International Journal of Periodontics & Restorative Dentistry, 04/2011

This retrospective case series reports on the use of freeze-dried bone allograft (FDBA) combined with a purified recombinant protein of platelet-derived growth factor BB (PDGF-BB) for the treatment of periodontal intraosseous defects in 50 consecutive patients. The mean pretreatment measurements for clinical attachment level and probing depth were 7.9 ± 1.6 mm and 7.8 ± 1.4 mm, respectively. At 6 months, mean clinical attachment level was 3.9 ± 1.4 mm, reflecting an improvement of 4.1 ± 1.3 mm, whereas mean probing depth was reduced to 3.0 ± 1.2 mm, corresponding to a reduction of 4.8 ± 1.4 mm. These clinical results indicate that the combined use of FDBA and PDGF-BB can lead to substantial improvements in clinical parameters.

The primary aim of this study was to evaluate the differences in labial plate thickness in patients identified as having thin versus thick/average periodontal biotypes. The association between biotype and labial plate thickness was evaluated by correlating information obtained from cone beam computed tomographs, diagnostic impressions, and clinical examinations of the maxillary anterior teeth (canine to canine) in 60 patients. Compared to a thick/average biotype, a thin biotype was associated with thinner labial plate thickness (P < .001), narrower keratinized tissue width (P < .001), greater distance from the cementoenamel junction to the initial alveolar crest (P = .02), and probe visibility through the sulcus. There was no relationship between biotype and tooth height-to-width ratio or facial recession. Periodontal biotype is significantly related to labial plate thickness, alveolar crest position, keratinized tissue width, gingival architecture, and probe visibility but unrelated to facial recession.

As part of the paradigm shift toward more minimally invasive surgical procedures, increasing numbers of references to laser-mediated flapless crown lengthening are noted in the published literature. The vast majority of these references are noncontrolled case reports or technique-focused articles. Therefore, prospective, randomized controlled studies that objectively examine the safety and efficacy of flapless crown lengthening are lacking. The current case series represents an initial attempt to examine some of the clinical issues posed by this minimally invasive flapless approach. Ultimately, only welldesigned controlled clinical trials can yield the type of evidence-based data necessary to categorize this approach to crown lengthening as standard-ofcare treatment.

This prospective split-mouth pilot case series compared the use of a bilayer collagen matrix (CM) to an autogenous gingival graft (AGG) in the ability to increase the zone of keratinized attached gingiva. Five patients with inadequate amounts of keratinized attached gingiva bilaterally in the posterior mandible were enrolled using a split-mouth design. There were statistically significant increases in attached gingiva at all test (CM) and control (AGG) sites. The CM sites at 12 months blended well with surrounding tissues, while the AGG sites were morphologically dissimilar to the adjacent areas. Biopsy results showed intrapatient histologic similarity between CM and AGG treatments, with all sites exhibiting mature connective tissue covered by keratinized epithelium. Thus, the obtained data support further investigations in evaluating the role of CM as a viable alternative to AGG in augmenting areas deficient in keratinized gingiva.

Patients do not view dental implants as an object of desire but seek a way to replace teeth that will be as cost-effective and minimally traumatic as possible. Nowadays, anterior fixed partial dentures can provide an esthetic result that is difficult to distinguish from the natural dentition. Consequently, any implant-supported prosthesis will be compared to the esthetic and functional standards set by conventional tooth-supported restorations. The restoration of the four maxillary incisors by means of an implant-supported prosthesis is one of the most challenging situations in implant dentistry. The questions of how many implants should be placed and where they should be positioned are especially important for achieving a superior end result. This article proposes and describes the placement of two platform-switched implants in the central incisor positions as a means of achieving the correct biomechanical behavior of the prosthesis, along with the best possible esthetic results.

This paper reports on a patient who underwent horizontal ridge augmentation using recombinant human platelet-derived growth factor BB (rhPDGF-BB) in combination with a collagenate equine block. Ninety days after the first surgery, 8 mm of new bone was noted on a computed tomography scan, and three 5-mm implants were placed. Histology, performed using confocal laser scanning microscopy, showed a large amount of newly formed bone well characterized with osteon and resorption lacunae, which demonstrated the intense bone remodeling. This study supports the use of rhPDGF-BB in combination with allograft blocks.

Implant placement in the edentulous maxilla often represents a clinical challenge because of insufficient bone height after crestal bone resorption and maxillary sinus pneumatization. In this study, tissue engineering techniques were used to increase bone height in the posterior maxilla before implant placement. Periosteal biopsies were harvested, and osteoblast precursor cells were isolated and cultured on three-dimensional fleeces (nonwoven polyglactin-910 fibers connected by poly-p-dioxanon bonding sites) in vitro. Tissue-engineered bone chips were implanted into the sinus cavity using a lateral window approach. Four months post-sinus augmentation, implants were placed and subsequently restored. During a 12-month follow-up period, no implant failure was observed.

Rehabilitation of the atrophic alveolar ridge is often problematic. Bone augmentation surgery may be hindered by a lack of surfaces from which blood vessels can spread during the initial stages of bone regeneration. If heterologous biomaterials are used as an alternative to autologous bone grafts, the standard delivery formats-blocks or granules-both have significant limitations. The present study was designed to evaluate the effectiveness of an alternative material, a flexible equine bone sheet, for vertical ridge augmentation. Forty-nine implants were placed in 18 patients whose vertically atrophic maxillary or mandibular ridges were simultaneously augmented with flexible cortical bone sheets derived from equine femurs. After 4 months, the ridge volume for all patients was completely restored, all implants had successfully osseointegrated, and definitive prostheses were placed. These parameters remained unchanged throughout 3 years of follow-up.

Immediate implant placement into extraction sockets has been widely reported in the dental literature, but few studies have evaluated immediate loading of such implants. This retrospective study evaluated 206 implants placed into fresh extraction sites using a flapless technique, followed by immediate provisionalization with nonoccluding single-tooth restorations and definitive restoration within 2 weeks. Cumulative survival and success rates were 98.77% (mean follow-up, 23.1 months). Periodontitis did not influence the outcome adversely. Within the limitations of this study, immediate implant placement and restoration, followed by definitive loading within 2 weeks, achieved outcomes comparable to those historically reported for delayed implants.

Bone modeling and remodeling following tooth extraction has been studied extensively. The reason for bone loss during the remodeling process is multifactorial, and the primary reason for this loss is still yet to be determined. The aim of this study was to examine the type of bone and the blood supply to the buccal bone in monkeys. Six maxillary arches from six monkeys were used. The arches were divided into three sections: right posterior, anterior from canine to canine, and left posterior. Blocks were decalcified and prepared for histologic processing and examination. Modified Masson trichrome and retic staining were used. Histologic sectioning demonstrated that the blood supply to the buccal bone came from the inner (socket) side of the alveolus, the periodontal ligament, the adjacent interdental bone, and the supraperiosteal vessels emanating from the covering gingiva or mucosa. Histologic examination showed that the buccal bone was composed of bundle and cortical bone. The thickness of the buccal bone was not uniform coronoapically, and the thinnest area of buccal bone was the coronal portion.

The emergence of implant dentistry has led to the need for bone augmentation procedures. With the removal of a tooth, there is an inevitable three-dimensional (3D) loss of alveolar bone. More often than not, horizontal bone loss occurs at a faster rate and to a greater extent compared to vertical bone loss. This led to the development of several horizontal bone augmentation techniques, such as guided bone regeneration, ridge expansion, distraction osteogenesis, and block grafts. These proposed augmentation techniques aim to place the implant in an ideal 3D position for successful restorative therapy. The literature has shown that horizontal bone augmentation is fairly predictable if certain criteria are fulfilled. However, with numerous techniques and materials currently available, it is difficult to choose the most suitable treatment modality. A search of the literature available was conducted to validate the decision-making process when planning for a horizontal ridge augmentation procedure. The decision tree proposed in this paper stems from the 3D buccolingual bone width available at the site of implant placement (>= 3.5 mm, < 3.5 mm, or 4 to 5 mm). In each dimension, techniques are advised after considering factors such as the tissue thickness, the arch position, and the availability of autogenous bone. The decision tree provides insight on how clinicians can choose the most appropriate and predictable horizontal ridge augmentation procedure to minimize unnecessary complications.

Gingival recessions may be classified according to a number of different systems. One of the most frequently used systems both in the literature and everyday practice is that proposed by Preston D. Miller in 1985. This classification assigned recessions to four different classes and gave a prognosis with regard to complete root coverage for each of the four situations following surgical treatment. According to Miller himself, complete coverage may be predicted in both Class I and II recessions, whereas its attainment is unpredictable in Class III and impossible in Class IV. Given that complete root coverage is attained in some Class III recessions, an investigation was planned to determine the presurgical variables that could help predict these results. Presurgical, surgical, and postsurgical conditions were studied for 121 Class III recessions in 50 patients, of which 47% achieved complete root coverage. Following statistical analysis using linear regression techniques, it was observed that the outweighing variables that explained these results were: soft tissue interproximal integrity, the use of grafts with a thickness of greater than 2 mm, interproximal bone loss not exceeding 3 mm, and an initial recession width not greater than 3 mm. Complete root coverage is possible in some Class III recessions. The Miller classification could be extended if these findings are confirmed by further research.

The aim of this study was to evaluate the correlation between the osseointegration of dental implants and tissue-engineered bone using a nanofiber scaffold, PuraMatrix (PM). The first molar and all premolars in the mandibular regions of dogs were extracted, and three bone defects were prepared with a trephine bur on both sides of the mandible after 4 weeks. The experimental groups were as follows: (1) PM, (2) PM and dog mesenchymal stem cells (dMSCs), (3) PM, dMSCs, and platelet-rich plasma, and (4) control (defect only). Implants were placed in the prepared areas 8 weeks later and were assessed by histologic and histomorphometric analyses (bone-to-implant contact [BIC]). The BICs for groups 1, 2, 3, and 4 were 40.77%, 50.35%, 55.64%, and 30.57%, respectively. The findings indicate that PM may be useful as a scaffold for bone regeneration around dental implants.

Conventional orthopedic implants are composed from titanium. To improve some characteristics (ie, volumetric porosity, modulus of elasticity, frictional modulus), a new porous tantalum biomaterial has been developed and its biocompatibility reported. By using DNA microarrays containing 20,000 genes, several genes whose expression were significantly up- or downregulated were identified in an osteoblastlike cell line (MG63) cultured with tantalum powder (TP). The differentially expressed genes cover a broad range of functional activities: signaling transduction; transcription; cell cycle regulation, proliferation, and apoptosis; and cytoskeleton formation. To the authors' knowledge, the data reported represent the first genetic portrait of TP.

Two evaluation techniques (histology and microcomputed tomography [micro- CT]) were synergistically applied to calvarial bone graft to verify whether additional bone information can be obtained for the assessment of bone grafts. Ten extensive bone defects in the anterior and posterior maxilla or mandible involving crestal bone were treated by grafted blocks and chips of autogenous calvarial bone. The grafts were fixed with lag screws and left to heal for 4 months. No complications were observed. At surgical reentry for implant placement, a cylindric bone biopsy of both graft and native bone was retrieved and analyzed with both micro-CT and standard histology. Two- and three-dimensional (2D, 3D) micro-CT analyses allowed bone connectivity indices to be evaluated. This is useful for estimating bone strength and observing bone structure. The integration of the grafted calvarial bone with the residual bone of the recipient site was considered satisfactory. Histologic analysis allowed observations to be made at a higher resolution. Calvarial bone grafts seem to have positive effects when used as grafting materials. The application of both histologic and micro-CT techniques allows a better evaluation of grafted bone by concurrently allowing 2D and 3D visual and morphometric analysis of bone vitality, structure, turnover, and strength.