International Journal of Periodontics & Restorative Dentistry, 02/2008

This human proof-of-principle study was designed to investigate the possibility of achieving a physical connective tissue attachment to the Laser-Lok microchannel collar of a dental implant. Its 2-mm collar has been micromachined to encourage bone and connective tissue attachment while preventing apical migration of the epithelium. Implants were harvested with the surrounding implant soft and hard tissues after 6 months. The histologic investigation was conducted with light microscopy, polarized light, and scanning electron microscopy.

The objective of the present experiment was to evaluate the effect on hard tissue modeling and remodeling of the placement of a xenograft in fresh extraction sockets in dogs. Five mongrel dogs were used. Two mandibular premolars (4P4) were hemisected in each dog, and the distal roots were carefully removed. In one socket, a graft consisting of Bio-Oss Collagen (Geistlich) was placed, whereas the contralateral site was left without grafting. After 3 months of healing, the dogs were euthanized and biopsies sampled. From each experimental site, four ground sections (two from the mesial root and two from the healed socket) were prepared, stained, and examined under the microscope. The presence of Bio-Oss Collagen failed to inhibit the processes of modeling and remodeling that took place in the socket walls following tooth extraction. However, it apparently promoted de novo hard tissue formation, particularly in the cortical region of the extraction site. Thus, the dimension of the hard tissue was maintained and the profile of the ridge was better preserved. The placement of a biomaterial in an extraction socket may promote bone modeling and compensate, at least temporarily, for marginal ridge contraction.

The purpose of the present clinical study was to evaluate the biologic stability of alumina-zirconia implant abutments by histologic and radiographic examination. Nineteen partially edentulous patients were treated with 37 external-hexagon implants. After a healing period of 3 to 6 months, alumina-zirconia abutments were connected and restored with cemented single crowns or short-span fixed partial dentures. Periapical radiographs were taken at the time of prosthesis delivery and after 3, 6, and 12 months of follow-up. Crestal alveolar bone level changes were assessed by digital subtraction of consecutive images, and 1-way analysis of variance was used for statistical analysis. No implant, abutment, or restoration failed during the observation period. Bone level changes were statistically insignificant and histologic examination revealed no signs of inflammation. Stable and healthy soft and hard tissue conditions may be expected around alumina-zirconia abutments after 1 year of clinical service. However, long-term data are needed to confirm the present results.

The clinical applicability and predictability of osseointegrated implants in healthy patients have been studied extensively. Although successful treatment of patients with medical conditions including diabetes, arthritis, and cardiovascular disease has been described, insufficient information is available to determine the effects of diabetes on the process of osseointegration. An implant placed and intended to support an overdenture in a 65-year-old diabetic woman was prosthetically unfavorable and was retrieved after 2 months. It was then analyzed histologically. No symptoms of implant failure were detected, and histomorphometric evaluation showed the bone-to-implant contact percentage to be 80%. Osseointegration can be obtained when implants with a dual-acid-etched surface are placed in properly selected diabetic patients.

Treatment of intrabony periodontal defects with a combination of an enamel matrix derivative (EMD) and a natural bone mineral (NBM) has been demonstrated to significantly improve clinical parameters such as probing depth (PD) and clinical attachment level (CAL). However, long-term clinical and histologic data on treatment with this approach are limited. The aim of the present study was to present the 5-year clinical and histologic results following treatment of intrabony defects with a combination of EMD + NBM. Eleven healthy patients, all with advanced chronic periodontitis and one deep intrabony defect each, were consecutively treated with a combination of EMD + NBM. PD, recession of the gingival margin (GR), and CAL were measured just before and at 1 and 5 years after treatment. The primary outcome variable was CAL. No adverse healing responses were observed. Mean PD, GR, and CAL were significantly reduced at 1 year and at 5 years versus baseline values. Histologic analysis of a mandibular second molar, extracted 5 years after treatment with EMD + NBM, demonstrated bone formation around the NBM particles. Regenerative surgery with the combination of EMD + NBM may result in bone formation, and the obtained clinical results can be maintained over a period of 5 years.

This study compared bone grafting regimens and different implant surfaces used for sinus augmentation and presented long-term implant success rates in augmented sinuses. Two hundred fifty-seven consecutive patients with 625 implants were evaluated retrospectively. In phase 1, 188 sinuses were grafted with (1) autograft alone; (2) autograft + demineralized freeze-dried bone allograft (DFDBA) + absorbable hydroxyapatite (AHA) in a ratio of approximately 1:3:3; or (3) DFDBA + AHA + nonabsorbable HA (NHA) in a ratio of approximately 1:1:1. In phase 2, grafting regimen 3 (combination of DFDBA + AHA + NHA) was used in another 69 patients. Data were analyzed based on bone grafting regimen, implant surface texture, and time of implant placement (immediate or delayed). In phase 1, graft type 3 had the lowest implant failure rate (2.7%), followed by type 2 (14.3%) and type 1 (44.4%). The overall implant failure rate was 3.6%. Smooth implants showed the highest failure rate (21.8%), followed by titanium plasma-sprayed (2.9%) and HA-coated (0.7%) implants. In phase 2, the overall implant survival rate was 92.5% after 3 years. Smooth implants showed the highest failure rate (41.7%), followed by sand-blasted, large-grit, acid-etched (6.8%) and HA-coated (3.4%) implants. All failures occurred when implants were placed simultaneously with sinus grafts. This study suggests that long-term implant success can be obtained when maxillary sinuses are augmented with a combination of DFDBA + AHA + NHA. Rough surfaces and delayed implant placement seem to increase implant success in these areas.

This study histologically evaluated recombinant human platelet-derived growth factor-BB (rhPDGF-BB) in combination with beta-tricalcium phosphate (ß-TCP) for the treatment of human intraosseous periodontal defects. Eight patients, each with two teeth treatment planned for extraction, were enrolled. Presurgical measurements included probing depth, clinical attachment level, and recession. Initial surgery consisted of flap reflection, debridement, placement of a root notch through the base of calculus, scaling and root planing, root biomodification with 50 mg/mL tetracycline, grafting with rhPDGF-BB + ß-TCP, and complete wound closure. One tooth in each patient was treated with 0.3 mg/mL of rhPDGF-BB + ß-TCP, and the other tooth was treated with 1.0 mg/mL of rhPDGF-BB + ß-TCP. After a minimum of 6 months of healing, postsurgical clinical measurements were made, and teeth were removed en bloc. Soft tissue healing was uneventful. Histologic evaluation demonstrated new bone, cementum, and periodontal ligament coronal to the reference notch in 13 of the 16 teeth. Six of the eight 0.3- mg/mL sites and seven of the eight 1.0-mg/mL sites demonstrated periodontal regeneration. This study provides proof of principle that 0.3 mg/mL and 1.0 mg/mL of rhPDGF-BB and ß-TCP can promote periodontal regeneration in human intraosseous periodontal defects.

This clinical case report presents a new technique for reconstructing the vertical and horizontal dimensions of the alveolar ridge using a mandibular bone block at sites planned for single implants. Augmentation was eased with the use of a mandibular bone block, which was shaped after placement with a round bur to passively fit the dimensions of the defect, at the recipient site. After treatment, approximately 7 mm of horizontal and 3 mm of vertical augmentation were gained. Histologic observation showed that the grafted bone was well integrated with the original bone. The volume of tissue gained was sufficient for placing an implant in an optimal position. The gain in the vertical and horizontal dimensions allowed an esthetic result with a single-tooth crown.

The case report describes the distraction osteogenesis of a small bone fragment supporting a maxillary central incisor that had become ankylosed and infraoccluded after trauma. After initial orthodontic treatment, surgery was performed, entailing a trapezoidal osteotomy with minimal periosteal elevation through a horizontal incision. On this occasion, a device was applied, anchored to the tooth, and activated by a micrometer screw. On completion of distraction, the fragment was retained for 5 months. The ankylosed tooth was then removed, and an implant was inserted and provided with an immediate provisional prosthesis without occlusal loading. Five months later, a definitive prosthesis with occlusal loading was applied and is still in place 1 year later without any problems.