Long-term outcomes from implants installed by using split-crest technique in posterior maxillae: 10 years of follow-up

Fracture rate and risk factors associated with the fracture of narrow diameter implants: A long-term retrospective analysis

OBJECTIVES

The objective of this long-term retrospective study was to evaluate the fracture rate and the risk factors associated with the fracture of 3.3 mm narrow diameter implants (NDIs).

MATERIALS AND METHODS

A total of 524 records of patients rehabilitated with 3.3 mm NDIs between 1997 and 2015 were assessed. Data on patients, implants, and prostheses were collected, and descriptive analysis of the variables was performed. NDIs were separated into 2 groups: "fractured" and "non-fractured", and a multilevel logistic regression model was applied to identify the risk factors associated with NDI fracture.

RESULTS

Eighty-four patients were removed from the analysis for interrupting follow-up or presenting failures other than fractures. Of the 440 patients included (64.66 ± 13.4 years), 272 were females (61.8%), and 168 males (38.2%), and mean follow-up time was 129 ± 47.1 months. Of the 1428 NDIs, 15 (1.05%) in 9 patients (2.04%) fractured during the studied period. Ten fractures (66.66%) happened in 6 patients (66.66%) showing signs of parafunction. NDI with modified sandblasted, large grit, acid-etched surface was the only implant variable to show a protective statistical significance (p = .0439).

CONCLUSIONS

NDI fracture was a rare event in the studied sample. NDIs manufactured with modified sandblasted, large grit, acid-etched surface may provide extra protection against NDI fracture. Patient-specific factors and implant characteristics should be carefully considered to limit the risk of fracture of 3.3 mm NDIs.

Alveolar ridge bone changes in patients treated with the split-crest technique with simultaneous implant placement: A retrospective longitudinal observational study

OBJECTIVES

To investigate long-term alveolar ridge bone changes in patients treated with the split-crest technique (SCT) with simultaneous implant placement.

MATERIALS AND METHODS

Alveolar ridge width (ARW) was measured with a caliper immediately before (ARW1) and after SCT (ARW2) with a caliper. Existing CBCT scans taken at least 5 years postoperatively were used to assess the healed ARW (ARWF), buccal bone thickness (BBT), and lingual/palatal bone thickness (L/PBT) at 0, 3, and 5 mm apically from implant platform level (IPL). The distance between IPL and buccal bone crest (IPL-BBC) was also measured. Findings were compared with Wilcoxon and Student's t tests (p < .05).

RESULTS

Records of thirty patients with 85 implants were included. Eleven patients (31 implants) presented CBCT scans taken in two separate occasions, resulting in 116 measurements. Tomographic follow-up ranged from 5 to 18 years (11.5 ± 4.18 years). Mean ARW increased from 3.2 ± 0.6 to 6.6 ± 0.48 mm after SCT, but significantly reduced overtime to 4.46 ± 0.83 mm (ARWF) (p < .0001). Mean BBT was 0.5 ± 0.9, 1.3 ± 0.9, and 2.0 ± 1.2 mm, while mean L/PBT was 0.9 ± 0.7, 1.6 ± 0.9, and 2.1 ± 1.0 mm at 0, 3, and 5 mm from IPL, respectively. IPL-BBC distance varied up to 8.7 mm (1.4 ± 2.0 mm), with 56/116 measurements (51/85 implants) showing IPL-BBC = 0 mm.

CONCLUSION

Although SCT with simultaneous implant placement can predictably increase ARW postoperatively, ARW tended to significantly reduce over time, due to reductions in BBT and L/PBT, especially coronally. Nonetheless, 60% of the implants still presented some buccal bone at IPL.

Use of narrow-diameter implants in the posterior segments of the jaws: A retrospective observational study of 2 to 11 years

STATEMENT OF PROBLEM

The placement of narrow-diameter implants (NDIs) in the posterior region is still debated in view of the high biomechanical risks in these areas.

PURPOSE

The purpose of this retrospective observational study was to evaluate the success and survival rates of NDIs restored with fixed prostheses in the posterior region (primary outcome) and analyze whether splinting multiple units (prosthesis design) affects the biological and mechanical complications (secondary outcome).

MATERIAL AND METHODS

Dental records from 2 private clinics were reviewed for NDIs in the posterior region installed between 2009 and 2018. Ninety study participants (58 women and 32 men) aged between 21 and 84 years (mean age 49.9 years) were recalled for the assessment of implant survival and success of 160 NDIs previously provided for partial posterior edentulism associated with moderate horizontal bone loss or reduced interradicular space (105 premolars and 55 molars). The implants were restored with metal-ceramic single crowns or splinted multiple-unit prostheses, either screw-retained or cemented on custom (n=100) or stock titanium abutments (n=60). Peri-implant probing depth (PPD), bleeding on probing (BOP), bone quality, type of edentulism, and patient satisfaction were scored. The chi-squared test for independence and 2-sample Welch t test were performed for statistical analysis (α=.05).

RESULTS

The overall success rate was 89.37%. One implant had been removed 4 years after loading, another after 9 years, yielding a cumulative survival rate of 98.75%. Fourteen implants exhibited PPD > 5 mm. One implant and 1 abutment screw fractured, and 16 restorations demonstrated porcelain chipping. The chi-squared test showed no significant relationship between prosthetic design and complications whether biological (P=.087) or mechanical (P=.805). Eighty-two percent of patients were satisfied with esthetics, 76% with function, 85% with total duration of treatment, and 90% with overall treatment cost.

CONCLUSIONS

Within the limitations of this retrospective study, NDIs may be considered a reliable option to replace posterior teeth. The prosthetic design had no significant impact on biological or mechanical complications.

The efficacy of alveolar ridge split on implants: a systematic review and meta-analysis

OBJECTIVES

To evaluate the effects of the alveolar ridge split (ARS) technique on gained horizontal width of the alveolar ridge and implant survival rate.

MATERIALS AND METHODS

Electronic searching was performed in six electronic databases (Pubmed, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, China National Knowledge Infrastructure, and SIGLE) from January 1, 2010, to November 1, 2023. Two authors performed study selection, data extraction, and study qualities (ROBINS-I and RoB 2.0) independently. Meta-analysis was performed by Comprehensive meta-analysis 3.0.

RESULTS

24 included studies were observational, and 1 study was a randomized controlled trial (RCT). 14 studies investigated the gained width of the horizontal alveolar ridge, and 17 examined the implants' survival rate. For assessment of risk of bias, nine studies were high risk of bias and 16 studies were moderate risk of bias. Meta-analysis demonstrated that the pooled gained alveolar ridge width was 3.348 mm (95%CI: 4.163 mm, 2.533 mm), and the implant survival rate was 98.1% (95%CI: 98.9%, 96.9%). Seven studies showed seven different complications including exposure, infection, bad split, dehiscence, fracture, paresthesia and soft tissue retraction.

CONCLUSION

Recent ARS technique seems to be an effective method of bone augmentation with enough gained width and a high implant survival rate. Further long-term and RCTs research remains needed to enhance the study quality.

CLINICAL RELEVANCE

The ARS technique could generate sufficient bone volume, and implants had a high-level survival rate. Therefore, ARS has been proposed to be a reliable horizontal bone augmentation technique that creates good conditions for the implantation of narrow alveolar crests.

Lateral augmentation of the jaw by the split expansion ridge technique. A critical review

Bone augmentation has become a routine procedure to enhance and/or repair a deficient or resorbed alveolar ridge for predictable and successful implant placement. The split expansion ridge i.e., the alveolar ridge splitting (ARS) procedure, is one of the less invasive procedures, and is characterized by minor morbidity. This would allow to widen narrow ridges in order to allow implant reconstruction in a sufficient bone volume. Its efficacy and long-term stability rely upon clinical opinions and long-term retrospective studies, while prospective comparative studies and randomized controlled trials are rare. This critical review presents the development of this technique, describes the surgical procedure, and provides technical notes and modifications. The learning curve and in-depth knowledge of the oral anatomy, as well as the recognition of incidence and management of complications are of utmost importance in the clinical application of the ARS procedure.

Short Narrow Dental Implants versus Long Narrow Dental Implants in Fixed Prostheses: A Prospective Clinical Study

There is a paucity of studies that assess short and narrow dental implants. This prospective study aimed to evaluate the performance of both short (≤8 mm) and narrow (≤3.5 mm width) dental implants supporting fixed prostheses in the atrophic maxilla or mandible. Towards that aim, patients with short implants were included in the study. The control group was those with long and narrow dental implants (length > 8 mm and diameter ≤ 3.5 mm). Clinical and demographic variables were extracted from clinical records. During the follow-up, implant survival and marginal bone loss were evaluated and statistically analysed. Forty-one implants were included (18 and 23 implants in the test and control groups, respectively). The median follow-up time was 26 months since insertion in both groups. The results revealed that there was no implant failure and no statistically significant differences in terms of marginal bone loss. Only one screw-loosening effect occurred in the short implants group. Short, narrow dental implants could be an alternative for the restoration of severely resorbed jaws.

Short-Term Evaluation of Prosthetic Rehabilitation of Thin Wiry Ridge by Ridge Splitting and Simultaneous Implants Placement: Non-randomized Control Trial

Objective  This article evaluates the success of prosthetic rehabilitation of thin wiry ridge and implants placed simultaneously in splitted ridge both clinically and radiographically.

Materials and Methods  Twenty-one participants were enrolled of which 13 patients (8 females and 5 males) were suffering from maxillary ridge atrophy and 8 patients (5 females and 3 males) had mandibular ridge atrophy; a total of 42 implants were performed using the ridge expansion technique. The expansion was performed using the conventional disk technique, piezoelectric corticotomy, and self-threading expanders. Implants were placed and loaded with fixed partial denture after 4 months for the mandible and 6 months for the maxilla. Implant stability quotient (ISQ) was measured at T0 (implant placement) and TL (loading). Crestal bone levels were measured at different times: T0, TL, and T12 (12 months). Evaluation of prosthetic and surgical complications was carried out. Data were analyzed and compared using analysis of variance and paired t -tests at a significance level of 5%.

Results  All implants met the criteria for success. All implants showed a higher mean bone loss from T0 to TL (1.259 ± 0.3020) than from TL to T12 (0.505 ± 0.163) with a statistically significant difference ( p  < 0.0001). ISQ values sharply increased at the time of loading (72.52 ± 2.734) than at implant insertion (44.5 ± 4.062) with a significant difference ( p  < 0.0001). Minor prosthetic and surgical complications were reported.

Conclusion  The results from this study support the efficacy of prosthetic rehabilitation of thin wiry ridge using split ridge technique and the success of implants placed simultaneously in splitted ridge.

Autogenous Bone and Bioactive Glass around Implants Placed Simultaneously with Ridge Splitting for the Treatment of Horizontal Bony Defects: A Randomised Clinical Trial

Objective

To compare using autogenous bone with or without bioactive glass in ridge splitting of horizontal bone defects combined with simultaneous implant placement.

Materials and Methods

In control group, bone expansion was performed and autogenous bone was used to augment the intercortical bone defect. In study group, autogenous bone was mixed with bioactive glass (1 : 1 in volume). In both groups, the implants were inserted simultaneously with ridge splitting. Six months following implant insertion, bone width and height were evaluated. Statistical analysis utilizing paired Student's t-test was used for comparing results within the same group, whereas independent samples t-test was used for intergroup variables comparison.

Results

The mean bone width and labial and mesiodistal crestal bone height values were increased significantly in both groups from baseline to 6 months postoperatively. Comparing the two groups showed nonstatistical significant difference regarding the labial crestal bone loss, while the ridge width gain values were significantly higher in the study group than in the control group. The mesiodistal bone loss was significantly higher in control group than in study group.

Conclusion

Autogenous bone was mixed with bioactive glass (1 : 1 in volume) to fill intercortical defect created after ridge splitting to decrease peri-implant bone resorption associated with autogenous bone alone. This trial is registered with clinical trial registration: NCT04814160.

Split Crest Technique with Immediate Implant to Treat Horizontal Defects of the Alveolar Ridge: Analysis of Increased Thickness and Implant Survival

Objective

To assess bone thickness augmentation and implant survival in ridges with horizontal atrophy managed through split crest technique with concomitant installation of dental implants.

Materials and Methods

Thirteen patients with maxillary bone atrophy underwent surgery and had their bone thickness assessed through cone beam computed tomography 6 months pre- and postoperatively. Comparative measurements of initial and final bone height and thickness were taken using Dolphin Imaging^® 11.5 software. The distance between the nasal fossa floor or the maxillary sinus and the alveolar crest determined the bone height, while the measurement of bone thickness took into account the distance between the vestibular cortical bone and the palatal cortical bone at the crest level, and at 5 mm and 10 mm from it.

Results

The bone height loss of 0.68 mm was statistically significant (p = 0.01). The average horizontal bone gain was 3.45 mm at ridge level, 3.03 mm at 5 mm from it and 2.42 mm at 10 mm from it. The mean horizontal gain for the three regions was 2.97 mm, and the values were statistically significant for all three regions assessed (p < 0.01). No complications were associated with the surgical procedures, and 23 implants were installed following the surgical expansion. No implants were lost (100% survival).

Conclusion

The split crest technique proved to be viable and predictable, enabling a significant increase in ridge thickness and a high percentage of implant survival.

Maxillary Alveolar Ridge Expansion with Split-Crest Technique Compared with Lateral Ridge Augmentation with Autogenous Bone Block Graft: a Systematic Review

Objectives

The objective of the present systematic review was to test the hypothesis of no difference in implant treatment outcome after maxillary alveolar ridge expansion with split-crest technique compared with lateral ridge augmentation with autogenous bone block graft.

Material and Methods

A MEDLINE (PubMed), Embase and Cochrane Library search in combination with a hand-search of relevant journals was conducted. Human studies published in English until 8th of February, 2018 were included.

Results

One comparative and four noncomparative studies fulfilled the inclusion criteria. Both treatment modalities disclosed high survival rate of implants with few complications. High survival rate of prosthesis, implant stability values, limited peri-implant marginal bone loss and gain in maxillary alveolar ridge width were reported with the split-crest technique. Patient-reported outcome measure and length of patient treatment time was not assessed in any of the included studies.

Conclusions

The split-crest technique seems to be useful for horizontal augmentation of maxillary alveolar deficiencies with high survival rate of prosthesis and implants. However, further long-term randomized controlled trials with larger patient sample as well as assessment of patient-reported outcome measures and patient treatment time are needed before well-defined conclusions can be provided about the two treatment modalities.

The radiological evaluation of posterior superior alveolar artery topography by using computed tomography

BACKGROUND

Posterior superior alveolar artery (PSAA) is the most important limiting anatomic structure while lateral approach sinus surgeries. PSAA should be taken into consideration to avoid bleeding during preparation of bony window.

PURPOSE

The aim of this article was to inform topography of PSAA and to evaluate measurements of this vital structure.

MATERIALS AND METHODS

Three hundred and fifty-four cone-beam computed tomography (CBCT) images of PSAA from 177 patients were evaluated retrospectively. Localization of PSAA, diameter of PSAA, classification of PSAA diameter, distance between PSAA and crest, buccal bone thickness, palatal bone thickness, crest height, and crest width were recorded for each posterior tooth separately.

RESULTS

The mean age of 177 patients was 54.05 ± 18.33 years. Although the most frequent localization of PSAA was intraosseous in premolar region, they were below Schneiderian membrane in molars. PSAA diameter was measured frequently less than 1 mm for all posterior teeth. Although palatal bone thickness was higher in premolar region than molars, no statistical relationship was found between tooth region and buccal bone thickness (P > 0.05). The width of residual ridge was measured both wider apically and posteriorly. Positive correlation was observed between buccal bone thickness and PSAA diameter in first molar and premolar regions (P < 0.05).

CONCLUSIONS

Detailed evaluation of patients by CBCT provided us the opportunity to draw topography of PSAA and inform about overall measurements of PSAA in all posterior teeth region.

Implant Stability in the Posterior Maxilla: A Controlled Clinical Trial

Aim

To evaluate the primary and secondary stability of implants in the posterior maxilla.

Methods

Patients were allocated into three groups: (A) native bone, (B) partially regenerated bone, and (C) nearly totally regenerated bone. Insertion torque (IT) and implant stability quotient (ISQ) were measured at placement, to evaluate whether satisfactory high primary stability (IT ≥ 45 N/cm; ISQ ≥ 60) was achieved; ISQ was measured 15, 30, 45, and 60 days after placement, to investigate the evolution to secondary stability.

Results

133 implants (Anyridge®, Megagen) were installed in 59 patients: 55 fixtures were placed in Group A, 57 in Group B, and 21 in Group C. Fifty-two implants had satisfactory high primary stability (IT ≥ 45 N/cm; ISQ ≥ 60). A positive correlation was found between all variables (IT, ISQ at t = 0, t = 60), and statistically higher IT and ISQ values were found for implants with satisfactory high primary stability. Significant differences were found for IT and ISQ between the groups (A, B, and C); however, no drops were reported in the median ISQ values during the healing period.

Conclusions

The evaluation of the primary and secondary implant stability may contribute to higher implant survival/success rates in critical areas, such as the regenerated posterior maxilla. The present study is registered in the ISRCTN registry with ID ISRCTN33469250.

Ridge Expansion by Flapless Split Crest and Immediate Implant Placement: Evolution of the Technique

Various treatment strategies and techniques have been proposed to perform alveolar bone augmentation; most common are guided bone regeneration, split crest, and autologous bone grafting. All of these techniques are reported to possess bone regenerative properties of osteoinduction and osteoconduction in relation to regenerated bone survival. Split crest resulted to be one of the most reliable bone augmentation techniques. In this study, we describe a new flapless-modified split crest technique on 4 patients to optimize the bone regeneration with bone augmentation implant insertion in 1 single stage. The rationale of this technique is to obtain a proper buccal cortex expansion preserving its vascular supply and avoiding periosteal elevation for better cortical bone preservation. The main advantages of this technique consist in a single surgical stage without donor sites, vascular periosteal preservation of vestibular cortical walls, preservation of alveolar bone height avoiding bone loss after implant kit drilling, and preservation of proper cortical thickness on both sides, thereby saving periosteal nourishment on the vestibular side. Indication for this technique could be extended to almost every implant insertion for alveolar height saving at drilling time for implant insertion, because of the alveolar crest shape.

The split crest technique and dental implants: a systematic review and meta-analysis

This systematic review aimed to determine: (1) the expected bone volume gain with the split crest technique, and (2) how the use of surgical instruments affects the performance of this technique. An electronic search was performed in the Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Embase, PubMed/MEDLINE, Scopus, and Web of Science databases. Twenty-seven articles met the selection criteria and were subjected to meta-analysis of bone gain and survival rate; 17 reported the use of conventional surgical instruments and nine the use of surgical ultrasound. A total of 4115 implants were installed in 1732 patients (average patient age 52 years). The overall implant survival rate was 97%. The average bone gain in studies that used conventional surgical instruments was 3.61mm, while this was 3.69mm in those that used ultrasound. Only two studies presented a low risk of bias. The greatest problems identified during the qualitative analysis were related to random selection of the population and the absence of statistical analysis. The split crest technique appears to be a promising and effective technique to gain bone width, regardless of the surgical instruments used. Considering the diversity of the studies and implant types, no definitive recommendations can be made, especially with regard to the best instruments and implant design to be used.

Is Alveolar Ridge Split a Risk Factor for Implant Survival?

PURPOSE

There is a paucity of studies that have assessed the long-term outcomes of the alveolar ridge split (ARS). This study evaluated the intraoperative and postoperative complications and assessed the placed dental implant and prosthesis.

MATERIALS AND METHODS

A retrospective study of the ARS was conducted in a single private dental clinic. The predictor variable was the ARS technique (1 stage vs 2 stages). The primary outcome was the dental implant survival rate. Secondary outcomes were intraoperative complications, marginal bone loss, prosthetic complications, and prosthesis success rate. Descriptive analysis was performed for patients' demographic data, implant details, and prosthetic complications. The Kaplan-Meier method was used to assess implant survival rate and prosthesis success rate.

RESULTS

Twenty patients (mean age, 55 ± 6 yr) had a mean follow-up time of 5 years. Delayed implant placement was performed when the residual alveolar bone width was narrower than 3 mm. No intraoperative or postoperative complications were reported. The survival rate of the 31 implants was 100% and the prosthesis success rate was 96.8%.

CONCLUSIONS

The ARS is an effective technique for horizontal bone augmentation in the mandible. Delayed dental implant placement when the alveolar bone width is narrower than 3 mm could minimize the risk of buccal wall fracture.

The alveolar ridge splitting/expansion technique: a systematic review

PURPOSE

The aim of this systematic review was to evaluate clinical, radiological and histological outcomes of the alveolar ridge splitting/expansion technique (ARST) with or without GBR.

MATERIALS AND METHODS

A screening of two databases MEDLINE (PubMed) and EMBASE (OVID) and hand search of articles were performed. Human and animal studies reporting on dental implants placed with simultaneous ARST up to May 31st 2014 were considered. Quality assessment of selected full-text articles was performed according to the ARRIVE guidelines and the Cochrane collaboration's tool to assess risk of bias.

RESULTS

Overall, 18 human and six animal studies (risk of bias: high/unclear) were included in this review. No randomized controlled trials were found. Due to the heterogeneity of study designs, definitions of success criteria, outcome variables, observation times and surgical procedures, no meta-analysis was performed. Reported survival (18 studies) and success (nine studies) rates ranged from 91.7 to 100% and 88.2 to 100%, respectively, with a mean follow-up of 1-10 years. Crestal bone level changes (∆CBL) in some studies indicate slightly higher bone loss before and after loading. Histologic and histomorphometric data from six animal studies confirm the crestal bone loss, particularly at buccal sites.

CONCLUSIONS

Within the limitations of this review, ARST seems to be a well-functioning one-stage alternative to extended two-stage horizontal grafting procedures. Data indicate that during healing and first year of loading, increased ∆CBL particularly at buccal sites must be anticipated. Additional horizontal GBR can help to preserve buccal bone height and width.

Horizontal Resorption of Fresh-Frozen Corticocancellous Bone Blocks in the Reconstruction of the Atrophic Maxilla at 5 Months

Background

Reliable implant-supported rehabilitation of an alveolar ridge needs sufficient volume of bone. In order to achieve a prosthetic-driven positioning, bone graft techniques may be required.

Purpose

This prospective cohort study aims to clinically evaluate the amount of resorption of corticocancellous fresh-frozen allografts bone blocks used in the reconstruction of the severe atrophic maxilla.

Materials and Methods

Twenty-two partial and totally edentulous patients underwent bone augmentation procedures with fresh-frozen allogenous blocks from the iliac crest under local anesthesia. Implants were inserted into the grafted sites after a healing period of 5 months. Final fixed prosthesis was delivered ± 4 months later. Ridge width analysis and measurements were performed with a caliper before and after grafting and at implant insertion. Bone biopsies were performed in 16 patients.

Results

A total of 98 onlay block allografts were used in 22 patients with an initial mean alveolar ridge width of 3.41 ± 1.36 mm. Early exposure of blocks was observed in four situations and one of these completely resorbed. Mean horizontal bone gain was 3.63 ± 1.28 mm (p < .01). Mean buccal bone resorption between allograph placement and the reopening stage was 0.49 ± 0.54 mm, meaning approximately 7.1% (95% confidence interval: [5.6%, 8.6%]) of total ridge width loss during the integration period. One hundred thirty dental implants were placed with good primary stability (≥ 30 Ncm). Four implants presented early failure before the prosthetic delivery (96.7% implant survival). All patients were successfully rehabilitated. Histomorphometric analysis revealed 20.9 ± 5.8% of vital bone in close contact to the remaining grafted bone. A positive strong correlation (adjusted R² = 0.44, p = .003) was found between healing time and vital bone percentage.

Conclusions

Augmentation procedures performed using fresh-frozen allografts from the iliac crest are a suitable alternative in the reconstruction of the atrophic maxilla with low resorption rate at 5 months, allowing proper stability of dental implants followed by fixed prosthetic rehabilitation.

Bone loss after ridge expansion with or without reflection of the periosteum

OBJECTIVE

To evaluate the role of the periosteum in preserving the buccal bone after ridge splitting and expansion with simultaneous implant placement.

MATERIAL AND METHODS

In 12 miniature pigs, the mandibular premolars and first molars were removed together with the interdental bone septa and the buccal bone. Three months later, ridge splitting and expansion of the buccal plate was performed with simultaneous placement of two titanium implants per quadrant. Access by a mucosal flap (MF) was prepared on test sides, while a mucoperiosteal flap (MPF) with complete denudation of the buccal bone was increased on control sides. After healing periods of six and 12 weeks, the animals were sacrificed for histologic and histometric evaluation.

RESULTS

In the MF group, all 16 implants were osseointegrated, while in the MPF group, four of 16 implants were lost. Noticeable differences of bone levels on the implant surface and of the bone crest (BC) were found between the MF and the MPF group. Buccally after 6 weeks, the median distance between the implant shoulder (IS) and the coronal-most bone on the implant (cBIC) was for the MF group -1.42 ± 0.42 mm and for the MPF group -4.80 ± 2.72 mm (P = 0.15). The median distance between the IS and the buccal BC was -1.24 ± 0.51 mm and -2.78 ± 1.98 mm (P = 0.12) for the MF and MPF group, respectively. After 12 weeks, median IS-cBIC was -2.12 ± 0.84 mm for MF and -7.19 mm for MPF, while IS-BC was -2.08 ± 0.79 mm for MF and -5.96 mm for MPF. After 6 weeks, the median buccal bone thickness for MF and MPF was 0.01 and 0 mm (P < 0.001) at IS, 1.48 ± 0.97 mm and 0 ± 0.77 mm (P = 0.07) at 2 mm apical to IS, and 2.12 ± 1.19 mm and 1.72 ± 01.50 mm (P = 0.86) at 4 mm apical to IS, respectively. After 12 weeks, buccal bone thickness in the MF group was 0 mm at IS, 0.21 mm at 2 mm apical to IS, and 2.56 mm at 4 mm apical to IS, whereas complete loss of buccal bone was measured from IS to 4 mm apical to IS for the MPF group.

CONCLUSIONS

In this ridge expansion model in miniature pigs, buccal bone volume was significantly better preserved when the periosteum remained attached to the bone.