I and II irrespective of their gender, who visited the Department of Oral and Maxillofacial Surgery, College of Dental Sciences, Davangere with the complaint of partial edentulism having crestal width of ≤4.0 mm favouring fixed prosthesis, were included in the study. Patients with severely atrophic ridges (2 mm or less), concomitant vertical defect, history of tobacco abuse for more than 15 cigarettes/day, radiation history in the head and neck region, undergoing active chemotherapy for management of malignant tumors and those suffering from systemic diseases such as bleeding and clotting disorders, non compensated diabetes, cardiovascular diseases hypertension, severe renal or liver disease, history of psychiatric illness etc were excluded from the study. Measurements were made by means of CBCT. Cases were selected only when the vertical dimension of the edentulous ridge was optimal for placement of implant guided by CBCT.
Patients were randomly allocated into two groups. Once CBCT was done and the horizontal and vertical dimensions were calculated, randomization to perform immediate or delayed technique was decided by lottery system where the individual taking out the lottery was blinded. Group I (immediate group) patients (2 males, 3 females) underwent immediate placement of implants following the ridge split procedure. Group II (delayed group) patients (5 females) underwent delayed placement of implants following the ridge split procedure. The span of edentulous ridge was in the range of (7.70–25.08 mm) with mean length being 14.54 ± 5.29 mm.
2.1. Surgical procedure
2.1.1. Delayed technique
After reflection of full thickness mucoperiosteal flap crestal osteotomy was started 2 mm away from adjacent tooth, using a diamond disc/#701 tungsten carbide straight fissure bur. Length of the horizontal cut was determined, considering the number of implants and the space between the implants to be placed. Thereafter vertical osteotomies which was approximately half the length of the proposed implants height were performed using #701 straight fissure bur at the mesial and distal ends of horizontal osteotomy, following which lateral expansion was achieved by using guided delicate forces causing a favourable greenstick fracture of the buccal cortical plate using straight and curved osteotomes. Following this maneuver progressive sizes of osteotomes and bone expanders were introduced to increase inter cortical gap and achieve desired amount of horizontal ridge expansion [Fig. 1].
Fig. 1.
Pre-operative ridge and Augmentation achieved.
The expansion achieved was measured intra operatively using Castrovejo surgical calipers for clinical estimation of the amount of expansion achieved. Post-operative CBCT was done to assess the amount of expansion achieved [Fig. 2].
Fig. 2.
Measurement of Post-Operative Crestal width using CBCT.
2.1.1.1. Second stage of surgery
The amount of bone formation was noticed by raising a buccal flap after four weeks of healing period over the crest which was followed by placement of two stage endosseous implants. A crestal incision to expose the crestal cut was performed. The buccal flap had to be minimally reflected to preserve the blood supply for the buccal cortical plate. Also, a small chisel was used to carefully separate and mobilize the segmented bone, provoking a greenstick fracture. The blood supply on the buccal aspect of the displaced buccal plate was maintained. After preparation of the implant sites using twist drills and osteotomes, the implants were placed and bone graft augmentation was performed. Adjunctive material was not used in all cases. Tension-free soft tissue closure was achieved in all cases. After four months of post-operative period, healing abutments were placed. After two months the healing abutment was removed and a closed tray impression was made with implant analogues/implant copings in place using silicon impression material (putty and light body). Once the final prosthesis was prepared the crown cementation was done on the abutment after establishing proper occlusion.
2.1.2. Immediate technique
The surgical procedure of ridge augmentation using split crest technique was similar to that performed for delayed technique, the only difference was that the implants were placed simultaneously at the same time using surgical guide.
Graft was not used during the surgical procedure except for two cases of the immediate technique where it was felt that the immediate intra-op stability of the implants was slightly compromised. Though all implants had primary stability, the periotest value of these two implants was comparatively low due to less amount of basal bone available. Hence, bone void filler was mixed with patient's blood and packed around the implants and inter-cortical gap.
2.1.2.1. Implant size
The sizes of the implants were selected conferring to the available bone width and height.
2.1.2.2. Width measurement of the alveolar ridge
The criteria evaluated were pre-operative crestal width (T0), postoperative crestal width (T1) and post-operative crestal width at 6 months (T2). All the measurements were made between the cervical edges of the teeth mesial and distal to the edentulous ridge by means of CBCT using PlanmecaRomexis Image Viewer Software. T0, T1 and T2 were measured by taking 2 mm sections of the coronal view for posterior jaw area and sagittal view for anterior jaw region. The crestal width was measured 1 mm below the crest apex at all sections and meancrestal width was taken by dividing the sum of all measurements by the number of sections for all the 10 patients using CBCT, which was ≤4.00 mm for all the patients.
2.1.2.3. Implant success criteria
Implant success rate was evaluated on the basis of the criterias given by BUSER et al., in 1990.
2.1.2.3.1. Measurement of implant stability/mobility
Stability of implant was assessed using PERIOTEST M (Medizintechnik gulden, Siemens) wireless hand set at immediate intra-op, 4 months post-op (at the time of placing healing abutments) and at 6 months post-op (at the time of placing final abutments). The PERIOTEST M gives readings ranging from (−8 to +50) where −8 being the best reading and +50 being the worst.The Periotest M takes measurements at all stages of the implant process: directly after implantation, to measure primary stability, following the healing phase to determine that the required degree of osseointegration has taken place to enable pressure to be applied to the implant, and following completion of the prosthetic, to enable any negative developments to be recognized at an early stage.6
METHOD OF EVALUATION:The jaw to be tested was positioned horizontally and the probe was levelled at a right angle to the post, and its contact was made as close to the bony crest as possible. All of the implants were tested in lateral direction that is either in labio/bucco palatal direction for maxillary Implants and labio/bucco lingual direction in mandibular Implants.
2.1.2.4. Assessment of post- operative paresthesia/Dysasthesia
Patients were inquired about presence of any itching/tingling and pain/burning sensations at 1st postoperative day, 1 Week and 1 month and the objective assessment was done using two point discrimination test.
2.1.2.5. Assessment of presence/absence of peri-implant radiolucency
This was done by taking routine IOPA's (Intra Oral Periapical Radiographs) at 2 months, 4 months and 6 month time intervals.
2.1.2.6. Implant survival criteria
Implant survival rate was assessed by presence/absence of asymptomatic loaded implants at 6 month time interval.
2.1.2.7. Statistical analysis
All the data collected at various time interval was analyzed using SPSS software version 22.
Parametric data was analyzed using Unpaired ‘t’ test, Paired ‘t’ test, ANOVA and Pearson's Correlation, (p value was set at 0.05).
3. Results
In our study the augmentation achieved in the two groups was compared using Unpaired't' test and no statistical difference was found among the two groups. (P = 0.418) The measurements of T0, T1 and T2 was in the range of (2.51–3.43 mm) mean value 2.82 ± 0.27 mm, (5.74–7.16 mm) mean value 6.35 ± 0.48 mm, (5.59–7.03 mm) mean value 6.12 ± 0.45 mm respectively with no statistical difference [Table 1]. The mean augmentation achieved was obtained by subtracting the mean value of T1 from mean value of T0. The mean augmentation achieved in the immediate technique group was 3.66 ± 0.54 mm [Table 2] which was more as compared to delayed technique group 3.39 ± 0.45 mm [Table 3]. This could be attributed to the immediate placement of implants. Similar results were also seen in studies by Jawad A. Abu Tair7 who achieved average gain in width of 3.22 ± 0.97 mm and Nicolae Chale et al.8 where they achieved an expansion of 3–4 mm. Still the augmentation achieved in both of the groups was found to be adequate for placing wider diameter implants.
Table 1.
Pre-operative crestal width of edentulous ridge (T0), post-operative crestal width of edentulous ridge (T1), post-operative crestal width of edentulous ridge- six months (T2).
| Case No. | Range of Width (T0) | Mean Width (T0) | Range of Width (T1) | Mean Width (T1) | Range of Width (T2) | Mean Width (T2) |
|---|---|---|---|---|---|---|
| Case: 1 | 2.82–2.90 mm | 2.85 mm | 5.62–5.83 mm | 5.74 mm | 5.55–5.63 mm | 5.59 mm |
| Case: 2 | 2.27–3.33 mm | 2.76 mm | 6.37–8.33 mm | 7.16 mm | 6.05–8.23 mm | 7.03 mm |
| Case: 3 | 2.57–3.00 mm | 2.75 mm | 6.45–7.18 mm | 6.78 mm | 6.30–6.90 mm | 6.52 mm |
| Case: 4 | 2.28–2.76 mm | 2.53 mm | 5.74–5.98 mm | 5.86 mm | 5.57–5.81 mm | 5.69 mm |
| Case: 5 | 3.00–3.90 mm | 3.43 mm | 5.94–6.91 mm | 6.45 mm | 5.79–6.61 mm | 6.23 mm |
| Case: 6 | 2.72–3.15 mm | 2.99 mm | 6.18–7.48 mm | 6.87 mm | 5.96–7.13 mm | 6.47 mm |
| Case: 7 | 2.86–3.15 mm | 3.02 mm | 5.86–6.12 mm | 6.05 mm | 5.76–6.00 mm | 5.92 mm |
| Case: 8 | 2.43–3.12 mm | 2.73 mm | 6.19–6.73 mm | 6.58 mm | 6.05–6.51 mm | 6.28 mm |
| Case: 9 | 2.33–2.84 mm | 2.51 mm | 5.78–6.00 mm | 5.89 mm | 5.62–5.80 mm | 5.71 mm |
| Case: 10 |
2.29–2.90 mm |
2.64 mm |
5.91–6.23 mm |
6.13 mm |
5.78–6.11 mm |
5.84 mm |
|
N |
Mean Width (T0) |
Standard Deviation |
Mean Width (T1) |
Standard Deviation |
Mean Width (T1) |
Standard Deviation |
| 10 | 2.82 mm | 0.27 mm | 6.35 mm | 0.48 mm | 6.12 mm | 0.45 mm |
Table 2.
Augmentation achieved – immediate technique group.
| CASE No. | (T0) Mean | (T1) Mean | Augmentation achieved (T1-T0) Mean | |
|---|---|---|---|---|
| CASE 2 | 2.76 mm | 7.16 mm | 4.40 mm | |
| CASE 3 | 2.75 mm | 6.78 mm | 4.03 mm | |
| CASE 7 | 3.02 mm | 6.05 mm | 3.03 mm | |
| CASE 9 | 2.51 mm | 5.89 mm | 3.38 mm | |
| CASE 10 |
2.64 mm |
6.13 mm |
3.49 mm |
|
|
Immediate Group (N) |
Mean Augmentation achieved |
Standard Deviation |
Minimum |
Maximum |
| 05 | 3.66 mm | 0.54 mm | 3.03 mm | 4.40 mm |
Table 3.
Augmentation achieved – delayed technique group.
| CASE No. | (T0) Mean | (T1) Mean | Augmentation achieved (T1-T0) Mean | |
|---|---|---|---|---|
| CASE 1 | 2.85 mm | 5.74 mm | 2.89 mm | |
| CASE 4 | 2.53 mm | 5.86 mm | 3.33 mm | |
| CASE 5 | 3.43 mm | 6.45 mm | 3.02 mm | |
| CASE 6 | 2.99 mm | 6.87 mm | 3.88 mm | |
| CASE 8 |
2.73 mm |
6.58 mm |
3.85 mm |
|
|
Delayed Group (N) |
Mean Augmentation achieved |
Standard Deviation |
Minimum |
Maximum |
| 05 | 3.39 mm | 0.45 mm | 2.89 mm | 3.88 mm |
The augmentation achieved was also compared to the area of the jaw and also with the length of the edentulous span irrespective of the technique used which was found to be statistically not significant (P = 0.456). But clinically the surgical procedure was easier to perform in maxilla followed by posterior mandible and lastly anterior mandible.
When the amount of augmentation accomplished was correlated with the length of the edentulous span using Pearsons Correlation, a high positive correlation between the two variables (R = 0.845) was found. It implies that as the length of the edentulous span increases the amount of augmentation obtained also increases significantly irrespective of the area of the jaw. Which is similar to what has been stated by Misch C M et al.9
The periotest value (PTV) was evaluated for the measurement of implant stability. Mean (PTV) obtained in immediate technique group for Intra-Op, 4 months 6 months was (+0.66), (−1.4), (−1.9) respectively while in delayed technique group was (−0.94), (−2.70) and (−3.08). No patient showed the presence of peri-implant radiolucency which was assessed by taking periodic IOPA's at 2, 4 & 6 months indicating 100% success rate for implants placed in both the groups. All patients showed presence of loaded asymptomatic implants at 6 months post loading time period indicating 100% survival rate of all implants placed in both the groups.
There was no complication associated with all the 19 implants placed in both the techniques. The success and survival rates were 100% within the limits of the study. Similar results were reported in other studies done by ChiapascoM et al.10 (98%–100% for ridge expansion techniques), Buser et al.11 (5 year success rate of 98.3%).
4. Discussion
Dental implants have come to be the standard care of rehabilitation of missing teeth.12 Substituting missing teeth with endosseous implants and an implant reinforced prosthesis has become the typical care and first line of treatment for long lasting rehabilitation revolutionizing the research and technology of implants in the last two decades.13
Reduction of stress concentration at crestal bone region requires augmentation of scarce alveolar ridges in implant surgery, since facio-palatal bone is often only 4–6 mm wide at the crest with/without an “hourglass” facial deformity.14,15 For a favourable outcome, a minimum of 6 mm ridge width is essential, therefore leading to a minimum of 1–1.5 mm bone around the implant.16
Thinner ridges (<3.5 mm) can be expanded with superior instrumentation reducing the risk for fracture, trauma and bone perforations owing to the dynamic viscoelastic nature of the bone. As the trabecular bone softens, the elastic modulus decreases and the viscoelastic nature of the ridge increases. Hence, the less dense the bone, the easier and more likely the bone expansion.15
As such, a number of techniques have been employed for augmenting adequate bone width, which can be performed either in combination with the implant placement (one stage/simultaneous approach), as this would be usually associated with dehiscence or fenestration, causing bony defects which can be prevented by an alternative technique (two stage/staged approach) wherein the surgical placement of the implants follows a period of healing of augmented thin alveolar ridges.
Different surgical techniques can be utilized to reconstruct the narrow alveolar ridge. These techniques range from guided tissue regeneration, autogenous and allograft bone blocks, to distraction osteogenesis but these methods have several drawbacks. The use of crest split technique offers several advantages: the space created by expansion, heals like an extraction socket. In selected cases, patients can wear their denture after surgery. Secondary surgical sites are not a requirement, and immediate implant placement can be attained during ridge expansion. Though, this technique is more suitable for maxilla and can be done in posterior mandibular region if satisfactory condition exists.17
This study indicates that both the techniques are feasible on the basis of success and survival rate of implants placed having advantages of their own where immediate technique provides advantages like reduced time and cost of treatment but has disadvantages like mal-fracture of bony segment, lack of implant stability and compromised implant placement in the bucco-lingual and apico-coronal direction. Whereas delayed technique offers advantage of lack of complications but it increases the overall time and cost of the treatment. The split crest technique is very efficient for horizontal augmentation in severely atrophic and narrow alveolar ridges to provide adequate amount of bony base for placement of wider diameter implants.
5. Conclusion
To conclude with, both the techniques were comparable on the basis of extent of augmentation achieved and success and survival rates of implants placed. However, we do consider that the above study provides adequate evidence to start larger multicenter studies having protocol similar to our study. Such studies would be more conclusive.
Ethical approval
“All procedures performed in study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.”
Funding organization
None.
Declaration of competing interest
Authors declare that they have no conflict of interest.
References
- 1.Studer S., Naef R., Scharer P. Adjustment of localized alveolarridge defects by soft tissue transplantation to improve mucogingival esthetics: a proposal for clinical classification and an evaluation of procedures. Quintessence Int. 1997;28:785–805. [PubMed] [Google Scholar]
- 2.Pertl C., Ebeleseder K., Lorenzoni M., Bantleon H.P., Wegscheider W.A. Contemporary treatment of the resorbed avulsed tooth: a case report. Int Endod J. 1999;32:332–336. doi: 10.1046/j.1365-2591.1999.00234.x. [DOI] [PubMed] [Google Scholar]
- 3.Mojon P., Thomason J.M., Walls A.W.G. The impact of falling rates of edentulism. Int J Prosthodont (IJP) 2004;17:434–440. [PubMed] [Google Scholar]
- 4.Preciado A., Del Río J., Suárez-García M.-J., Montero J., Lynch C.D., Castillo-Oyagüe R. Differences in impact of patient and prosthetic characteristics on oral health-related quality of life among implant-retained overdenture wearers. J Dent. 2012;40:857–865. doi: 10.1016/j.jdent.2012.07.006. [DOI] [PubMed] [Google Scholar]
- 5.Ferrigno N., Laureti M. Surgical advantages with ITITE implants placement in conjunction with split crest technique. 18-month results of an ongoing prospective study. Clin Oral Implants Res. 2005;16(2):147–155. doi: 10.1111/j.1600-0501.2005.01125.x. [DOI] [PubMed] [Google Scholar]
- 6.Cranin A.N., DeGradoJKaufman M., Baraoidan M., DiGregorio R., Batgitis G., Lee Z. Evaluation of the Periotest as a diagnostic tool for dental implants. J Oral Implantol. 1998;24(3):139–146. doi: 10.1563/1548-1336(1998)024<0139:EOTPAA>2.3.CO;2. [DOI] [PubMed] [Google Scholar]
- 7.Abu Tair J. A Modification of mandibular ridge splitting technique for horizontal augmentation of atrophic ridges. Ann Maxillofac Surg. 2014 Jan;4(1):19–23. doi: 10.4103/2231-0746.133066. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Chele Nicolae, Topalo Valentin, Dabja Ion, Racovita Daniila. Lateral bone expansion for immediate placement of endosseous dental implants. Rom J Oral Rehabil. January 2011;3(No.1) [Google Scholar]
- 9.Misch C.M. Implant site development using ridge splitting techniques. Oral Maxillofac Surg Clin North Am. 2004 Feb;16(1):65–74. doi: 10.1016/j.coms.2003.10.001. [DOI] [PubMed] [Google Scholar]
- 10.Chiapasco M., Ferrini F., Casentini P., Accardi S., Zaniboni M. Dental implants placed in expanded narrow edentulous ridges with the Extension Crest device. A 1-3year multicenter follow-up study. Clin Oral Implants Res. 2006 Jun;17(3):265–272. doi: 10.1111/j.1600-0501.2005.01196.x. [DOI] [PubMed] [Google Scholar]
- 11.Buser D., Ingimarsson S., Dula K., Lussi A., Hirt H.P., Belser U.C. Long-term stability of osseointegrated implants in augmented bone: a 5-year prospective study in partially edentulous patients. Int J Periodontics Restor Dent. 2002 Apr;22(2):109–117. [PubMed] [Google Scholar]
- 12.Karthik K., Sivakumar Sivaraj, Thangaswamy V. Evaluation of implant success: a review of past and present concepts. J Pharm BioAllied Sci. 2013 Jun;5(Suppl1):S117–S119. doi: 10.4103/0975-7406.113310. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Baqain Z.H., Moqbel W.Y., Sawair F.A. Early dental implant failure: risk factors. Br J Oral Maxillofac Surg. 2012;50:239–243. doi: 10.1016/j.bjoms.2011.04.074. [DOI] [PubMed] [Google Scholar]
- 14.Lieberman J.R., Friedlander G.E. first ed. © Humana Press; Totowa, NJ: 2005. Bone Regeneration and Repair; pp. 195–196. [Google Scholar]
- 15.Misch C.E. Density of bone: effect on treatment plans, surgical approach, healing, and progressive bone loading. Int J Oral Implant. 1990;6:23–31. [PubMed] [Google Scholar]
- 16.Tatum H., Jr. Maxillary and sinus implant reconstructions. Dent Clin North Am. 1986;30:207–229. [PubMed] [Google Scholar]
- 17.Basa S., Varol A., Turker N. Alternative bone expansion technique for immediate placement of implants in the edentulous posterior mandibular ridge: a clinical report. Int J Oral Maxillofac Implants. 2004;19(4):554–558. [PubMed] [Google Scholar]