Fabio Vignoletti

Surgical protocols for ridge preservation after tooth extraction. A systematic review

OBJECTIVE This systematic review aims to evaluate the scientific evidence on the efficacy in the surgical protocols designed for preserving the alveolar ridge after tooth extraction and to evaluate how these techniques affect the placement of dental implants and the final implant supported restoration. MATERIAL AND METHODS A thorough search in MEDLINE-PubMed, Embase and the Cochrane Central Register of controlled trials (CENTRAL) was conducted up to February 2011. Randomized clinical trials and prospective cohort studies with a follow-up of at least 3 months reporting changes on both the hard and soft tissues (height and/or width) of the alveolar process (mm or %) after tooth extraction were considered for inclusion. RESULTS The screening of titles and abstracts resulted in 14 publications meeting the eligibility criteria. Data from nine of these 14 studies could be grouped in the meta-analyses. Results from the meta-analyses showed a statistically significant greater ridge reduction in bone height for control groups as compared to test groups (weighted mean differences, WMD = -1.47 mm; 95% CI [-1.982, -0.953]; P < 0.001; heterogeneity: I(2) = 13.1%; χ(2) P-value = 0.314) and a significant greater reduction in bone width for control groups compared to the test groups (WMD = -1.830 mm; 95% CI [-2.947, -0.732]; P = 0.001; heterogeneity: I(2) = 0%; χ(2) P-value = 0.837). Subgroup analysis was based on the surgical protocol used for the socket preservation (flapless/flapped, barrier membrane/no membrane, primary intention healing/no primary healing) and on the measurement method utilized to evaluate morphological changes. Meta-regression analyses demonstrated a statistically significant difference favoring the flapped subgroup in terms of bone width (meta-regression; slope = 2.26; 95% IC [1.01; 3.51]; P = 0.003). CONCLUSIONS The potential benefit of socket preservation therapies was demonstrated resulting in significantly less vertical and horizontal contraction of the alveolar bone crest. The scientific evidence does not provide clear guidelines in regards to the type of biomaterial, or surgical procedure, although a significant positive effect of the flapped surgery was observed. There are no data available to draw conclusions on the consequences of such benefits on the long-term outcomes of implant therapy.

Treatment of gingival recession defects with a coronally advanced flap and a xenogeneic collagen matrix: a multicenter randomized clinical trial

AIM To evaluate the clinical outcomes of the use of a xenogeneic collagen matrix (CM) in combination with the coronally advanced flap (CAF) in the treatment of localized recession defects. MATERIAL & METHODS In a multicentre single-blinded, randomized, controlled, split-mouth trial, 90 recessions (Miller I, II) in 45 patients received either CAF + CM or CAF alone. RESULTS At 6 months, root coverage (primary outcome) was 75.29% for test and 72.66% for control defects (p = 0.169), with 36% of test and 31% of control defects exhibiting complete coverage. The increase in mean width of keratinized tissue (KT) was higher in test (from 1.97 to 2.90 mm) than in control defects (from 2.00 to 2.57 mm) (p = 0.036). Likewise, test sites had more gain in gingival thickness (GT) (0.59 mm) than control sites (0.34 mm) (p = 0.003). Larger (≥3 mm) recessions (n = 35 patients) treated with CM showed higher root coverage (72.03% versus 66.16%, p = 0.043), as well as more gain in KT and GT. CONCLUSIONS CAF + CM was not superior with regard to root coverage, but enhanced gingival thickness and width of keratinized tissue when compared with CAF alone. For the coverage of larger defects, CAF + CM was more effective.

Early healing of implants placed into fresh extraction sockets: an experimental study in the beagle dog. De novo bone formation

OBJECTIVES Describe the early phases of tissue integration in implants placed into fresh extraction sockets and test whether a new implant surface nano-topography (DCD nano-particles, Nanotite) promotes early osseointegration when compared with minimally rough surface implants (DAE, Osseotite). MATERIAL AND METHODS Sixteen beagle dogs received 64 test and control implants randomly installed into the distal socket of (3)P(3) and (4)P(4). Histomorphometric analysis of bone to implant contact (BIC) and bone area was performed at 4 h, 1, 2, 4 and 8 weeks. RESULTS Wound healing initiated with a coagulum that was substituted by a provisional matrix at 1 week. Bone formation started concomitant to a marked bone resorption. At 2 weeks, woven bone formation was evident and gradually remodelled into lamellar bone at 4 and 8 weeks. BIC increased similarly throughout the study in both groups with a tendency to higher percentages for the test devices at 2 and 4 weeks. The influence of the DCD nano-particles was more evident at the fourth premolar site. CONCLUSION Osseointegration occurred similarly at both implant groups, although the socket dimension appeared to influence bone healing. It is suggested that the enhanced nano-topography has a limited effect in the immediate implant surgical protocol.

Immediate implants at fresh extraction sockets: bone healing in four different implant systems.

OBJECTIVES To describe the differences in bone healing, when placing four different implant systems in fresh extraction sockets. MATERIAL AND METHODS Eight beagle dogs received implants randomly installed into the distal socket of three P3 and four P4. Four-implant systems were evaluated. Each animal provided four test implant sites. All animals were sacrificed at 6 weeks after implant placement, providing specimens for histo-morphometric analysis of bone to implant contact (BIC), bone area, new bone formation, as well as histometric measurements of the ridge alterations. RESULTS No statistically significant difference was observed among the four-implant systems. The mean BIC % ranged between 58.5% and 72.1%. Bone modelling of the buccal plate was marked and amounted approximately to 2.5 mm, independently of the system used. CONCLUSION This study failed to demonstrate differences in the healing pattern after 6 weeks when placing four different implant systems in fresh extraction sockets. In spite of achieving predictable osteointegration with the four implants studied, the occurrence of buccal bone resorption may limit the use of this surgical approach.

Quality of reporting of experimental research in implant dentistry. Critical aspects in design, outcome assessment and model validation

OBJECTIVE The aim was to assess the quality of reporting of experimental research in implant dentistry by a critical evaluation of study design, outcome assessments and model validation. MATERIAL & METHODS An online search was performed using the MEDLINE. Experimental studies performed in both animals and humans were included. A’stratified random sample of the included studies was extracted and used for quantitative and qualitative analyses. Modified versions of the ARRIVE guidelines were used for quality assessment. RESULTS A total of 982 papers were eligible and used for quantitative analyses. A’stratified random sample of 193 publications was extracted. The dog model was the most used experimental model whereas experimental studies on humans were few. Intra-oral experimental sites dominated in human, monkey, dog and mini-pig studies. Extra oral sites dominated in rabbit, rodent and goat/sheep studies. Studies on the pathogenesis and treatment of peri-implant diseases were few. CONCLUSION Different animal models, experimental protocols and methods of analysis have been used to address different areas of experimental research in implant dentistry. Standardized designs for investigations within this type of experimental research seem to be lacking. Furthermore, in many of these studies there were limitations in reporting on methodology and statistical methods.

Early healing of implants placed into fresh extraction sockets: an experimental study in the beagle dog. III: soft tissue findings

AIM To describe histologically the early phases of soft tissue healing to implants placed into fresh extraction sockets. MATERIALS AND METHODS In 16 beagle dogs, 64 3.25-mm-wide cylindrical screw implants were inserted into the distal sockets of the third and fourth lower premolars using a one-stage trans-mucosal healing protocol. Biopsies were then taken at 1, 2, 4 and 8 weeks and prepared for histological examination. RESULTS One-week specimens showed a junctional epithelium and an underlying loose connective tissue rich in inflammatory cells. At 2 weeks, signs of epithelial proliferation and a more organized connective tissue were observed. At 4 and 8 weeks, inflammation was absent; the epithelium appeared mature and in close contact with the surface of the healing abutment or the implant. The connective tissue was dense in an area close to the implant surface and the fibres were aligned parallel to the implant surface. The soft tissue dimensions at 8 weeks were approximately 5 mm, including about 3-3.5 mm of epithelium and 1-1.5 mm of connective tissue. CONCLUSION Soft tissue healing to implants placed in fresh extraction sockets may result in a longer epithelial interface than implants placed in a healed ridge.

Periodontal regeneration following implantation of cementum and periodontal ligament-derived cells.

BACKGROUND AND OBJECTIVE The periodontal regeneration of bone defects is often unsatisfactory and could be largely improved by cell therapy. Therefore, the purpose of this study was to evaluate the regenerative potential of implanting canine cementum-derived cells (CDCs) and canine periodontal ligament-derived cells (PDLDCs) in experimentally created periodontal intrabony defects in beagle dogs. MATERIAL AND METHODS Cells were obtained from premolars extracted from four beagle dogs. Three-wall intrabony periodontal defects, 3 mm wide and 4 mm deep, were surgically created in their second and fourth premolars and plaque was allowed to accumulate. Once the defects were surgically debrided, periodontal regeneration was attempted by random implantation of collagen sponges embedded with 750,000 CDCs, 750,000 PDLDCs or culture medium. After 3 mo of healing, specimens were obtained and periodontal regenerative outcomes were assessed histologically and histometrically. RESULTS The histological analysis showed that a minimal amount of new cementum was formed in the control group (1.56 ± 0.39 mm), whereas in both test groups, significantly higher amounts of new cementum were formed (3.98 ± 0.59 mm in the CDC group and 4.07 ± 0.97 mm in the PDLDC group). The test groups also demonstrated a larger dimension of new connective tissue, resulting in a significantly more coronal level of histological attachment. CONCLUSION This proof-of-principle study suggests that cellular therapy, in combination with a collagen sponge, promoted periodontal regeneration in experimental intrabony periodontal defects.

Clinical and histological healing of a new collagen matrix in combination with the coronally advanced flap for the treatment of Miller class‐I recession defects: an experimental study in the minipig

AIM To describe the histological and clinical outcomes of the use of a xenogeneic collagen matrix (CM) in combination with the coronally advanced flap (CAF) in the treatment of localized Miller class-I gingival recessions. MATERIAL AND METHODS Gingival recession defects were surgically created on 12 minipigs. The defects were randomly treated with either the CAF procedure and the interposition of a CM (test) or the CAF alone (control). Clinical and histological outcomes at 1, 4 and 12 weeks were evaluated. RESULTS Histometrically, in the test group, there was a shorter junctional epithelial dimension [2.26 (SD 0.23) mm] compared with the control [2.79 (SD 0.77) mm]. On the contrary, the amount of newly formed cementum was larger in the test group [1.08 (SD 0.41) mm] than in the control group [0.75 (SD 0.25) mm], although the differences were not statistically significant. CONCLUSIONS Both techniques rendered similar clinical outcomes, achieving complete root coverage at the end of the study. Nevertheless, the CM graft attained more tissue regeneration, characterized by a shorter epithelium and a larger new cementum formation. The use of a xenogeneic CM resulted in the incorporation of the xenograft within the adjacent host connective tissues in the absence of significant inflammation.

Clinical and histological evaluation of an acellular dermal matrix allograft in combination with the coronally advanced flap in the treatment of miller class I recession defects: an experimental study in the mini-pig

OBJECTIVES To study the wound healing of acellular dermal matrix (ADM) allografts when used together with coronally advanced flaps (CAF) in the treatment of localized gingival recessions in the mini-pig experimental model. MATERIAL AND METHODS Dehiscence defects 4 x 5 mm were surgically created in one buccal root surface in each quadrant of PI, II, or III in three mini-pigs. They were then treated with CAF and the interposition of either a connective tissue graft (CTG) or ADM. As the primary outcome, the histological interface between the ADM and the root surface was studied and was compared with CTG. As secondary outcomes, we assessed the amount and quality of the keratinized tissue and clinical outcomes in terms of root coverage and recession reduction. RESULTS At 3 months, the CTG group attained a mean 76% root coverage, versus 62% in the ADM group. The histological interface with the root surface was similar in both groups. The apical migration of the epithelium was 1.79+/-0.46 mm for the CTG and 1.21+/-0.35 mm for ADM. Newly formed cementum was observed with both treatments. New bone and a newly formed periodontal ligament were shown in five specimens in the ADM group and in three in the CTG group. CONCLUSION Both materials showed similar clinical and histological outcomes.

Soft tissue wound healing at teeth, dental implants and the edentulous ridge when using barrier membranes, growth and differentiation factors and soft tissue substitutes

AIM To review the biological processes of wound healing following periodontal and periimplant plastic surgery when different technologies are used in a) the coverage of root and implant dehiscences, b) the augmentation of keratinized tissue (KT) and c) the augmentation of soft tissue volume. MATERIALS & METHODS An electronic search from The National Library of Medicine (MEDLINE-PubMed) was performed: English articles with research focus in oral soft tissue regeneration, providing histological outcomes, either from animal experimental studies or human biopsy material were included. RESULTS Barrier membranes, enamel matrix derivatives, growth factors, allogeneic and xenogeneic soft tissue substitutes have been used in soft tissue regeneration demonstrating different degrees of regeneration. In root coverage, these technologies were able to improve new attachment, although none has shown complete regeneration. In KT augmentation, tissue-engineered allogenic products and xenogeneic collagen matrixes demonstrated integration within the host connective tissue and promotion of keratinization. In soft tissue augmentation and peri-implant plastic surgery there are no histological data currently available. CONCLUSIONS Soft tissue substitutes, growth differentiation factors demonstrated promising histological results in terms of soft tissue regeneration and keratinization, whereas there is a need for further studies to prove their added value in soft tissue augmentation.