Histological assessment of augmented jaw bone utilizing a new collagen barrier membrane compared to a standard barrier membrane to protect a granular bone substitute material

Histological and radiological outcome after horizontal guided bone regeneration with bovine bone mineral alone or in combination with bone in edentulous atrophic maxilla: A randomized controlled trial

OBJECTIVE

To assess the radiological and histological outcome after horizontal guided bone regeneration (GBR) with deproteinized bovine bone mineral (DBBM) alone or in combination with particulate autogenous bone (PAB).

MATERIALS AND METHODS

Eighteen edentulous patients with an alveolar ridge of ≤4 mm were included in this split-mouth randomized controlled trial. Horizontal GBR with a graft composition of 100% DBBM (100:0) on one side and 90% DBBM and 10% PAB (90:10) on the other side were conducted in all patients. Cone beam computed tomography (CBCT) was obtained preoperatively, immediately postoperative, and after 10 months of healing. Width and volumetric changes in the alveolar process were measured on CBCT. Implants were placed after 10 months of graft healing where biopsies were obtained for histomorphometrical evaluation.

RESULTS

The gained widths were 4.9 (±2.4) mm (100:0) and 4.5 (±2.0) mm (90:10) at 3 mm from the top of the crest, and 5.6 (±1.3) mm (100:0) and 4.6 (±2.1) mm (90:10) at 6 mm from the top of the crest. The mean volumetric reductions were 32.8% (±23.8) (100:0) and 38.2% (±23.2) (90:10). Histomorphometry revealed that mean percentages of bone were 50.8% (±10.7) (100:0) and 46.4% (±11.3) (90:10), DBBM were 31.6% (±12.6) (100:0) and 35.4% (±14.8) (90:10), and non-mineralized tissue were 17.6% (±11.7; 100:0) and 18.2% (±18.2) (90:10). No significant differences were evident between in any evaluated parameters.

CONCLUSIONS

There were no additional effects of adding PAB to DBBM regarding bone formation, width changes, or volumetric changes after 10 months of graft healing.

Alveolar Ridge Preservation with a Novel Cross-Linked Collagen Sponge: Histological Findings from a Case Report

Alveolar ridge preservation (ARP) is a well-documented procedure to maintain bone volume after tooth extraction in order to place implants. However, at the end of the healing process, the residual biomaterial that is not reabsorbed remains embedded in the bone over time. Ribose cross-linked biomaterials demonstrated their ability to promote osteoconduction and complete resorption. The aim of this study was to evaluate the histological healing pattern of a novel ribose cross-linked collagen sponge used as a grafting material left exposed in human sockets at the time of tooth extraction. On a single patient, non-restorable lower first molars were extracted on both sides, and a ribose cross-linked collagen sponge was placed bilaterally in the cavities and left uncovered at the end of the surgery. After six months, core biopsies were taken immediately prior to implant placement; after the sample preparation, a histological analysis was performed. The results are very promising for substitution with newly formed bone and the amount of residual material. Ribose cross-linked collagen sponge could represent a valid alternative to conventional biomaterials for ARP procedures with no need for flap advancement and/or the addition of a membrane to cover the graft, reducing the invasiveness, complexity, and costs of the treatment.

A Comparison of In Vivo Bone Tissue Generation Using Calcium Phosphate Bone Substitutes in a Novel 3D Printed Four-Chamber Periosteal Bioreactor

Autologous bone replacement remains the preferred treatment for segmental defects of the mandible; however, it cannot replicate complex facial geometry and causes donor site morbidity. Bone tissue engineering has the potential to overcome these limitations. Various commercially available calcium phosphate-based bone substitutes (Novabone®, BioOss®, and Zengro®) are commonly used in dentistry for small bone defects around teeth and implants. However, their role in ectopic bone formation, which can later be applied as vascularized graft in a bone defect, is yet to be explored. Here, we compare the above-mentioned bone substitutes with autologous bone with the aim of selecting one for future studies of segmental mandibular repair. Six female sheep, aged 7-8 years, were implanted with 40 mm long four-chambered polyether ether ketone (PEEK) bioreactors prepared using additive manufacturing followed by plasma immersion ion implantation (PIII) to improve hydrophilicity and bioactivity. Each bioreactor was wrapped with vascularized scapular periosteum and the chambers were filled with autologous bone graft, Novabone®, BioOss®, and Zengro®, respectively. The bioreactors were implanted within a subscapular muscle pocket for either 8 weeks (two sheep), 10 weeks (two sheep), or 12 weeks (two sheep), after which they were removed and assessed by microCT and routine histology. Moderate bone formation was observed in autologous bone grafts, while low bone formation was observed in the BioOss® and Zengro® chambers. No bone formation was observed in the Novabone® chambers. Although the BioOss® and Zengro® chambers contained relatively small amounts of bone, endochondral ossification and retained hydroxyapatite suggest their potential in new bone formation in an ectopic site if a consistent supply of progenitor cells and/or growth factors can be ensured over a longer duration.

Bone regeneration in implant dentistry: Which are the factors affecting the clinical outcome?

The key factors that are needed for bone regeneration to take place include cells (osteoprogenitor and immune-inflammatory cells), a scaffold (blood clot) that facilitates the deposition of the bone matrix, signaling molecules, blood supply, and mechanical stability. However, even when these principles are met, the overall amount of regenerated bone, its stability over time and the incidence of complications may significantly vary. This manuscript provides a critical review on the main local and systemic factors that may have an impact on bone regeneration, trying to focus, whenever possible, on bone regeneration simultaneous to implant placement to treat bone dehiscence/fenestration defects or for bone contouring. In the future, it is likely that bone tissue engineering will change our approach to bone regeneration in implant dentistry by replacing the current biomaterials with osteoinductive scaffolds combined with cells and mechanical/soluble factors and by employing immunomodulatory materials that can both modulate the immune response and control other bone regeneration processes such as osteogenesis, osteoclastogenesis, or inflammation. However, there are currently important knowledge gaps on the biology of osseous formation and on the factors that can influence it that require further investigation. It is recommended that future studies should combine traditional clinical and radiographic assessments with non-invasive imaging and with patient-reported outcome measures. We also envisage that the integration of multi-omics approaches will help uncover the mechanisms responsible for the variability in regenerative outcomes observed in clinical practice.

Underestimated microbial infection of resorbable membranes on guided regeneration

Barrier membranes are critical in creating tissuecompartmentalization for guided tissue (GTR) and bone regeneration (GBR) therapies. More recently, resorbable membranes have been widely used for tissue and bone regeneration due to their improved properties and the dispensable re-entry surgery for membrane removal. However, in cases with membrane exposure, this may lead to microbial contamination that will compromise the integrity of the membrane, surrounding tissue, and bone regeneration, resulting in treatment failure. Although the microbial infection can negatively influence the clinical outcomes of regenerative therapy, such as GBR and GTR, there is a lack of clinical investigations in this field, especially concerning the microbial colonization of different types of membranes. Importantly, a deeper understanding of the mechanisms of biofilm growth and composition and pathogenesis on exposed membranes is still missing, explaining the mechanisms by which bone regeneration is reduced during membrane exposure. This scoping review comprehensively screened and discussed the current in vivo evidence and possible new perspectives on the microbial contamination of resorbable membranes. Results from eligible in vivo studies suggested that different bacterial species colonized exposed membranes according to their composition (collagen, expanded polytetrafluoroethylene (non-resorbable), and polylactic acid), but in all cases, it negatively affected the attachment level and amount of bone gain. However, limited models and techniques have evaluated the newly developed materials, and evidence is scarce. Finally, new approaches to enhance the antimicrobial effect should consider changing the membrane surface or incorporating long-term released antimicrobials in an effort to achieve better clinical success.

Evaluation of efficacy of non-resorbable membranes compared to resorbable membranes in patients undergoing guided bone regeneration

Background

Replacement of missing teeth in patients with prolonged edentulism poses a challenge for clinicians. An extended period of edentulism results in severe atrophy of alveolar ridges rendering them unsatisfactory for rehabilitation using an implant-supported prosthesis. To overcome this difficulty, Guided Bone Regeneration (GBR) was introduced and constructed upon the principles of Guided Tissue Regeneration (GTR) procedures. Evidence suggests that GBR has proven to be a predictable treatment modality for treating vertical and horizontal ridge deficiencies.

Objective

The present systematic review aimed to evaluate the efficacy of non-resorbable (N-RES) membranes compared to resorbable (RES) membranes in patients undergoing GBR.

Methods

An electronic search of three databases, including PubMed, Web of Science, and Scopus, was conducted for articles published until March 2022. A supplementary manual search of references from these articles was performed to include any articles that may have been overlooked in the electronic search. Articles that evaluated the efficacy of RES membranes and N-RES membranes in GBR were included. Case reports, case series, commentaries, letters to the editor, narrative or systematic reviews were excluded. Articles in languages other than English were also excluded. The articles were assessed against risk of bias 2 tool for Randomized Control Trials (RCTs) and ROBINS-I tool for Non-Randomized Clinical Trials (N-RCTs). The Grading of Recommendations Assessment, Development and Evaluation (GRADE) assessment was followed based on the Cochrane Handbook for quality assessment. A summary of findings table was used to present the results.

Results

One hundred and fifty one articles were identified in an electronic search. Eight articles met the inclusion criteria and were included in the present systematic review. The studies were conducted on partially or completely edentulous patients with alveolar ridge deficiencies undergoing vertical or horizontal bone for subsequent implant placement. The majority of the studies reported similar results for bone gain in both RES and N-RES membrane groups.

Conclusion

The available evidence suggests that RES and N-RES membranes are equally effective in GBR. However, the evidence must be interpreted with caution due to its 'low quality' GRADE assessment.

Clinical implications

Further research focusing on human clinical trials with well-matched subjects with homogeneity in the type and method of GBR and method of assessment of new bone formation will derive conclusive results on the efficacy of RES and N-RES membranes in achieving new bone formation.

Bone Regenerative Potential of Cross-Linked Collagen Membrane in Peri-Implant Osseous Defect: Case Series with Histologic/Micro-Computed Tomographic Findings

The role of a barrier membrane is crucial in guided bone regeneration (GBR) for space creation and cell occlusiveness. Those properties of the membrane should be sustained for a sufficient period. For such purpose, several cross-linked collagen membranes were introduced and demonstrated favorable clinical outcomes. However, histologic data were not sufficient to support the effect of cross-linked collagen membranes. In the present case series, healing after GBR using a cross-linked collagen membrane was investigated in-depth via histologic and micro-computed tomographic (micro-CT) analyses. 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide cross-linked collagen membrane was used in GBR for treating various peri-implant bone defects in seven patients. After 4-7 months of healing, newly formed tissue of hard consistency was observed over the implant platform. This tissue was carefully harvested and assessed. In micro-CT and histological analyses, evident new bone formation was revealed, especially in the vicinity of the collagen membrane. Moreover, it was histologically found that some newly formed bone was in intimate contact with the membrane. Although the exact mechanism of bone regeneration in the present cases was not clearly elucidated, the cross-linked collagen membrane appeared to contribute to ossification in GBR. Further studies are needed to confirm the findings of the present case series.

In Vitro Evaluation of the Permeability of Different Resorbable Xenogeneic Membranes after Collagenolytic Degradation

In this in vitro study, we compare the penetration of cells through different resorbable collagen membranes, which were collagenolytically degraded over different time periods. Three different resorbable collagen membranes were evaluated, including two non-cross-linked (NCL) membranes-namely, a porcine (NCL-P) and an equine (NCL-E) membrane-and an enzymatically cross-linked porcine (ECL-B) membrane. A special two-chamber model was fabricated, allowing for the placement of separating membranes, and a non-porous polyester membrane was used as a negative control (C), in order to verify the impermeability of the experimental chamber device. Round membrane samples with a diameter of 16 mm were fabricated. Eighteen membranes of each type were punched and placed on polyethylene nets as carriers. The membranes were then biodegraded-each on its carrier-in 12-well polystyrene plates: three samples of each membrane type were degraded for 1.5, 3, 6, or 12 h in 2 mL of a buffered collagenase solution, at 37 °C. For control purposes, three samples of each membrane type were not degraded, but only immersed in buffer solution for 1.5, 3, 6, or 12 h, at 37 °C. Another three samples of each type of membrane were degraded until complete dissolution, in order to determine the full hydroxyproline content for comparison. Liquid-preserved boar semen (containing at least 120 million sperm cells per milliliter) was used to test the cell occlusivity of the degraded membranes. At baseline and initial degradation, all tested membranes were tight, and no penetration was observed with up to 30 min of incubation time (results not shown). After 1.5 h, cells were partially capable of penetrating the NCL-E membrane only. One sample showed leakage, with a sperm volume of 1.7 million cells/mL over all samples. No penetration occurred in the test, NCL-P, and ECL-B groups. After a degradation time of 3 h, the NCL-P and ECL-B membranes remained occlusive to cells. All the membranes and measurements indicated leakage in the NCL-E group. After 6 h, four NCL-P measurements showed the first signs of cell penetration, as boar spermatozoa were detectable in the lower chamber (64 million cells/mL). The ECL-B membranes remained completely cell occlusive. After 12 h, four NCL-P measurements were cell penetration positive (14.6 million cells/mL), while the ECL-B group remained tight and showed no cell penetration. As the findings of our study are well in accordance with the results of several previous animal studies, it can be concluded that the surrogate model is capable of performing rapid and cheap screening of cell occlusivity for different collagen membranes in a very standardized manner. In particular, claims of long degradation resistance can be easily proven and compared. As the boar spermatozoa used in the present report had a size of 9 × 5 μm, smaller bacteria are probably also able to penetrate the leaking membranes; in this regard, our proposed study set-up may provide valuable information, although it must be acknowledged that sperm cells show active mobility and do not only translocate by growth.

Bone Regeneration by Multichannel Cylindrical Granular Bone Substitute for Regeneration of Bone in Cases of Tumor, Fracture, and Arthroplasty

In orthopedics, a number of synthetic bone substitutes are being used for the repair and regeneration of damaged or diseased bone. The nature of the bone substitutes determines the clinical outcome and its application for a range of orthopedic clinical conditions. In this study, we aimed to demonstrate the possible applications of multichannel granular bone substitutes in different types of orthopedic clinical conditions, including bone tumor, fracture, and bone defect with arthroplasty. A clinical investigation on a single patient for every specific type of disease was performed, and patient outcome was evaluated by physical and radiographic observation. Brief physical characterization of the granular bone substitute and in vivo animal model investigation were presented for a comprehensive understanding of the physical characteristics of the granules and of the performance of the bone substitute in a physiological environment, respectively. In all cases, the bone substitute stabilized the bone defect without any complications, and the defect regenerated slowly during the postoperative period. Gradual filling of the defect with the newly regenerated bone was confirmed by radiographic findings, and no adverse effects, such as osteolysis, graft dispersion, and non-union, were observed. Homogeneous bone formation was observed throughout the defect area, showing a three-dimensional bone regeneration. High-strength multichannel granules could be employed as versatile bone substitutes for the treatment of a wide range of orthopedic conditions.

Horizontal augmentation techniques in the mandible: a systematic review

Purpose

Placement of dental implants has evolved to be an advantageous treatment option for rehabilitation of the fully or partially edentulous mandible. In case of extensive horizontal bone resorption, the bone volume needs to be augmented prior to or during implant placement in order to obtain dental rehabilitation and maximize implant survival and success.

Methods

Our aim was to systematically review the available data on lateral augmentation techniques in the horizontally compromised mandible considering all grafting protocols using xenogeneic, synthetic, or allogeneic material. A computerized and manual literature search was performed for clinical studies (published January 1995 to March 2021).

Results

Eight studies ultimately met the inclusion criteria comprising a total of 276 procedures of xenogeneic, allogeneic, or autogenous bone graft applications in horizontal ridge defects. Particulate materials as well as bone blocks were used as grafts with a mean follow-up of 26.0 months across all included studies. Outcome measures, approaches and materials varied from study to study. A gain of horizontal bone width of the mandible with a mean of 4.8 mm was observed in seven of eight studies. All but one study, reported low bone graft failure rates of 4.4% in average.

Conclusions

Only limited data are available on the impact of different horizontal augmentation strategies in the mandible. The results show outcomes for xenogeneic as well as autologous bone materials for horizontal ridge augmentation of the lower jaw. The use of allogeneic bone-block grafts in combination with resorbable barrier membranes must be re-evaluated. Randomized controlled clinical trials are largely missing.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-022-00421-7.

The long-term impact of alveolar ridge preservation with xenograft bone mineral on peri-implant health after 5 years in function: A retrospective cohort study of 108 patients assessed clinically and radiologically

Objectives

When teeth are lost, dental implants contribute to improved oral function and quality of life. Limitations in dental implant placement arising from poor bone anatomy may be circumvented via alveolar ridge preservation (ARP). The aim is to evaluate the long‐term impact of ARP on peri‐implant health and the relationship with common risk indicators such as smoking and history of periodontitis.

Materials and Methods

One hundred and eight patients were enrolled in this retrospective cohort study with 308 implants. Of these, ∼41% were placed in bone sites that had previously received ARP with deproteinized bovine bone mineral xenograft. Association between baseline variables: ARP, age, gender, number of implants per patient, anatomical site, smoking, and previous history of grade III/IV periodontitis, and outcome variables: mucositis, peri‐implantitis, implant loss, full‐mouth plaque score (FMPS), full‐mouth bleeding score, and marginal bone loss (MBL) was evaluated using both univariate and multivariate models.

Results

After 5 years, the overall survival rate was 93.7%. The occurrence of peri‐implantitis was 21.3% and the extent of MBL was ~2.2 mm. Both peri‐implantitis occurrence and MBL were comparable between ARP⁺ and ARP⁻. Smoking is associated with higher FMPS and MBL.

Conclusions

The findings indicate that peri‐implant health can be maintained around dental implants for up to 5 years in ARP⁺ sites using Bio‐Oss®. Smoking is a major risk indicator for peri‐implantitis, whereas the association between history of periodontitis and the risk of peri‐implantitis, based on this specific, well‐maintained cohort and the specific implants used, remains inconclusive.

The Triangle Suture for Membrane Fixation in Guided Bone Regeneration Procedures: A Report of two Cases

INTRODUCTION

Existing evidence supports superior treatment outcomes in guided bone regeneration (GBR) procedures employing membrane fixation. The purpose of this report is to present a specific flap design and suturing method for stabilizing GBR barrier membranes.

CASE PRESENTATION

Two generally healthy patients received GBR using native collagen membranes stabilized with absorbable sutures. In both cases, we fixed barrier membranes apically using "triangle" sutures. Sling sutures (Case 1) or triangle sutures (Case 2) secured the crestal and palatal aspects of the membranes. No postoperative complications occurred, and both sites exhibited favorable alveolar ridge volume for implant placement.

CONCLUSIONS

The described triangle suture technique reliably stabilized GBR barrier membranes without the need for fixation hardware. Compared with suturing methods that limit graft volume and apply pressure over the grafted area, the triangle suture may offer clinical advantages.

Horizontal Augmentation of Chronic Mandibular Defects by the Guided Bone Regeneration Approach: A Randomized Study in Dogs

Various biomaterial combinations have been studied focusing on their ability to stabilize blood clots and maintain space under soft tissue to support new bone formation. A popular combination is Deproteinized Bovine Bone Mineral (DBBM) placed with a native collagen membrane (NCM) tacked to native bone. In this study, we compared the outcome of this treatment option to those achieved with three different graft/membrane combinations with respect to total newly occupied area and the mineralized compound inside. After bi-lateral extraction of two mandibular premolars in five adult beagles L-shaped alveolar defects were created. A total of 20 defects healed for 6 weeks resulting in chronic type bone defects. At baseline, four options were randomly allocated to five defects each: a. DBBM + NCM with a four-pin fixation across the ridge; b. DBBM + RCLC (ribose cross-linked collagen membrane); c. DBBM + NPPM (native porcine pericardium membrane); and d. Ca-sulfate (CS) + RCLC membrane. Membranes in b/c/d were not fixed; complete tensionless wound closure was achieved by CAF. Termination after 3 months and sampling followed, and non-decalcified processing and toluidine blue staining were applied. Microscopic images obtained at standardized magnification were histomorphometrically assessed by ImageJ software (NIH). An ANOVA post hoc test was applied; histomorphometric data are presented in this paper as medians and interquartile ranges (IRs). All sites healed uneventfully, all sites were sampled and block separation followed before Technovit embedding. Two central sections per block for each group were included. Two of five specimen were lost due to processing error and were excluded from group b. New bone area was significantly greater for option b. compared to a. (p = 0.001), c. (p = 0.002), and d. (p = 0.046). Residual non-bone graft area was significantly less for option d. compared to a. (p = 0.026) or c. (p = 0.021). We conclude that collagen membranes with a prolonged resorption/barrier profile combined with bone substitutes featuring different degradation profiles sufficiently support new bone formation. Tacking strategy/membrane fixation appears redundant when using these biomaterials.

Exposure of Barriers Used in GBR: Rate, Timing, Management, And Its Effect on Grafted Bone. A Retrospective Analysis

The purpose of this study is to compare exposure rate of three different barrier types after a guided-bone regenerationprocedure, as well as to compare the percentage grafted bone dimensional loss with and without exposed barriers. Patient records from September 2007 to May 2015 were reviewed to identify subjects that had received bone graft and then implant placement procedure after the graft is completely healed. The subjects were divided into 3 groups: 1) resorbable barrier 2) non-resorbable barrier, and 3) titanium-mesh barrier. Incidences of barrier exposure were recorded.  Cone-beam computed tomography images before treatment (T0), right after grafting (T1), and after healing (T2) were used to determine percentage grafted bone dimensional loss (%) and quantitative grafted bone remained (mm 2 ). Three cross-sectioned areas, at 1mm apart, of preplanned implant positions at the grafted site were measured on cone-beam computed tomography to calculate for grafted bone remained and grafted bone dimensional change. The exposure rate of all guided bone regeneration was 36.9%. Exposure rate of resorbable barrier (23.3%) is significantly lower than Titanium mesh (68.9%) and Non-resorbable (72.7%) (Chi-Square, P < .001).  The result from this study revealed that barrier types have significant effect on exposure rate. There was also a significant different in grafted bone dimensional loss in sites with barrier exposure (58.3%) and sites with no barrier exposure (44.1%) during the healing period (Mann-Whitney U, P = .008).

Comprehensive treatment for severe periodontitis with pathologic tooth migration-related bimaxillary protrusion: A case report with 3-year follow-up

BACKGROUND AND OVERVIEW

Patients with severe periodontitis often experience pathologic tooth migration (PTM), which impairs esthetics and leads to occlusal disharmony (for example, premature contacts and traumatic occlusion) that can further exacerbate periodontitis. The authors describe a patient who exhibited severe periodontitis with PTM-related bimaxillary protrusion. This report includes 3-year clinical outcomes after periodontal regenerative therapy, implant-anchored orthodontic therapy, and implant prosthodontics intended to achieve both functional and esthetic improvements.

CASE DESCRIPTION

A 63-year-old woman sought treatment with the chief complaint of maxillary anterior tooth mobility. Clinical examination revealed excessive tooth mobility, deep periodontal pockets, and infrabony defects in all teeth. All teeth exhibited PTM; the mandibular anterior teeth exhibited marked protrusion caused by the progression of periodontitis. After initial periodontal therapy, periodontal regenerative therapy was performed in all molar regions. At 6 and 9 months postoperatively, comprehensive orthodontic treatment was initiated for the mandible and maxilla, respectively, using orthodontic anchorage devices to achieve acceptable functional occlusion. After orthodontic treatment, staged guided bone regeneration was performed and dental implants were placed in the severely resorbed maxillary anterior ridge. This comprehensive treatment yielded favorable periodontal conditions, stable occlusion, and good esthetic outcomes.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Favorable esthetics, stable occlusion, and highly cleansable periodontal tissues were achieved with well-planned interdisciplinary and comprehensive treatment, although the patient had severe periodontitis and PTM-related bimaxillary protrusion.

Implants sites with concomitant bone regeneration using a resorbable or non-resorbable membrane result in stable marginal bone levels and similar profilometric outcomes over 5 years

OBJECTIVES

To assess clinical and radiographic outcomes as well as the profilometric contour alterations of peri-implant hard and soft tissues around single implants treated with simultaneous guided bone regeneration (GBR) at 5 years.

MATERIALS AND METHODS

Twenty-seven patients presenting with a single tooth gap in the esthetic zone received a two-piece implant. GBR was randomly performed using a resorbable (RES) or a non-resorbable membrane (N-RES) combined with a bone substitute material. Follow-up examinations were performed at baseline (BL = crown insertion), 1 year (FU-1), 3 years (FU-3), and at 5 years (FU-5) including clinical and radiographic parameters as well as profilometric changes. Statistics were performed by means of parametric and nonparametric tests.

RESULTS

At 5 years, 20 out of 27 patients (9 RES, 11 N-RES) were re-examined. Median values for probing depth changed insignificantly between BL and FU-5 in both groups. The median marginal bone levels were located 0.23 mm (0.06; 0.46; RES) and 0.17 mm (0.13;0.28; N-RES) below the implant shoulder at FU-5 (changes over time p < .05). The calculated median profilometric change between BL and FU-5 was -0.28 mm (-0.53;-0.20; RES; p = .016) and -0.24 mm (-0.43;0.08; N-RES; p = .102; intergroup p = .380). The horizontal bone thickness decreased significantly between re-entry and FU-5 for group RES at all measured levels (p < .05) measuring 0.87 mm (0.0; 2.05) at the implant shoulder, whereas the decrease for group N-RES was insignificant (p = .031) with 0 mm (0; 0.84) at the implant shoulder at 5 years.

CONCLUSIONS

Implants sites with concomitant GBR using a resorbable or non-resorbable membrane revealed stable marginal bone levels and clinical outcomes. Profilometric changes were clinically negligible over 5 years. The observed change in hard tissue thickness was partially compensated by an increase in soft tissue thickness.

Interventions for replacing missing teeth: alveolar ridge preservation techniques for dental implant site development

BACKGROUND

Alveolar bone changes following tooth extraction can compromise prosthodontic rehabilitation. Alveolar ridge preservation (ARP) has been proposed to limit these changes and improve prosthodontic and aesthetic outcomes when implants are used. This is an update of the Cochrane Review first published in 2015.

OBJECTIVES

To assess the clinical effects of various materials and techniques for ARP after tooth extraction compared with extraction alone or other methods of ARP, or both, in patients requiring dental implant placement following healing of extraction sockets.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 19 March 2021), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2021, Issue 2), MEDLINE Ovid (1946 to 19 March 2021), Embase Ovid (1980 to 19 March 2021), Latin American and Caribbean Health Science Information database (1982 to 19 March 2021), Web of Science Conference Proceedings (1990 to 19 March 2021), Scopus (1966 to 19 March 2021), ProQuest Dissertations and Theses (1861 to 19 March 2021), and OpenGrey (to 19 March 2021). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. A number of journals were also handsearched.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) on the use of ARP techniques with at least six months of follow-up. Outcome measures were: changes in the bucco-lingual/palatal width of alveolar ridge, changes in the vertical height of the alveolar ridge, complications, the need for additional augmentation prior to implant placement, aesthetic outcomes, implant failure rates, peri-implant marginal bone level changes, changes in probing depths and clinical attachment levels at teeth adjacent to the extraction site, and complications of future prosthodontic rehabilitation.

DATA COLLECTION AND ANALYSIS

We selected trials, extracted data, and assessed risk of bias in duplicate. Corresponding authors were contacted to obtain missing information. We estimated mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes, with 95% confidence intervals (95% CI). We constructed 'Summary of findings' tables to present the main findings and assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We included 16 RCTs conducted worldwide involving a total of 524 extraction sites in 426 adult participants. We assessed four trials as at overall high risk of bias and the remaining trials at unclear risk of bias. Nine new trials were included in this update with six new trials in the category of comparing ARP to extraction alone and three new trials in the category of comparing different grafting materials. ARP versus extraction: from the seven trials comparing xenografts with extraction alone, there is very low-certainty evidence of a reduction in loss of alveolar ridge width (MD -1.18 mm, 95% CI -1.82 to -0.54; P = 0.0003; 6 studies, 184 participants, 201 extraction sites), and height (MD -1.35 mm, 95% CI -2.00 to -0.70; P < 0.0001; 6 studies, 184 participants, 201 extraction sites) in favour of xenografts, but we found no evidence of a significant difference for the need for additional augmentation (RR 0.68, 95% CI 0.29 to 1.62; P = 0.39; 4 studies, 154 participants, 156 extraction sites; very low-certainty evidence) or in implant failure rate (RR 1.00, 95% CI 0.07 to 14.90; 2 studies, 70 participants/extraction sites; very low-certainty evidence). From the one trial comparing alloplasts versus extraction, there is very low-certainty evidence of a reduction in loss of alveolar ridge height (MD -3.73 mm; 95% CI -4.05 to -3.41; 1 study, 15 participants, 60 extraction sites) in favour of alloplasts. This single trial did not report any other outcomes. Different grafting materials for ARP: three trials (87 participants/extraction sites) compared allograft versus xenograft, two trials (37 participants, 55 extraction sites) compared alloplast versus xenograft, one trial (20 participants/extraction sites) compared alloplast with and without membrane, one trial (18 participants, 36 extraction sites) compared allograft with and without synthetic cell-binding peptide P-15, and one trial (30 participants/extraction sites) compared alloplast with different particle sizes. The evidence was of very low certainty for most comparisons and insufficient to determine whether there are clinically significant differences between different ARP techniques based on changes in alveolar ridge width and height, the need for additional augmentation prior to implant placement, or implant failure. We found no trials which evaluated parameters relating to clinical attachment levels, specific aesthetic or prosthodontic outcomes for any of the comparisons. No serious adverse events were reported with most trials indicating that the procedure was uneventful. Among the complications reported were delayed healing with partial exposure of the buccal plate at suture removal, postoperative pain and swelling, moderate glazing, redness and oedema, membrane exposure and partial loss of grafting material, and fibrous adhesions at the cervical part of previously preserved sockets, for the comparisons xenografts versus extraction, allografts versus xenografts, alloplasts versus xenografts, and alloplasts with and without membrane.

AUTHORS' CONCLUSIONS

ARP techniques may minimise the overall changes in residual ridge height and width six months after extraction but the evidence is very uncertain. There is lack of evidence of any differences in the need for additional augmentation at the time of implant placement, implant failure, aesthetic outcomes, or any other clinical parameters due to lack of information or long-term data. There is no evidence of any clinically significant difference between different grafting materials and barriers used for ARP. Further long-term RCTs that follow CONSORT guidelines (www.consort-statement.org) are necessary.

The Influence of Different Guided Bone Regeneration Procedures on the Contour of Bone Graft after Wound Closure: A Retrospective Cohort Study

The aim of this study was to evaluate the impact of different guided bone regeneration (GBR) procedures on bone graft contour after wound closure in lateral ridge augmentation. A total of 48 patients with 63 augmented sites were included in this study. Participants were divided into 4 groups (n = 12 in each group) based on different surgical procedures: group 1: particulate bone substitute + collagen membrane; group 2: particulate bone substitute + collagen membrane + healing cap, group 3: particulate bone substitute + injectable platelet-rich fibrin (i-PRF) + collagen membrane; group 4: particulate bone substitute + i-PRF + surgical template + collagen membrane. After wound closure, the thickness of labial graft was measured at 0–5 mm apical to the implant shoulder (T0–T5). At T0–T2, the thickness of labial graft in group 4 was significantly higher than the other three groups (p < 0.05). And group 4 showed significantly more labial graft thickness than group 1 and group 2 at T3–T5 (p < 0.05). Within the limitations of this study, the use of i-PRF in combination with the surgical template in GBR may contribute to achieving an appropriate bone graft contour after wound closure.

Radiographic changes in height and volume after lateral GBR procedures with different ratios of deproteinized bovine bone mineral and autogenous bone at different time points. An experimental study

OBJECTIVE

Estimate changes in augmentation height and volume after lateral guided bone regeneration (GBR) augmentation with different ratios of deproteinized bovine bone mineral (DBBM) and particulate autogenous bone (PAB) and autogenous bone block (ABB), at different time points.

MATERIAL AND METHODS

Twenty-four minipigs were randomly allocated into three healing periods. Lateral augmentation in 96 sites with standardized quantity of graft material was performed with different ratios of DBBM and PAB (50:50, 75:25, and 100:0) and ABB in combination with DBBM, covered by a collagen membrane. Changes in augmentation height and volume were assessed on CT volumes acquired 10, 20, and 30 weeks after surgery.

RESULTS

Reduction in bone augmentation height was as follows: 50:50-1.7 mm (-33.1%), 75:25-1.8 mm (-37.8%), 100:0-1.7 mm (-35.8%), and ABB - 0.2 mm (-3.7%), after 30 weeks. The augmentation height was significantly better preserved with ABB compared to 50:50, 75:25, and 100:0, while no significant difference was present among particulate grafts. No significant difference in volumetric reduction was found among 50:50, 75:25, 100:0 and ABB after 30 weeks, while 100:0 presented significant less reduction compared to 50:50, 75:25 and ABB after 10 and 20 weeks.

CONCLUSIONS

Augmentation height following GBR was better preserved with ABB covered with DBBM. Addition of PAB to DBBM did not affect the changes in height of the graft. The volumetric stability seems to be comparable for ABB covered by DBBM and all particulate grafts after 30 weeks. However, DBBM alone revealed significant less volume reduction in the early healing phase.

Clinical and histological sequelae of surgical complications in horizontal guided bone regeneration: a systematic review and proposal for management

It is not uncommon to encounter post-surgical complications after horizontal guided bone regeneration (GBR). The primary aim of this review was to evaluate the incidence and types of complications that occur after horizontal GBR and propose management strategies to deal with these clinical situations. A secondary aim was to conduct a histomorphometric review of the wound healing process at sites that experienced post-surgical complications after GBR. A keyword search of MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials for studies published in English from January 2015 to January 2020 was conducted for the primary aim and 23 studies were selected. A second search addressing the secondary aim was conducted, and five studies were included. Site-level analysis showed that the weighted mean incidence proportion of minor wound dehiscence and minor infections occurring at the augmented site was 9.9% [95% CI 6.4, 13.9, P < 0.01] and 1.5% [95% CI 0.4, 3.1, P = 0.21) respectively. Patient-level analysis showed minor and major complications occurring at a weighted mean incidence proportion of 16.1% [95% CI 11.9, 20.8, P = 0.01] and 1.6% [95% CI 0.0, 4.7, P < 0.01] respectively, while neurosensory alterations at the donor site was 7.0% [95% CI 1.3, 15.5, P < 0.01]. Subgroup analysis also revealed that the use of block grafts increased the incidence proportion of minor post-surgical complications, whereas a staged GBR procedure increased the incidence proportion of both minor and major post-surgical complications. Although exposure of the barrier membrane is often associated with less bone regeneration and graft resorption, the type of membrane used (resorbable or non-resorbable) had no statistically significant influence on any post-surgical complication. Histologically, a layer of fibrous connective tissue instead of bone is commonly observed at the interface between the native bone at the recipient site and the regenerated bone in cases with membrane exposure after GBR procedure. Minor wound dehiscence was the highest incidence proportion of post-surgical complications. Methods ranging from daily application of antiseptics, use of systemic antimicrobials, regular reviews, and total removal of the non-integrated biomaterials are commonly prescribed to manage these post-surgical complications in attempt to minimise the loss of tissue at the surgical site.

Horizontal ridge augmentation using native collagen membrane vs titanium mesh in atrophic maxillary ridges: Randomized clinical trial

BACKGROUND

Several techniques have been proposed to reconstruct deficient alveolar ridges including bone blocks, ridge splitting and guided bone regeneration (GBR). GBR has been successfully established in restoring horizontal bone deficiency. However, yet still there is a debate regarding the ideal barrier for GBR.

PURPOSE

To evaluate the quantity and the quality of the bone gained using collagen membrane with 1:1 mixture of autogenous and anoraganic bovine bone mineral compared to titanium mesh with the same mixture of bone for GBR of horizontally deficient maxillary ridges.

MATERIALS AND METHODS

Two different grafting techniques were evaluated, 10 patients receiving GBR using native collagen membrane using 1:1 autogenous and anorganic bovine bone mineral (ABBM) bone mixture, and 10 patients receiving GBR using titanium mesh with same mixture of bone.

RESULTS

Statistical analysis showed a significant increase in alveolar bone width in both techniques with a mean bone gain of 4.0 mm for Collagen group and 3.7 mm for titanium mesh group. Bone area percent was almost 28% for both groups. For Ti-mesh group, six sites soft tissue healing was uneventfully with no signs of wound dehiscence. However, four cases showed mesh exposure first 3 patients showed this exposure 3 weeks postoperatively while the fourth patient showed exposure 4 months postoperatively. The mean graft resorption in the Collagen and mesh group 6 months postoperative was considered nonsignificant.

CONCLUSIONS

GBR with both collagen membrane and titanium mesh using a 1:1 mixture of autogenous and ABBM is a viable technique for horizontal augmentation of deficient maxillary alveolar ridges. Titanium mesh is a more technique sensitive compared to collagen membrane. Soft tissue dehiscence and difficulty during second stage removal should limit its use in augmentation of horizontally deficient maxillary ridges.

Influence of wound closure on volume stability with the application of different GBR materials: an in vitro cone-beam computed tomographic study

Purpose

To assess the influence of using different combinations of guided bone regeneration (GBR) materials on volume changes after wound closure at peri-implant dehiscence defects.

Methods

In 5 pig mandibles, standardized bone defects were created and implants were centrally placed. The defects were augmented using different combinations of GBR materials: xenogeneic granulate and collagen membrane (group 1, n=10), xenogeneic granulate and alloplastic membrane (group 2, n=10), alloplastic granulates and alloplastic membrane (group 3, n=10). The horizontal thickness was assessed using cone-beam computed tomography before and after suturing. Measurements were performed at the implant shoulder (HT0) and at 1 mm (HT1) and 2 mm (HT2) below. The data were statistically analysed using the Wilcoxon signed-rank test to evaluate within-group differences. Bonferroni correction was applied when calculating statistical significance between the groups.

Results

The mean horizontal thickness before suturing was 2.55±0.53 mm (group 1), 1.94±0.56 mm (group 2), and 2.49±0.73 mm (group 3). Post-suturing, the values were 1.47±0.31 mm (group 1), 1.77±0.27 mm (group 2), and 2.00±0.48 mm (group 3). All groups demonstrated a loss of horizontal dimension. Intragroup changes exhibited significant differences in group 1 (P<0.001) and group 3 (P<0.01). Intergroup comparisons revealed statistically significant differences of the relative changes between groups 1 and 2 (P=0.033) and groups 1 and 3 (P=0.015).

Conclusions

Volume change after wound closure was minimized by using an alloplastic membrane. The stability of the augmented horizontal thickness was most ensured by using this type of membrane irrespective of the bone substitute material used for membrane support.

Effect of membrane exposure on guided bone regeneration: A systematic review and meta-analysis

AIMS

This review aimed at investigating the effect of membrane exposure on guided bone regeneration (GBR) outcomes at peri-implant sites and edentulous ridges.

MATERIAL AND METHODS

Electronic and manual literature searches were conducted by two independent reviewers using four databases, including MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials, for articles up to February 2017. Articles were included if they were human clinical trials or case series reporting outcomes of GBR procedures with and without membrane exposure. A random-effects meta-analysis was conducted, and the weighted mean difference (WMD) between the two groups and 95% confidence interval (CI) were reported.

RESULTS

Overall, eight articles were included in the quantitative analysis. The WMD of the horizontal bone gain at edentulous ridges was -76.24% (95% CI = -137.52% to -14.97%, p = .01) between sites with membrane exposure and without exposure. In addition, the WMD of the dehiscence reduction at peri-implant sites was -27.27% (95% CI of -45.87% to -8.68%, p = .004). Both analyses showed significantly favorable outcomes at the sites without membrane exposure.

CONCLUSION

Based on the findings of this study, membrane exposure after GBR procedures has a significant detrimental influence on the outcome of bone augmentation. For the edentulous ridges, the sites without membrane exposure achieved 74% more horizontal bone gain than the sites with exposure. For peri-implant dehiscence defects, the sites without membrane exposure had 27% more defect reduction than the sites with exposure.

Sugar-based collagen membrane cross-linking increases barrier capacity of membranes

OBJECTIVES

This study examines the permeability and barrier capacity of a sugar cross-linked resorbable collagen membrane ex vivo and in vivo.

MATERIALS AND METHODS

In an ex vivo study, injectable platelet-rich fibrin (i-PRF), a peripheral blood-derived human leukocyte-and-platelet-rich plasma was used to analyze membrane permeability. in vivo subcutaneous implantation in Wistar rats (n = 4 per time point and group) was used to investigate the barrier capacity of the membrane. The induced in vivo cellular reaction was evaluated at 3, 15, and 30 days and compared to sham OP (control) without biomaterial using histological, immunohistochemical, and histomorphometric methods.

RESULTS

Ex vivo, the membrane was impenetrable to leukocytes, platelets, and fibrin from peripheral human blood concentrate (PRF). In vivo, the membrane maintained its structure and remained impervious to cells, connective tissue, and vessels over 30 days. CD-68-positive cell (macrophage) numbers significantly decreased from 3 to 15 days, while from day 15 onwards, the number of multinucleated giant cells (MNGCs) increased significantly. Correspondingly, a rise in implantation bed vascularization from 15 to 30 days was observed. However, no signs of degradation or material breakdown were observed at any time point.

CONCLUSION

Ex vivo and in vivo results showed material impermeability to cellular infiltration of human and murine cells, which highlights the membrane capacity to serve as a barrier over 30 days. However, whether the induced MNGCs will lead to material degradation or encapsulation over the long term requires further investigation.

CLINICAL RELEVANCE

The data presented are of great clinical interest, as they contribute to the ongoing discussion concerning to what extent an implanted material should be integrated versus serving only as a barrier membrane.

Histomorphometric analyses of area fraction of different ratios of Bio-Oss® and bone prior to grafting procedures - An in vitro study to demonstrate a baseline

OBJECTIVE

The objective of this study was to estimate the area fraction of different ratios of Bio-Oss^® and bone, prior to grafting in an in vitro model to demonstrate a histomorphometric baseline.

METHODS

Bio-Oss^® particles were mixed with autogenous bone from pig jaw in three different ratios (50:50, 80:20 and 100:0) and packed in rice paper in a standardized procedure. Histomorphometric analyses were performed in 25 specimens and 74 regions of interest. The area percentage of Bio-Oss^® , bone, and non-mineralized tissue (NMT) were calculated. Results were reported as mean values and 95% confidence interval (CI).

RESULTS

The mean area fraction of Bio-Oss^® was 20.6% (CI: 18.2-23) in the 50:50 mixture, 33.6% (CI: 29.7-37.6) in the 80:20 mixture, and 43.4% (CI: 40.5-46.3) in the 100:0 mixture. The mean area fraction of NMT was 60.5% (CI: 57.9-63.1) in the 50:50 mixture, 59.6% (CI: 56.4-62.7) in the 80:20 mixture, and 56.6% (CI: 53.7-59.5) in the 100:0 mixture. The mean area fraction of bone was 18.9% (CI: 16.9-20.9) in the 50:50 mixture and 6.8% (CI: 5-8.6) in the 80:20 mixture.

CONCLUSION

There is a great difference in the clinically estimated percentage and the histomorphometrically evaluated percentage of Bio-Oss^® at baseline, prior to grafting. The area fraction of different tissues presented in this study may be beneficial as guidance for histomorphometrical baseline calculations when different mixtures of Bio-Oss^® and autogenous bone are used as grafting materials.

Lateral ridge augmentation with Bio-Oss alone or Bio-Oss mixed with particulate autogenous bone graft: a systematic review

The objective of this systematic review was to test the hypothesis of no difference in implant treatment outcomes when using Bio-Oss alone or Bio-Oss mixed with particulate autogenous bone grafts for lateral ridge augmentation. A search of the MEDLINE, Cochrane Library, and Embase databases in combination with a hand-search of relevant journals was conducted. Human studies published in English from 1 January 1990 to 1 May 2016 were included. The search provided 337 titles and six studies fulfilled the inclusion criteria. Considerable variation prevented a meta-analysis from being performed. The two treatment modalities have never been compared within the same study. Non-comparative studies demonstrated a 3-year implant survival of 96% with 50% Bio-Oss mixed with 50% autogenous bone graft. Moreover, Bio-Oss alone or Bio-Oss mixed with autogenous bone graft seems to increase the amount of newly formed bone as well as the width of the alveolar process. Within the limitations of this systematic review, lateral ridge augmentation with Bio-Oss alone or in combination with autogenous bone graft seems to induce newly formed bone and increase the width of the alveolar process, with high short-term implant survival. However, long-term studies comparing the two treatment modalities are needed before final conclusions can be drawn.

The Role of Two Different Collagen Membranes for Dehiscence Defect Around Implants in Humans

The aim of this study was to elucidate the role of 2 types of collagen membranes (cross-linked vs noncross-linked) used in conjunction with autogenous or allogenic bone followed by xenogeneic bone particles for dehiscence defect around implants in humans. Experimental groups were divided into 2 groups: Group CL (cross-linked, Ossix Plus, n = 24 implants, 16 patients) and Group NCL (noncross-linked, Bio-Gide, n = 25 implants, 18 patients). At the time of implant insertion and uncovery surgery, measurements of the dehiscence bony height, width, and surface area were made. Before applying the membrane to defects, guided bone regeneration was performed. Because it is difficult to measure the degree of exposure, early exposed cases were excluded from the result analysis. The mean percentage gain of the dehiscence defect and the mean marginal bone reduction value of follow-up radiograph did not show statistically significant differences between the 2 groups. Both membranes exhibited satisfactory results on dehiscence defects. As a result, our authors concluded the success of guided bone regeneration was performed simultaneously for dehiscence defects around the implant, regardless whether collagen membranes were cross-linked or noncross-linked.

Interventions for replacing missing teeth: alveolar ridge preservation techniques for dental implant site development

BACKGROUND

Alveolar bone changes following tooth extraction can compromise prosthodontic rehabilitation. Alveolar ridge preservation (ARP) has been proposed to limit these changes and improve prosthodontic and aesthetic outcomes when implants are used.

OBJECTIVES

To assess the clinical effects of various materials and techniques for ARP after tooth extraction compared with extraction alone or other methods of ARP, or both, in patients requiring dental implant placement following healing of extraction sockets.

SEARCH METHODS

The following electronic databases were searched: the Cochrane Oral Health Group's Trials Register (to 22 July 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2014, Issue 6), MEDLINE via OVID (1946 to 22 July 2014), EMBASE via OVID (1980 to 22 July 2014), LILACS via BIREME (1982 to 22 July 2014), the Meta Register of Current Controlled Trials (to 22 July 2014), ClinicalTrials.gov (to 22 July 2014), the World Health Organization International Clinical Trials Registry Platform (to 22 July 2014), Web of Science Conference Proceedings (1990 to 22 July 2014), Scopus (1966 to 22 July 2014), ProQuest Dissertations and Theses (1861 to 22 July 2014) and OpenGrey (to 22 July 2014). A number of journals were also handsearched. Trial authors were contacted to identify unpublished randomised controlled trials. There were no restrictions regarding language and date of publication in the searches of the electronic databases.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) on the use of alveolar ridge preservation techniques with at least six months of follow-up. Outcome measures were: changes in the bucco-lingual/palatal width of alveolar ridge, changes in the vertical height of the alveolar ridge, complications, the need for additional augmentation prior to implant placement, aesthetic outcomes, implant failure rates, peri-implant marginal bone level changes, changes in probing depths and clinical attachment levels at teeth adjacent to the extraction site, and complications of future prosthodontic rehabilitation.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently and assessed risk of bias for each included trial. Corresponding authors were contacted to obtain missing information. Results were combined using random-effects models with mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes, with 95% confidence intervals (95% CI). We constructed 'Summary of findings' tables to present the main findings.

MAIN RESULTS

A total of 50 trials were potentially eligible for inclusion, of which 42 trials were excluded. We included eight RCTs with a total of 233 extraction sites in 184 participants. One trial was judged to be at unclear risk of bias and the remaining trials were at high risk of bias. From two trials comparing xenograft with extraction alone (70 participants, moderate quality evidence), there was some evidence of a reduction in loss of alveolar ridge height (MD -2.60 mm; 95% CI -3.43 to -1.76) and width (MD -1.97 mm; 95% CI -2.48 to -1.46). This was also found in one trial comparing allograft with extraction (24 participants, low quality evidence): ridge height (MD -2.20 mm; 95% CI -0.75 to -3.65) and width (MD - 1.40 mm; 95% CI 0.00 to -2.80) and height. From two RCTs comparing alloplast versus xenograft no evidence was found that either ridge preservation technique caused a smaller reduction in loss of ridge height (MD -0.35 mm; 95% CI -0.86 to 0.16) or width (MD -0.44 mm; 95% CI -0.90 to 0.02; two trials (55 participants); moderate quality evidence). There was insufficient evidence to determine whether there are clinically significant differences between different ARP techniques and extraction based on the need for additional augmentation prior to implant placement, complications, implant failure, or changes in peri-implant marginal bone levels and probing depths of neighbouring teeth. We found no trials which evaluated parameters relating to clinical attachment levels, specific aesthetic or prosthodontic outcomes.

AUTHORS' CONCLUSIONS

There is limited evidence that ARP techniques may minimise the overall changes in residual ridge height and width six months after extraction. There is also lack of evidence of any differences in implant failure, aesthetic outcomes or any other clinical parameters due to the lack of information or long-term data. There is no convincing evidence of any clinically significant difference between different grafting materials and barriers used for ARP. Further long term RCTs that follow CONSORT guidelines (www.consort-statement.org) are necessary.

Receptor activator of NF-kappaB ligand (RANKL) and CD 31 expressions in chronic periodontitis patients before and after surgery

Aim of the study

The present study investigated the hypothesis that upregulation of receptor activator of NF-kappaB ligand (RANKL) expression may be associated with upregulation of endothelial cell activitiy, which is common for periods of periodontal bone loss in chronic periodontitis.

Material and methods

RANKL expression of activated cells in soft tissue biopsies with CD 31 activity and the presence of RANKL and osteoprotegerin (OPG) in gingival crevicular fluid (GCF) were assessed in chronic periodontitis patients. Biopsies from 17 patients and 10 healthy subjects were immunohistochemically analyzed. Clinical measurements [plaque index (PI), the gingival index (GI), probing pocket depth (PPD), clinical attachment level (CAL) and gingival bleeding index (GBI)] and GCF samples were obtained before and after periodontal therapy.

Results

CD31 staining did not support the assumption that endothelium-like cells were predominantly associated with RANKL expression.

Conclusions

RANKL-positive cells were widely distributed in periodontitis patients giving only partial support to the hypothesis that RANKL expression is restricted to T- and B-cell activation.

Platelet-rich plasma-assisted guided bone regeneration for ridge augmentation: a randomized, controlled clinical trial

BACKGROUND

Platelet-rich plasma (PRP) contains a number of biologically active growth factors, and previous studies have reported conflicting ridge augmentation results. The primary aim of this randomized, controlled, masked, clinical trial was to determine if PRP combined with a rapidly resorbing cancellous allograft would enhance the regenerative result compared with an allograft without PRP.

METHODS

Thirty-two patients with an edentulous ridge defect were sequentially entered into the study; four were excluded from data analysis. Fourteen patients received a cancellous allograft (CAN group) and the other 14 received a cancellous allograft mixed with PRP (PRP group). All 28 grafted sites were covered with a resorbable polylactide membrane. After elevation of a full-thickness flap, horizontal ridge dimensions were measured with a digital caliper at the crest and 5 mm apical to the crest. Vertical ridge dimensions were measured from a tooth-supported stent. All sites were reentered at 4 months, and a trephine core was obtained for histologic analysis before implant placement.

RESULTS

The crestal ridge width for the CAN group had a mean gain of 2.0 ± 1.2 mm, whereas the PRP group gained 2.9 ± 1.0, and the difference was statistically significant between groups (P <0.05). The percent vital bone was 36% ± 14% for the CAN group compared with 51% ± 15% for the PRP group and was statistically significant between groups (P <0.05). Loss of augmented ridge width was 34% ± 17% for the CAN group and 28% ± 17% for the PRP group (P >0.05).

CONCLUSION

These clinical and histologic findings suggest that PRP enhanced bone regeneration and resulted in increased horizontal bone gain and percentage vital bone.

Surgical Approaches Based on Biological Objectives: GTR versus GBR Techniques

Guided tissue regenerative (GTR) therapies are performed to regenerate the previously lost tooth supporting structure, thus maintaining the aesthetics and masticatory function of the available dentition. Alveolar ridge augmentation procedures (GBR) intend to regain the alveolar bone lost following tooth extraction and/or periodontal disease. Several biomaterials and surgical approaches have been proposed. In this paper we report biomaterials and surgical techniques used for periodontal and bone regenerative procedures. Particular attention will be adopted to highlight the biological basis for the different therapeutic approaches.

Influence of a collagen membrane and recombinant platelet-derived growth factor on vertical bone augmentation in implant-fixed deproteinized bovine bone--animal pilot study

OBJECTIVES

Combinations of bone substitute block materials with membrane techniques as well as with growth factors are possible options to enhance the prognosis of vertical bone augmentation. Therefore, the aim of the pilot study was to compare the influence of a collagen membrane and a signal protein (rhPDGF-BB) on vertical bone augmentation with a stable fixed block material (deproteinized bovine bone [DBB]).

MATERIALS AND METHODS

In 12 rabbits, a DBB-block was implant-fixed on the tibia in a split-leg-design. Included were: DBB only (control), DBB + collagen membrane (test), DBB + rhPDGF-BB (test) and DBB + rhPDGF-BB + collagen membrane (test). 24 samples were examined after 3 (n = 12) and 6 weeks (n = 12). Calculated parameters were new bone area (NBA;%), new vertical bone height (VBH; mm). Due to the pilot character of this study, single values are shown descriptively only.

RESULTS

After 3 weeks, there were constant higher NBA values in the rhPDGF-BB-group without membrane (NBA (%) DBB: 30/16/4; DBB + membrane: 25/17/7, DBB + rhPDGF-BB: 40/33/34, DBB + rhPDGF-BB + membrane: 0/30/16; VBH (mm) DBB: 1.2/1.2/1, DBB + membrane: 0.7/0.9/1, DBB + rhPDGF-BB: 0.7/0.9/1, DBB + rhPDGF-BB + membrane: 0/1.1/1). After 6 weeks, both membrane groups showed a constant higher NBA and VBH independent to the use of rhPDGF-BB (NBA DBB: 3/0/5, DBB + membrane: 20/35/31, DBB + rhPDGF-BB: 5/8/4, DBB + rhPDGF-BB + membrane: 31/35/40; VBH DBB: 0.3/0.3/0.6, DBB + membrane: 1.6/2.4/2.1, DBB + rhPDGF-BB: 0.4/0.7/0.8, DBB + rhPDGF-BB + membrane: 1.8/2/1.8).

CONCLUSIONS

For vertical augmentation, the addition of rhPDGF-BB to DBB-blocks may increase early bone growth. In the later phase, the use of a collagen membrane enhances new bone volume and height to a significant greater extend. Even if the results are higher than those in the non-membrane groups, the low gain of bone after the short time periods still needs improvement.

A liquid membrane as a barrier membrane for guided bone regeneration

Membranes made of several different materials are available in the market, nonresorbable (e.g. ePTFE), resorbable (e.g. synthetic or collagen) and liguid applicable (e.g. Polyethylene glycol or Atrisorb). The purpose of the present study was to evaluate whether or not in situ application of Atrisorb could be used as a barrier membrane for guided bone regeneration. Ten patients with insufficient alveolar ridge width for implant placement participated in the study. Atrisorb in conjunction with various bone grafts was used to treat 10 different sites, 3 sites treated prior to implant placement and 7 sites in conjunction with implant placement. Augmented sites were allowed to heal for 3 to 7 months, with mean healing time of 4.7 months. Healing was uneventful with no major complications. Two sites experienced a flap dehiscence accompanied by barrier exposure during the initial healing period. Secondary healing was achieved soon after with no signs of infection, giving Atrisorb a barrier exposure rate of 20% for the present study, which corresponds to favorably to that of resorbable membranes. The liquid membrane has the potential of being a viable alternative to traditional resorbable membranes for use in GBR procedures.

An interdisciplinary treatment approach combining orthodontic forced eruption with immediate implant placement to achieve a satisfactory treatment outcome: a case report

BACKGROUND

Periodontal disease often results in severely bony defects around the teeth and leads to eventual extraction. Remaining bone morphology often compromises ideally restoration-driven positions and deteriorates the success rates for dental implants.

PURPOSE

The present investigation illustrates the clinical outcome of immediately installing an implant following orthodontic forced eruption and atraumatic extraction.

MATERIAL AND METHODS

The subject of this study is a 40-year-old Asian female with a right mandibular first molar that had a deep probing depth on the mesial side and mobility. Via the aid of radiographic examination, the tooth that had an angular bony defect and apical lesion was diagnosed as having deep caries and chronic periodontitis with a poor prognosis. After consultation with the patient, we developed a treatment plan incorporating a forced eruption with immediate implantation, intended to augment the alveolar bone volume and increase the width of keratinized gingivae, in a nonsurgical manner.

RESULTS

Following 12 months of orthodontic treatment, the tooth was successfully moved occlusally in conjunction with an 8 mm vertical interdental bone augmentation. Because of sufficient volume of bone and satisfactory gingival dimensions, the implant showed adequate initial stability in the correct position to facilitate physiological and aesthetic prerequisites. After 6 months of osteointegration, a customized impression coping was utilized to transfer the established emergence profile to a definitive cast for the fabrication of a customized abutment. The final prosthesis was made using a customized metal abutment and ceramometal crown.

CONCLUSION

In the face of difficult clinical challenges, meticulous inspection and a comprehensive treatment plan were crucial. Interdisciplinary treatment through the careful integration of multiple specialists suggests the possibility of optimal results with high predictability.

Randomized controlled trial on lateral augmentation using two collagen membranes: morphometric results on mineralized tissue compound

BACKGROUND

Guided bone regeneration is considered an effective tool for gaining mineralized tissue either at exposed implant surface or in deficient alveolar ridge areas before implant placement.

MATERIAL AND METHODS

Customized casts obtained following impression taking at surgery and re-entry allowed for morphometric assessment of alveolar ridge alterations 6 months after one-stage augmentation of bone dehiscences. In a randomized pilot study using biphasic calcium phosphate tests (n=17) received treatment with ribose cross-linked collagen membranes (RCLM), whereas controls (n=20) received non-cross-linked membranes. The primary endpoint was to quantify the effect of membrane type on dimensional changes in bone margins at crestal level of endosseous implants.

RESULTS

Soft tissue dehiscencies occurred at 70.5% and 55% frequency for tests and controls, respectively. Gain in clinically hard newly mineralized tissue at the crestal level was significantly higher in test group in lateral (1.8 versus 0.7 mm; p=.046) and in vertical dimensions (1.1 versus 0.2 mm; p=.035) compared with controls. Second measurement obtained at the border of reflected flap revealed no significant difference between groups (3.0 versus 2.1 mm; p=0.57) for lateral dimension.

CONCLUSIONS

Both collagen devices were effective in bone augmentation. RCLMs supported mineralization process and remodelling even in sites showing compromised healing as indicated by morphometric outcome.