International Journal of Periodontics & Restorative Dentistry, 06/2007

A single-tooth implant in the esthetic region has good potential for success, but it is still challenging to restore multiple-tooth defects with implant-supported prostheses that resemble the natural dentition. This article suggests a strategy to provide a more predictable protocol for esthetic implant treatment for multiple-tooth defects using the root submergence technique (RST). By maintaining the natural tooth root with the RST, a much greater amount of surrounding tissue may be preserved than with the commonly used socket preservation technique, which almost always leads to crestal bone resorption and thus reduction of the height of the interdental papillae and width of the edentulous ridge. RST instead maintains the natural attachment apparatus of the tooth in the pontic site, which in turn allows for complete preservation of the alveolar bone frame and assists in the creation of an esthetic result in adjacent multiple-tooth-replacement cases. In situations with periodontal bone loss, orthodontic extrusion is required to create the underlying bone support for the papilla that is necessary to guarantee predictability.

The purpose of this study was to evaluate the periodontal variables of impacted maxillary canines that were treated with a combined surgical and orthodontic approach aimed at reproducing the physiologic eruption pattern of canines. Twenty-five patients who presented with unilateral impacted maxillary canines were consecutively enrolled (age range, 13.2 to 23.2 years). They were treated with a surgical flap and orthodontic traction directed to the center of the crest and were evaluated periodontally at the end of treatment and again at a follow-up visit (2 to 5 years posttreatment). Pocket depth, keratinized tissue width, and gingival recession were recorded. At the end of orthodontic treatment, all 25 treated canines presented with normal pocket depth (2.0 ± 0.3 mm) and a normal amount of keratinized tissue (5.0 ± 1.2 mm). No sites showed gingival recession. At the follow-up visit, both pocket depths and keratinized tissues were slightly reduced. The combined technique permits traction of the impacted canines to the center of the crest, simulating the physiologic eruption pattern and resulting in correct alignment and good periodontal status.

This study used backscattered electron microscopy (BSE-SEM) to analyze specimens in which bone was augmented both horizontally and vertically with a xenograft scaffold and recombinant human platelet-derived growth factor (rhPDGF-BB), with or without a resorbable collagen membrane. The study objective was to compare percentage weight and volume calcium-phosphorus ratios of regenerated bone and native bone and the nature of the bony contact with two different implant surfaces. Examination of the nature of the mineralized tissues by BSE-SEM provides an understanding of the composition and element ratio of bone regenerated from nonautogenous grafts. The data collected demonstrated no statistically significant difference between regenerated bone and native bone in the two tested groups. Our observations suggest that bone regenerated via nonautogenous grafts displays composition, structure, and physical properties very similar to those of native bone. Similarly, no significant differences were observed at the bone-implant interface between bone regenerated proximal to oxidized versus machined implants.

The purpose of this study was to evaluate treatment of resorbed posterior mandibles with interpositional bone grafts (the "sandwich" technique) and implant-supported prostheses. Six consecutive patients with resorbed posterior mandibles (seven sites) were treated by the sandwich osteotomy technique with an interpositional bone graft harvested from the iliac crest. Vertical bone height was measured before surgery and 3 to 4 months later, prior to implant placement, on computed tomography scans to evaluate the augmentation obtained. In all the treated sites it was possible to place implants. None of the 21 implants placed failed, and minimal bone resorption was present 14 to 16 months after the prosthetic loading. If confirmed by long-term follow-up studies and more cases, these findings suggest that interpositional bone grafting in the posterior mandible could be a viable alternative to other surgical techniques.

This work evaluates the data gathered over a period of 10 years on implants placed with the edentulous ridge expansion (ERE) technique by a group of specially trained and experienced surgeons. Between January 1992 and December 2001, 1,715 consecutive implants were placed with the ERE technique by nine different dental surgeons using a common surgical protocol. The implants were followed up using a common protocol and a specific database for the collection of clinical information on the patient, surgery, and follow-up, including the 1986 Albrektsson et al criteria for implant success. All data gathered at the end of the study period were placed in a common database. The overall success rate over the 10-year follow-up period was 95.7%.

The objective of this study was to evaluate, by scanning electron microscopy, the marginal and internal fit of all-ceramic three-unit fixed partial denture (FPD) frames fabricated by computer-assisted design/computer-aided machining (CAD/CAM) and CAM techniques using blocks of infiltration ceramic, high-strength yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) zirconia sinter ceramic, high-strength dense sintered Y-TZP zirconia ceramic, and glass ceramic. Slip-cast infiltration ceramic was used as a traditional control. The cementation interface widths of the FPD frame copings on butt (A) shoulders of Cerec In-Ceram zirconia (A1, 53 ± 17 µm) were smaller than those of slip-cast In-Ceram zirconia (A6, 113 ± 25 µm). Cerec Y-TZP zirconia (A2, 53 ± 9 µm) and DCS Y-TZP zirconia (A4, 32 ± 6 µm) interfaces were both significantly smaller than those of Cercon Y-TZP zirconia (A5, 120 ± 6 µm). Internally, A2 (103 ± 14) interfaces were smaller than A4 interfaces (144 ± 15 µm). On chamfer shoulders (B), Cerec Y-TZP zirconia (B1, 71 ± 5 µm) interfaces were smaller than Cercon interfaces (B2, 129 ± 38 µm); internally, B1 (80 ± 11 µm) interfaces were smaller than B2 interfaces (130 ± 12 µm). CAD/CAM produced better marginal and internal accuracy of fit compared to slip casting and CAM techniques.

This report presents histologic results in humans following a laser-assisted new attachment procedure (LANAP) for the treatment of periodontal pockets. Six pairs of single-rooted teeth with moderate to advanced chronic periodontitis associated with subgingival calculus deposits were treated. A bur notch was placed within the pocket at the clinically and radiographically measured apical extent of calculus. All teeth were scaled and root planed with ultrasonic and hand scalers. One of each pair of teeth received treatment of the inner pocket wall with a free-running pulsed neodymium:yttrium-aluminum-garnet (Nd:YAG) laser to remove the pocket epithelium, and the test pockets were lased a second time to seal the pocket. After 3 months, all treated teeth were removed en bloc for histologic processing. LANAP-treated teeth exhibited greater probing depth reductions and clinical probing attachment level gains than the control teeth. All LANAP-treated specimens showed new cementum and new connective tissue attachment in and occasionally coronal to the notch, whereas five of the six control teeth had a long junctional epithelium with no evidence of new attachment or regeneration. There was no evidence of any adverse histologic changes around the LANAP specimens. These cases support the concept that LANAP can be associated with cementummediated new connective tissue attachment and apparent periodontal regeneration of diseased root surfaces in humans.

The objective of the present study was to observe the effect of positioning of the mandible on the accuracy of cross-sectional images obtained by reformatting computerized tomographic (CT) scans. An additional aim was to evaluate the ability of a software program (DentalVox, Era Scientific) to reconstruct these measurements on the reformatted images, regardless of the positioning of the mandible, accurately and without distortion. The test was carried out by examining a partially edentulous dry human mandible with an acrylic radiologic template. Through the use of an acrylic glass support, the mandible was positioned at angles of 0, 10, 15, 20, and 30 degrees relative to the scanning gantry, and a series of CT scans was performed that provided five sets of axial images. Each set of original axial images was reformatted by the DentalVox software, used first in its basic function, which is typical of all software for axial CT measurement (control group), and again in its function of site-specific multiplanar reconstruction (test group). The results showed that the position of the mandible in relation to the CT gantry can influence the precision of the linear measurements. The error ranged from 2% to 51%. The DentalVox software allowed the reconstruction of cross-sectional images with very little distortion regardless of the mandibular position.

Demineralized freeze-dried bone allograft (DFDBA) is widely used in periodontal regeneration procedures as a scaffold for new bone formation in periodontal defects. How this biomaterial alters osteoblast activity to promote bone formation is poorly understood. We therefore attempted to address this question by using microarray techniques to identify genes that are differently regulated in osteoblasts exposed to DFDBA. By using DNA microarrays containing 20,000 genes, the authors identified in an osteoblastlike cell line (MG-63) cultured with DFDBA (Allogro, Dentsply/Friadent- Ceramed) several genes whose expression was significantly up-regulated or down-regulated. The differently expressed genes cover a broad range of functional activities: (1) cell cycle regulation, (2) immunity, (3) vesicular transport, (4) production of cytoskeletal elements, and (5) bone remodeling. The data reported are, to the authors' knowledge, the first genetic portrait of DFDBA effects. They can be relevant to a better understanding of the molecular mechanism of bone regeneration and as a model for comparing other materials with similar clinical effects.

The achievement of optimal esthetics around anterior dental implants has been a major challenge for many clinicians. The key to an esthetically pleasing appearance lies in the clinician's ability to properly manage the soft tissue profile around dental implants. Hence, the purpose of this case report is to describe a new technique that uses the patient's own natural tooth for the provisional implant restoration to develop soft tissue architecture that is almost identical to the patient's original immediately after tooth extraction. Ten consecutively treated patients were included in this series. Clinical measurements included soft tissue height, papilla appearance, and probing pocket depths. Other parameters such as radiographic bone levels and quality-of-life ratings were also recorded. Results from this study showed that all patients achieved a normal or Class 1 papilla appearance similar to the original appearance of the natural tooth. All patients were very happy with the treatment outcome. This newly suggested approach for restoring an anterior implant can be valuable and esthetically pleasing.