International Journal of Periodontics & Restorative Dentistry, 01/2006

Histologic and radiographic observations suggest that a biologic dimension of hard and soft tissues exists around dental implants and extends apically from the implant-abutment interface. Radiographic evidence of the development of the biologic dimension can be demonstrated by the vertical repositioning of crestal bone and the subsequent soft tissue attachment to the implant that occurs when an implant is uncovered and exposed to the oral environment and matchingdiameter restorative components are attached. Historically, two-piece dental implant systems have been restored with prosthetic components that locate the interface between the implant and the attached component element at the outer edge of the implant platform. In 1991, Implant Innovations introduced wide-diameter implants with matching wide-diameter platforms. When introduced, however, matching-diameter prosthetic components were not available, and many of the early 5.0- and 6.0-mm-wide implants received "standard"-diameter (4.1-mm) healing abutments and were restored with "standard"-diameter (4.1-mm) prosthetic components. Long-term radiographic follow-up of these "platform-switched" restored wide-diameter dental implants has demonstrated a smaller than expected vertical change in the crestal bone height around these implants than is typically observed around implants restored conventionally with prosthetic components of matching diameters. This radiographic observation suggests that the resulting postrestorative biologic process resulting in the loss of crestal bone height is altered when the outer edge of the implant-abutment interface is horizontally repositioned inwardly and away from the outer edge of the implant platform. This article introduces the concept of platform switching and provides a foundation for future development of the biologic understanding of the observed radiographic findings and clinical rationale for this technique.

The objective of this investigation was to determine the fate of thin buccal bone encasing the prominent roots of maxillary anterior teeth following extraction. Resorption of the buccal plate compromises the morphology of the localized edentulous ridge and makes it challenging to place an implant in the optimal position for prosthetic restoration. In addition, the use of Bio-Oss as a bone filler to maintain the form of the edentulous ridge was evaluated. Nine patients were selected for the extraction of 36 maxillary anterior teeth. Nineteen extraction sockets received Bio-Oss, and seventeen sockets received no osteogenic material. All sites were completely covered with soft tissue at the conclusion of surgery. Computerized tomographic scans were made immediately following extraction and then at 30 to 90 days after healing so as to assess the fate of the buccal plates and resultant form of the edentulous sites. The results were assessed by an independent radiologist, with a crest width of 6 mm regarded as sufficient to place an implant. Those sockets treated with Bio-Oss demonstrated a loss of less than 20% of the buccal plate in 15 of 19 test sites (79%). In contrast, 12 of 17 control sockets (71%) demonstrated a loss of more than 20% of the buccal plate. In conclusion, the Bio-Oss test sites outperformed the control sites by a significant margin. No investigator was able to predict which site would be successful without the grafting material even though all were experienced clinicians. This leads to the conclusion that a patient has a significant benefit from receiving grafting materials at the time of extraction.

The restoration of anterior teeth is a difficult task, even for an experienced operator. Currently there are many different ceramic systems that can be used to achieve highly esthetic results. These include metal-ceramics with porcelain margins, Dicor, In-Ceram, Cerestore, Hi-Ceram, IPS-Empress, Cerapearl, Optec, and CAD/CAM ceramics. While metal-ceramics have been used for more than four decades, the quest for a material that transmits and refracts light like a natural tooth has inspired research into all-ceramic restorations. The purpose of this paper is to briefly discuss the properties of each of the above-mentioned materials and clinically evaluate the optical behavior of: (1) metal-ceramic crowns with castings 2 mm short of the shoulder preparation and 360-degree porcelain margins; (2) In- Ceram Spinell restorations; and (3) IPS Empress restorations, and to compare these with metal-ceramic crowns with copings to the shoulder preparation and 180-degree porcelain margins. Light transmission characteristics and color matching were subjectively evaluated by five experienced prosthodontists who did not participate in this clinical study.

The present paper reports on three patients who underwent localized alveolar ridge augmentation using block autografts harvested from the mandibular tori. Autogenous particulate bone graft was placed at the periphery of the block. Resorbable collagen membrane was placed above the graft material. Implant placement surgery followed at 6 to 16 months after bone grafting. During implant surgery, a biopsy was taken from the block autograft. Clinical evaluation revealed incorporation of the graft material at the recipient site. No donor site complication was noted. Histologic evaluation suggested that the block autograft was vital and in an active remodeling phase at the time of implant placement. Impressions were made intraorally before and 6 months after bone grafting. Laboratory measurements revealed 13% resorption at 6 months after bone grafting while 0.53 mL of ridge augmentation was achieved 6 months after bone grafting. Linear tomographs indicated 4.33 mm of lateral alveolar ridge augmentation. This report suggests that block autografts harvested from the mandibular tori may have the potential to maintain their vitality after bone grafting, while they may demonstrate resorption rates similar to those of autografts harvested from other intraoral donor sites.

We report a case of dentoalveolar rehabilitation employing the technique of alveolar distraction osteogenesis in a 25-year-old male patient with a right posterior mandibular defect that was a result of previous tooth extractions and consequent severe loss of alveolar bone. A new method for vector control during alveolar distraction osteogenesis was used. This method consisted of placing an orthodontic wire on an immediately loaded implant (in the right third molar position) and securing it by means of resin composite to the implant and the adjacent tooth. Implant positioning and soft tissue management were performed successfully. The described treatment strategy appears to have good potential for providing an ideal final position of the regenerated bone in cases where major tissue defects exist in the posterior mandible.

Human mineralized bone allograft is a solvent-preserved allograft and is therefore composed of a unique bone substitute that differs from other forms of bone allograft processed via standard cryopreservation. During solvent preservation, the mineral and collagen structures appear to remain intact, thus possibly facilitating bony ingrowth when the mineral is used as a bone graft. This case series illustrates the histologic and clinical effects of this bone graft material for sinus elevation procedures. Histology from bone biopsy core samples of four patients revealed newly formed bone with a well-organized lamellar bone structure in general, and in some cases, remaining particles were observed in contact with surrounding newly formed bone. Histomorphometric analysis demonstrated a mean of 73.3% of bone formation (range, 66.1% to 85.0%) in the grafted sites, resulting in bone density that was similar to that of the original host bone (mean, 73.2%; range, 64.4% to 84.8%). Clinically, no complications were observed, and all implants were considered clinically osseointegrated after 6 months (range, 4 to 8 months). The results of this study suggest that human mineralized bone allograft could be successfully used in sinus lifting procedures and encourage further research of this solvent-preserved bone allograft material in oral reconstruction for future implant placement.

This report examines the clinical parameters and radiographic characteristics of two patients with Class III gingival recession who were treated with combined connective tissue grafting and root coverage with enamel matrix derivative. Both patients presented with multiple Class III recessions in the mandibular central incisors. Root coverage was achieved by connective tissue grafting in conjunction with the application of enamel matrix derivative. Soft tissue coverage of the root surfaces was achieved clinically, and radiographs showed improvement in the interproximal vertical bone defects.

The main goal of sinus augmentation is the formation of vital bone to allow tissue integration of endosseous implants to support prosthetic rehabilitation. The aim of the present investigation was to evaluate the radiographic and histologic results when granular medical-grade calcium sulfate hemihydrate was used as a grafting material in sinuses. Forty implants plus grafting material were placed in 10 patients, representing 15 sinuses, using a one-stage technique. Radiographs were taken prior to sinus augmentation, monthly until 6 months postoperatively, 9 and 12 months after implant placement, and annually thereafter. Bone biopsies were harvested from all patients for histologic and histomorphometric evaluation.

The aim of this randomized clinical trial was to carry out a biometric comparison between the orthodontic extrusion (OE, group B) technique and OE combined with fiberotomy and root planing (OEFRP, group A). Twenty single-root teeth were extruded and assigned to two different groups. In both groups, fixed orthodontic appliances were activated weekly during the course of 3 weeks. After activation, the extruded teeth were maintained in retention for a period of 8 weeks. In group A, along with weekly activation, fiberotomy and root planing were carried out on the top of the alveolar bone crest. Statistical analysis revealed that the amount of dental structure exposed was greater in group A, where the gingival margin and bone tissue remained stable (P .05). Group B presented coronal migration of the gingival tissue and bone tissue of 2 mm and 1.5 mm, respectively.