Guided bone regeneration for dehiscence and fenestration defects on implants using an absorbable polymer barrier

Effect of lateral bone augmentation procedures in correcting peri-implant bone dehiscence and fenestration defects: A systematic review and network meta-analysis

Purpose

The aim of the present systematic review was to evaluate the effect of different lateral bone augmentation (LBA) procedures on the complete correction of a peri‐implant bone dehiscence (BD) or fenestration (BF) from implant placement to implant surgical uncovering.

Methods

Electronic (Medline, Scopus, and Cochrane databases) and hand literature searches were performed for studies including at least one treatment arm where any LBA had been applied to correct a BD/BF at implant placement (T0). Studies where BD/BF was left untreated were also retrieved as negative control. Data from 24 selected articles were used to perform a network meta‐analysis. Based on the proportion of nonresolved BD/BF at implant surgical uncovering (T1), a hierarchy of LBA procedures, and was determined. Spontaneous healing (i.e., exposed implant surface covered by a full‐thickness flap; SELF) was also included in the hierarchy. Resorbable membrane + bone graft (RM + BG) was used as reference group. An analysis on the effect of nonhuman (NHBS) vs human (HBS) derived bone substitutes was also performed. NHBS was used as the reference group.

Results

No statistically significant differences were found among treatments for the proportion of nonresolved BD/BF. SELF performed substantially worse compared to RM + BG (OR: 5.78 × 10, CI: 4.83 × 10 – 1.3 × 10⁸⁶). Treatment based on a combination of a graft material and membrane/periosteum appeared to perform slightly better than treatments using graft material or membrane alone. NHBS appeared to perform better than HBS.

SELF had the worst effect among all treatments for both BD/BF height reduction (BDH) and BD/BF width reduction (BDW). Nonresorbable membrane (NRM) and patient's own periosteum (PERI) + BG showed greater increases in buccal bone thickness than RM + BG.

Conclusion

Reconstructive treatment (including use of graft alone, membrane alone, or combinations of grafts and either membrane or patient's own periosteum) of a BD/BF at implant placement favorably and significantly impacts on the probability to obtain complete correction of the BD/BF at implant uncovering when compared to full‐thickness flap repositioning on the BD/BF. When using a bone substitute, a nonhuman derived one may be suggested.

Healing Process with the use of a New Resorbable Synthetic Membrane

Background:

Currently, absorbable membranes tend to be used most frequently for guided bone regeneration. They have many advantages and the most commonly reported complication is early exposure.

Objective:

This retrospective study reports the healing process of soft tissues over a four-week period using synthetic absorbable membranes.

Study Design:

One-hundred and ten cases were included. Soft tissue healing was assessed from anonymized photographs, in accordance with the criteria of the Early Healing Index (EHI) (Watchel et al., 2003). Cohen's Kappa (K) test was used to estimate the reliability of the measures and the variability between the examiners. Chi-squared test and Fisher’s exact test were used to assess the combination of healing outcomes with respect to the type of surgical intervention.

Results:

At 1-week, 81% of the cases showed a Primary Closure (PC) when the membrane was not initially exposed. The score increased to 98% at 4-weeks. Healing at 1-week varied significantly according to the type of intervention, with 73% of primary closure for bone augmentation during implantation, versus 60% for bone augmentation before implantation and 46% for alveolar preservation (Chi-square test, p = 0.049). No statistically significant differences in the healing process were observed between the smoking and non-smoking groups.

Conclusion:

This clinical study shows that the safety and exposure rates of this new synthetic membrane are comparable to the data gathered in the literature concerning non-cross-linked collagenous membranes.

Clinical and histological evaluations of alveolar ridge augmentation using a novel bi-layered porous polyethylene barrier membrane

Guided bone regeneration (GBR) is an effective alveolar ridge reconstruction technique used before or at implant placement. The combination of various barrier membranes and bone substitutes has been employed. This study aimed to perform a preliminarily evaluation of the safety and performance of a new nonabsorbable bi-layered porous polyethylene (PPE) membrane, in combination with a freeze-dried cortical bone allograft in posterior mandibular ridge augmentation. Fifteen adults who had combined posterior mandibular defects were included for ridge augmentation via GBR using PPE membrane and allograft before implant placement. The keratinized mucosa width (KW), ridge width (RW), ridge height (RH), distance from measurement matrix to bone (DMB), and horizontal alveolar width at 14.0 mm apical to the occlusal plane (HAW) were clinically measured at 15 intended implant sites before and after the augmentation. Fifteen biopsy specimens were harvested at the implant sites for histological analysis. All the subjects completed the whole study. The KW and RH showed minor gains by 0.2 ± 1.4 mm and 0.9 ± 2.3 mm respectively; however, no statistically significant differences were found between, before, and after the augmentation (P > 0.05). In contrast, the RW and HAW significantly increased by 4.8 ± 1.6 mm and 2.3 ± 1.7 mm, respectively, (P ≤ 0.001), while DMB significantly decreased by 1.0 ± 0.8 mm after treatment (P < 0.001). Histological analysis revealed that allograft underwent active bone remodeling. The PPE membrane was adequately safe and efficient to use with allograft in GBR for the reconstruction of combined ridge defects. Although some complications were observed, these were manageable and subsequently lead to successful implant placement for all the subjects. However, further randomized controlled trials are still needed to confirm these findings.

Compound-Droplet-Pairs-Filled Hydrogel Microfiber for Electric-Field-Induced Selective Release

The separate co-encapsulation and selective controlled release of multiple encapsulants in a predetermined sequence has potentially important applications for drug delivery and tissue engineering. However, the selective controlled release of distinct contents upon one triggering event for most existing microcarriers still remains challenging. Here, novel microfluidic fabrication of compound-droplet-pairs-filled hydrogel microfibers (C-Fibers) is presented for two-step selective controlled release under AC electric field. The parallel arranged compound droplets enable the separate co-encapsulation of distinct contents in a single microfiber, and the release sequence is guaranteed by the discrepancy of the shell thickness or core conductivity of the encapsulated droplets. This is demonstrated by using a high-frequency electric field to trigger the first burst release of droplets with higher conductivity or thinner shell, followed by the second release of the other droplets under low-frequency electric field. The reported C-Fibers provide novel multidelivery system for a wide range of applications that require controlled release of multiple ingredients in a prescribed sequence.

The Use of Poly-d,l-lactic Acid (PDLLA) Devices for Bone Augmentation Techniques: A Systematic Review

Poly-d,l-lactic acid (PDLLA) has been proposed in dentistry for regenerative procedures in the form of membranes, screws, and pins. The aim of this review was to evaluate the efficacy of bone augmentation techniques using PDLLA devices. A literature search was carried out by two independent and calibrated reviewers. All interventional and observational studies assessing the efficacy of bone augmentation techniques using PDLLA devices were included. Six studies were included. The relevant variability of design and methods impeded any qualitative or quantitative comparison. Ease of handling, absence of a re-entry phase, moldability of foils, and good soft-tissue response were appreciated characteristics of PDLLA devices. Some drawbacks such as the risk of membrane exposition, a prolonged adsorbability, and a tendency to a fibrous encapsulation of the PDLLA devices have been described, although the clinical significance of these findings is unclear. Clinical data about PDLLA devices for bone regeneration are very scarce and heterogenous. Well-designed randomized controlled trials comparing the use of PDLLA foils and pins with conventional membranes for bone regeneration are strongly encouraged in order to understand the real clinical benefits/drawbacks of this technique.

Guided Tissue Regeneration in Four Teeth Using a Liquid Polymer Membrane

Periodontal disease is one of the most common diseases diagnosed in dogs and cats. Guided tissue regeneration (GTR) is a treatment alternative to extraction of strategically important teeth. The barrier membrane used in the GTR procedure is of key importance. The purpose of this case series was to evaluate a liquid polymer gel as a membrane for GTR. The polymer gel ( N-methyl-2-pyrrolidone and poly [DL-lactide]) combined with 8.5% doxycycline hyclate was used in place of a traditional membrane in 4 teeth. The teeth were re-examined 6 months postoperatively for radiographic evaluation. A decrease in probing depth and new alveolar bone formation was seen 6 months postoperatively. Improvement in periodontal disease stage was seen in 2 of the 4 teeth. Larger controlled trials with histopathologic evaluation are indicated to further assess the use of this polymer as a membrane in GTR. However, the clinical outcomes of all 4 treated teeth were considered successful.

Biocompatibility, resorption and biofunctionality of a new synthetic biodegradable membrane for guided bone regeneration

Membranes for guided bone regeneration (GBR) were prepared from the synthetic biodegradable polymer poly-D,L-lactic/glycolic acid (PLGA). This GBR membrane has a bi-layered structure with a dense film to prevent gingival fibroblast ingrowth and ensure mechanical function, and a micro-fibrous layer to support colonization by osteogenic cells and promote bone regeneration. Hydrolysis and biodegradation were both studied in vitro through soaking in phosphate buffered saline (PBS) and in vivo by implantation in the subcutis of rats for 4, 8, 16, 26, 48 and 52 weeks. Histology revealed an excellent colonization of the micro-fibrous layer by cells with a minimal inflammatory reaction during resorption. GBR using the synthetic PLGA membrane was evaluated on critical-size calvaria defects in rats for 4 and 8 weeks. Radiographs, micro-computed tomography and histology showed bone regeneration with the PLGA membrane, while the defects covered with a collagen membrane showed a limited amount of mineralized bone, similar to that of the defect left empty. The biofunctionality of the PLGA membranes was also compared to collagen membranes in mandible defects in rabbits, associated or not with beta-tricalcium phosphate granules. This study revealed that the bi-layered synthetic membrane made of PLGA was safer, more biocompatible, and had a greater controlled resorption rate and bone regeneration capacity than collagen membranes. This new PLGA membrane could be used in pre-implantology and peri-odontology surgery.

Treating Dehiscence During Implant Placement and Loading on Angled Abutment in Maxillary Lateral Incisor Region: A Case Report

The primary factor causing recession is the morphology and anatomy of the dentition. The facial bony plate overlying the root is usually very thin. The complete absence of bone over the facial root surface is referred to as dehiscence. Such buccal bone defects in case of implant dentistry threaten the survival of dental implant. Many surgical techniques are introduced to enhance alveolar bone volume for placing the dental implants. Guided bone regeneration (GBR) is one such established surgical technique for correcting buccal dehiscence defects, along with the use of various barrier membranes for the same. This case report describes an implant placement in the maxillary left lateral incisor region showing dehiscence on the labial cortical plate, along with bone graft and GTR membrane.

The effects of ErhBMP-2-/EGCG-coated BCP bone substitute on dehiscence around dental implants in dogs

OBJECTIVES

The purpose was to evaluate the effect of Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2)-/epigallocatechin-3-gallate (EGCG)-coated biphasic calcium phosphate (BCP) and titanium barrier membrane on dehiscence defects in dogs.

MATERIALS AND METHODS

In five mongrel dogs, the dehiscence bony defects around dental implants were surgically created and in total three implants were placed at edentulous ridge of which teeth had been extracted 12 weeks before. For the control group, BCP was applied to the dehiscence defect. For experimental groups, ErhBMP-2-coated BCP and ErhBMP-2-/EGCG-coated BCP were applied. The newly designed titanium barrier membrane was used to apply all the defects. The defects were evaluated histologically and histometrically after 12 weeks. The comparative statistics of the groups were obtained through Kruskal-Wallis test.

RESULTS

In bone-to-implant contact (BIC), bone density (BD), bone regeneration height (BRH), and bone mineralization apposition rate (BMAR), differences among groups were not found. ErhBMP-2/EGCG group appeared to have higher value. In fluorescence analysis, bone remodeling around graft material was more active in the ErhBMP-2/EGCG group.

CONCLUSION

Within the limit of this study, it is reasonable to assume that BMP-2-/EGCG-coated biphasic BCP and the newly designed titanium membrane were more beneficial in dehiscence defect healing with increased bone remodeling.

Implant treatment choice after extraction of a vertically fractured tooth. A proposal for a clinical classification of bony defects based on a systematic review of literature

OBJECTIVES

The objectives of this study were to propose a classification for the bone defects resulting after extraction of a vertically fractured tooth and to review the existing literature about the treatment of such kind of defects by means of dental implants in combination with regenerative procedures.

MATERIALS AND METHODS

An electronic search was performed on biomedical databases using a combination of appropriated search terms combined through the use of Boolean operators. All articles concerning the treatment of peri-implant bone dehiscences and fenestrations through guided bone regeneration (GBR) with at least 6 months follow-up were eligible. Outcomes data extracted from the selected articles were summarized using descriptive tables. A classification of the bone defects associated with vertical root fracture (VRF) was also proposed.

RESULTS

A total of 33 articles were included in the review. Twenty-three articles (814 implants) were about bone dehiscence treatment, ten articles presented the treatment of fenestrations, and ten (429 implants) adopted vertical bone augmentation. The percentage of bone filling was variable among different procedures and defect classification. The use of resorbable membrane was associated with better outcomes than the use of non-resorbable ones.

CONCLUSIONS

Guided bone regeneration for the management of bone defects in the presence of a VRF of the extracted tooth is a viable treatment option. The assessment of bone defect geometry prior to a tooth extraction could be clinically relevant for evaluating the feasibility and the success of immediate implant placement as well as the need of GBR.

Long-term results of implants immediately placed into extraction sockets grafted with β-tricalcium phosphate: a retrospective study

PURPOSE

The aim of this 10 year retrospective study was to evaluate the crestal bone loss around immediate implant placed in tricalcium phosphate (TCP) grafted extraction sockets

MATERIALS AND METHODS

Data were collected from files of 58 patients (33 females, 25 males, average age 54.78 years) undergoing immediate implant placement into fresh extraction socket with or without the use of TCP (Cerasorb, Curasan AG, Kleinostheim, Germany) grafting. After implant placement, horizontal gaps larger than 1.5 mm between the implant surface and the bony plate were grafted with TCP without the use of a membrane, while smaller gaps were not grafted. Two hundred fifty-four implants were inserted: 79 were placed immediately with the use of β-TCP as grafting material (group A), 175 were placed in healed extraction sites, with 61 implants placed with the use of β-TCP graft material (group B), and 114 implants were placed without any grafting material (group C). Bone loss recordings were performed using periapical radiography. Measurements were performed from the neck of the implant to level of the surrounding bone in the vertical dimension.

RESULTS

No implant was lost during the follow-up period. Statistical analysis showed no correlation between implant placement timing (delayed or immediate), the use of bone graft, and extent of bone loss.

CONCLUSION

The use of TCP (Cerasorb) as a grafting material during immediate implant placement allowed no bone loss in 72.1% of the implants, which was very similar to the nongrafted cases for which implants were placed in favorable conditions.

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.

The effect of loading in regenerated bone in dehiscence defects following a combined approach of bone grafting and GBR

OBJECTIVES

To evaluate by histology the effect of loading on the regenerated bone at dehiscence type defects around implants when treated with a combined approach of bone grafting and guided bone regeneration (GBR).

MATERIALS AND METHODS

In twelve Göttingen mini-pigs, the lower premolars and first molars were extracted and the alveolar process was reduced in width. After 3 months, two Straumann SLActive (Straumann AG, Basel, Switzerland) implants were placed in each hemi-mandible. Twelve implants were placed into the reduced alveolar ridge (group P) with no further defect or treatment on the site, while on 36 implants, buccal dehiscence defects were created and treated as follows: Group T1: synthetic bone substitute (Straumann Bone Ceramic, SBC, Straumann AG). Group T2: SBC with a polyethylene glycol membrane (Straumann MembraGel, Straumann AG); Group N: the dehiscence remained untreated. Three months following implantation, long, custom-made, healing abutments were placed in one hemi-mandible only to ensure functional loading. After 2 months, histological analysis was performed.

RESULTS

A trend for lower residual defect height and higher bone-to-implant contact was observed in the loaded sites compared with non-loaded sites in groups P, T1 and N. In group T2, the opposite effect was observed. In terms of bone formation, sites treated with SBC grafting and GBR (group T2) exhibited the largest surface area of regenerated bone followed by T1 and N. Significant resorption of the graft particles was noted in group T2 and the graft surface area occupied by SBC was significantly higher in group T1 compared with group T2 (P < 0.05).

CONCLUSIONS

Loading may have a positive effect on bone-to-implant contact in implants inserted in pristine bone or inserted in dehiscence sites and treated by grafting/no grafting.

Histologic and Histomorphometric Evaluation of Alveolar Ridge Augmentation Using Bone Grafts and Titanium Micromesh in Humans

BACKGROUND

Recently, the use of titanium micromesh for alveolar bone augmentation has drawn interest; however, only limited histologic data are available on the quality of the bone regenerated. Therefore, this study compared the use of 100% intraoral autogenous bone to a combination of intraoral autogenous bone (70%) and bovine porous bone mineral (BPBM) (30%) for alveolar ridge augmentation with titanium micromesh histologically and histomorphometrically.

METHODS

Twelve partially edentulous patients required alveolar bone augmentation before implant insertion because of ridge resorption. The defect sites, six in the maxilla and six in the mandible, were reconstructed with particulate autologous bone (control group, N = 6) or a mixture of autologous bone and BPBM (test group, N = 6) in combination with titanium micromesh. Core biopsies were taken from the defect sites 8 to 9 months after grafting at the time of implant insertion.

RESULTS

Newly formed compact bone with a well-organized lamellar pattern was identified in all specimens. In the samples taken from the test group, the BPBM particles were surrounded completely by newly formed bone with no signs of resorption. The mean total bone volume was 62.38% +/- 13.02% in the control group and 52.88% +/- 11.47% in the test group. The soft tissue volume was 37.61% +/- 13.02% and 29.96% +/- 12.58%, respectively, and the residual BPBM volume was 17.15% +/- 2.72% in the test group. No statistical difference was observed in the histologic parameters evaluated, irrespective of graft type and site (P >0.05).

CONCLUSION

Within the limits of this study, BPBM (30%) in combination with autogenous bone (70%) did not yield a lower percentage of new bone formed compared to autogenous bone alone in ridge augmentation with titanium micromesh.

Histological study on sinus lift grafting by Fisiograft and Bio-Oss

The work aims to provide a histological investigation of Fisiograft, a PLA/PGA copolymer, used as filler for bone defects in humans. The study was performed on biopsies of sinus lifts where Bio-Oss and Fisiograft gel were applied as graft material. Bone regeneration was satisfactory in all sinus lifts, even when Fisiograft was applied alone. Due to remarkable osteoclast activity, Bio-Oss granules were cleared from the majority of biopsy cores. At histology, Fisiograft gel appeared as globes enveloped by fibroblasts, displaying an epithelial-like cell appearance. Due to its solubility in solvents, undegraded Fisiograft (recorded for 7 months or more) did not stain whereas degraded Fisiograft stained positive. The loose connective tissue, that surrounded Fisiograft and bone contained isolated mastocytes. Bone grew inside the loose connective and often reached the surface of Fisiograft by intervening cells. The results seem to indicate that Fisiograft may be considered both a polymer useful for fastening bone substitutes inside a defect and in addition a material capable of prompting bone regeneration, with or without the use of a bone substitute. In addition to space-former and space-maintainer functions, Fisiograft shows potential bone stimulation function, which may be labelled as osteopromotive capability.

Multidisciplinary Treatment Approach for Enhancement of Implant Esthetics

A "team approach" that includes different specialties from the initial stages of implant treatment is important to achieve predictable and esthetically pleasing outcomes in compromised dental replacement cases. This report describes a severely compromised case that was properly managed by the combined efforts of a team of specialists. Briefly, prior to tooth extraction, orthodontic forced eruption was applied to coronally displace the attachment apparatus (i.e., hard and soft tissues). Then, atraumatic tooth extraction together with immediate implant placement was performed. The "sandwich bone augmentation" technique was used to augment the deficient buccal alveolar ridge. A second stage surgery was performed 6 months after healing, revealing 100% of bone fill/augmentation. This technique allowed fabrication of a final restoration that respected the proportions of the natural dentition in a case that would otherwise result in a poor esthetic outcome.

A comparative study of barrier membranes as graft protectors in the treatment of localized bone defects. An experimental study in a canine model

Guided bone regeneration is a predictable and well-documented surgical approach for the treatment of deficient alveolar ridges prior to endosseous implant placement. The purpose of this study was to compare a new resorbable membrane (GORE RESOLUT ADAPT Regenerative Membrane, i.e. 67% glycolide (PGA) : 33% trimethyline carbonate (TMC)) with Bio-Gide, a resorbable collagen membrane. Five canines were used in the study. Three saddle-type osseous defects were created bilaterally in edentulous areas of the mandible. The defects were filled with assayed, canine demineralized freeze-dried bone (DFDB) in a thermoplastic gelatin matrix. Using a randomized block design, four sites were covered with PGA : TMC membranes of four different porosities, one site was covered with a collagen membrane and one site consisted of DFDB alone (control). At 3 months, the animals were euthanized and the mandibles were removed en bloc for laboratory processing. A total of 30 sites were reviewed microradiographically and underwent histomorphometric analysis for bone regeneration, soft tissue presence and remaining graft material. All sites exhibited uneventful healing. A significantly higher percentage of bone regeneration was seen in the sites protected by the PGA : TMC membrane. A higher component of soft tissue was visible beneath the collagen membrane as compared with the PGA : TMC membrane. The control sites exhibited noticeable deformation of the regenerated bone secondary to collapse of the overlying periosteum. The authors conclude that the PGA : TMC membrane protected the DFDB-filled defect and allowed a greater amount of bone regeneration than the defect protected by the collagen membrane or the control.

Healing of alveolar bone in resorbable and non-resorbable membrane-protected defects. A histologic pilot study in dogs

Two main types of membrane barriers are used for bone regeneration, non-resorbable and resorbable. Polytetrafluorethilene non-resorbable membranes have been extensively studied but they require a second surgical step for removal. Although polylactic acid (PLA) resorbable membranes avoid this problem, they have not been sufficiently evaluated on bone defects. The purpose of this pilot study was to compare the healing events of bone regeneration after placement of non-resorbable or resorbable membranes and to evaluate the amount of newly formed bone 2 and 4 months after membrane placement. Mandibular second, third and fourth premolars of four adult mongrel dogs were extracted bilaterally. Two rectangular bone defects (8 mm corono-apical and 12 mm mesial-distal) were created bilaterally 3 months after tooth extractions. Each dog received two resorbable membranes and one non-resorbable membrane; one defect was left untreated. Two dogs were killed at 2 months and the remaining two at 4 months following surgery. Undecalcified sections were obtained and stained with toluidine blue and pyronin G. Histomorphometric analysis was performed using the NIH Image software. Newly formed bone was observed under both resorbable and non-resorbable membranes. The amount of regenerated bone was similar between both treatments at 2 and 4 months after surgery. At 2 months, the newly formed bone was still immature whereas at 4 months some areas of woven bone were observed. The bone formation observed in the untreated defects was significantly lower than that observed in both resorbable and non-resorbable membrane-protected defects. In summary, the present study suggests that PLA membranes can yield good results when used on bone defects while avoid a second surgical procedure.