International Journal of Periodontics & Restorative Dentistry, 02/2010

This study evaluated the clinical and histologic results of a calcium phosphate bone cement in the treatment of human periodontal intraosseous defects. Four patients with chronic advanced periodontitis in whom treatment with complete dentures was planned were recruited. The cement was implanted in one defect per subject with a presurgical probing depth of at least 7 mm and a radiographic bone defect of 4 mm or more. Patients were seen every 2 weeks for periodontal maintenance. At 6 months, clinical measurements were repeated and the tooth was removed en bloc for histologic processing. Results demonstrated that all defects resulted in probing depth reduction and, at three of the four defects, in clinical attachment level gain. However, no site showed periodontal regeneration. There was no new bone formation. New cementum and connective tissue were limited to 0.2 mm or less. Large deposits of the bone cement were noted encapsulated in connective tissue.

This retrospective radiographic study was organized to evaluate the clinical efficacy of implants with Laser-Lok microtexturing (8- and 12-µm grooves). A physical attachment of connective tissue fibers to the Laser-Lok microtexturing on the implant collar has been previously demonstrated using human histology, polarized light microscopy, and scanning electron microscopy. This analysis of 49 implants demonstrated a mean crestal bone loss of 0.44 mm at 2 years postrestoration and 0.46 mm at 3 years. All bone loss was contained within the height of the collar, and no bone loss was evident to the level of the implant threads. The radiographic evaluation of the clinical application of this implant supports previous findings that establishing a biologic seal of connective tissue fibers around a dental implant may be clinically relevant.

The objective of the following case reports was to assess whether mineralized bone replacement grafts (eg, xenografts and allografts) could be added to recombinant human bone morphogenetic protein-2/acellular collagen sponge (rhBMP-2/ACS) in an effective manner that would: (1) reduce the graft shrinkage observed when using rhBMP-2/ACS alone, (2) reduce the volume and dose of rhBMP-2 required, and (3) preserve the osteoinductivity that rhBMP- 2/ACS has shown when used alone. The primary outcome measures were histomorphometric analysis of vital bone production and analysis of serial computed tomographic scans to determine changes in bone graft density and stability. Over the 6-month course of this investigation, bone graft densities tended to increase (moreso with the xenograft than the allograft). The increased density in allograft cases was likely the result of both compression of the mineralized bone replacement graft and vital bone formation, seen histologically. Loss of volume was greater with the four-sponge dose than the two-sponge dose because of compression and resorption of the sponges. Vital bone formation in the allograft cases ranged from 36% to 53% but, because of the small sample size, it was not possible to determine any significant difference between the 5.6 mL (four-sponge) dose and the 2.8 mL (two-sponge) dose. Histology revealed robust new woven bone formation with only minimal traces of residual allograft, which appeared to have undergone accelerated remodeling or rhBMP-2-mediated resorption.

This study was conducted to compare the efficacy and feasibility of an extracellular matrix membrane (DynaMatrix) with that of an autogenous gingival graft in increasing the width of attached keratinized tissue. Six patients with an inadequate amount of attached keratinized gingiva on the bilateral facial aspect of the mandibular posterior teeth were recruited for this study. The defect sites were randomly subjected to receive either test (DynaMatrix membrane) or control (autogenous gingival graft) treatment. Both test and control sites achieved a clinically significant increase in the amount of keratinized gingiva, and the DynaMatrix membrane-treated sites blended well with the surrounding tissue, with a better appearance when compared to the autogenous gingival grafted sites. The biopsy specimens of both test and control sites appeared to be similar histologically, with mature connective tissue covered by keratinized epithelium. The results of both clinical and histologic evaluations have suggested a potential application of an extracellular matrix membrane in achieving gingival augmentation.

The use of a narrower-diameter abutment over a larger-diameter implant platform has been shown to decrease peri-implant bone resorption. This technique, known as platform switching, shifts the implant-abutment microgap inward. The aim of this study was to examine whether shifting the microgap further inward by increasing the discrepancy between the implant platform and abutment diameter would result in a decrease in crestal bone loss. Ten patients requiring mandibular or maxillary implant restorations were included in this study. The inclusion criteria called for an alveolar crest thickness of at least 8.0 mm at the implant placement site. Fifteen Certain PREVAIL implants with a body diameter of 5.0 mm, an expanded platform feature with a maximum diameter of 5.8 mm at the collar, and a prosthetic seating surface of 5.0 mm were used in lengths of 8.5, 10.0, 11.5, or 13.0 mm. The implants were connected to 4.1-mm healing abutments in a single-stage protocol. Periapical radiographs taken before and immediately after surgery, 8 weeks after implant placement, immediately after definitive prosthesis insertion, and at 12 and 18 months after loading revealed an average peri-implant bone loss of 0.30 mm. Increasing the discrepancy between the diameter of the implant platform and the restorative abutment may lead to a decrease in the amount of subsequent coronal bone loss.

This prospective, randomized, controlled clinical trial compared the clinical outcomes for a polylactic acid barrier versus a collagen membrane in conjunction with guided tissue regeneration (GTR). Thirty patients with chronic periodontitis and at least one intrabony defect of a minimum 4 mm were enrolled. Following full-mouth scaling, GTR using a collagen membrane or a polylactic acid barrier was performed at one site in each patient. At 1 week before and 6 months after surgery, probing pocket depth (PPD), clinical attachment level (CAL), marginal tissue recession, and bone fill were assessed. A significant reduction in PPD (2.50 ± 1.35 mm for the polylactic acid barrier and 2.60 ± 1.08 mm for the collagen membrane) was obtained, in addition to gains in CAL (2.40 ± 1.17 mm for the polylactic acid barrier and 2.60 ± 1.26 mm for the collagen membrane) and bone fill (0.33 ± 1.89 mm for polylactic acid barrier and 2.57 ± 1.64 mm for collagen membrane), for each group compared to baseline. Significantly, the results from 6 months after surgery showed that there was greater bone fill when the collagen membrane was used compared to the polylactic acid barrier.

Implants are placed in the wrong position for various reasons. However, severely misplaced implants cannot be restored. To correct the misplacement of implants, surgical repositioning or removal of the implants is necessary. In this study, a clinical case requiring surgical repositioning of an unrestorable implant using a trephine bur is presented. This technique focuses on minimizing damage to the osseointegration and surrounding tissues of the implant.

The esthetic outcome of implant-supported restorations has become increasingly important, especially for single-tooth implants in the esthetic zone. Because of the morphologic alterations that occur following tooth extraction, augmentation procedures are often necessary before, during, or after implantation to achieve an esthetically pleasing result. This article describes a modified technique for augmenting the soft tissue during stage-two implant surgery. The technique uses a modified roll flap, in combination with a tunneling approach to the adjacent teeth and a coronally positioned palatal sliding flap, to achieve sufficient horizontal dimensions and a scarless and harmonious architecture of the peri-implant soft tissue.

Hard and soft tissue alveolar ridge deformities occur following the extraction of teeth, creating functional and esthetic tooth replacement challenges, especially in the maxillary anterior smile zone. A surgical technique using a rotated palatal flap for ridge preservation is discussed that, whether combined with conventional fixed dentures or implant treatment for tooth replacement, provides the possibility for greatly improved esthetics. This technique, used in combination with or in preparation for implant treatment, allows for preservation of the alveolar bone height and width for improved implant size and placement options. In addition, preservation and enhancement of the soft tissue at the extraction site provides for soft tissue contours adjacent to the definitive restoration that vary little from those of the original natural tooth. Combined with conventional fixed dentures, use of this technique creates a template of the labial and interproximal sulcus of the extracted tooth, allowing for the molding of an ovate pontic replacement tooth. This results in vastly improved restorative emergence profiles with minimal or no change in the height of the labial gingival margin and the form and height of the interproximal papillae with adjacent teeth.

Bleaching systems and thickening agents lead to changes in the tooth enamel matrix as a result of an unspecific oxidation of the bleaching gel in the enamel. This reaction may result in a loss of mineral content and a decrease in microhardness. The aim of this study was to evaluate the effects of different bleaching systems and their thickening agents on the microhardness of human enamel in situ. Two dental slabs (3 x 3 x 2 mm) obtained from third molars were fixed on the buccal facial aspects of the maxillary first molars in a group of 45 volunteers. The volunteers were treated with 10% carbamide peroxide gel with carbopol as the thickening agent (group 1), 2% carbopol gel (group 2), 10% carbamide peroxide paste with poloxamer as the thickening agent (group 3), poloxamer (group 4), or 6.5% hydrogen peroxide strips for 21 days (group 5) (experimental treatment factor). The effects of the experimental treatment were evaluated by microhardness tests performed both before and after treatment (time factor). Data were submitted to split-plot analysis of variance and Tukey tests. Only time showed a statistically significant difference (P < .0001). All treatments reduced the enamel microhardness during treatment. Clinically, a reduction in microhardness can be expected after dental bleaching.