International Journal of Periodontics & Restorative Dentistry, 03/2007

In this prospective randomized controlled clinical study, small titanium implants were placed in posterior maxillae for the purpose of assessing the rate and extent of new bone development. Nine pairs of site evaluation implants were placed in posterior areas of maxillae and retrieved with trephine drills after 4 or 8 weeks of unloaded healing. The amount of bone in linear contact (%) with the implant surface was used to determine the osteoconductive potential of the implant surface. Implant surfaces were dual acid etched (n = 9) (controls) or dual acid etched and further conditioned with nanometer-scale crystals of calcium phosphate (n = 9) (test implants), and the surfaces were compared. The implants and surrounding tissues were processed for histologic analysis. The mean bone-to-implant contact value for the test surface was significantly increased over that of the control implants at both time intervals (P .01). For the implants/patients included in this study, the addition of a nanometer-scale calcium phosphate treatment to a dual acid-etched implant surface appeared to increase the extent of bone development after 4 and 8 weeks of healing.

Treatment of intrabony periodontal defects with an enamel matrix derivative (EMD) has been demonstrated, in the short term, to result in periodontal regeneration and to significantly improve clinical parameters such as probing depth (PD) and clinical attachment level (CAL). The present study evaluated deep intrabony defect sites at 9 years after treatment with EMD. Twenty-one patients with a total of 26 deep intrabony defects with PD >= 6 mm and intrabony depth >= 3 mm, as identified by probing and radiographs, were consecutively treated with EMD. PD, recession of the gingival margin (GR), and CAL were evaluated prior to treatment and at 1 and 9 years after treatment. At 1 year, mean PD was significantly reduced. At 9 years, mean PD was statistically significantly increased versus the 1-year results but still significantly improved versus baseline. After 1 year, mean GR had increased significantly; at 9 years, measurements showed statistically significant improvements compared to the 1-year results and baseline. The mean CAL changed from 10.0 ± 2.3 mm at baseline to 6.8 ± 2.3 mm at 1 year and to 7.0 ± 1.9 mm at 9 years. No treated teeth were lost during the observation period. The clinical improvements obtained following treatment with EMD can be maintained over a period of 9 years.

This prospective longitudinal 3-year study compared clinical parameters and implant success rates of removable superstructures supported by both teeth and implants in patients with treated generalized aggressive periodontitis (GAP) and of cemented, implant-retained fixed superstructures in periodontally healthy patients. A total of 17 partially edentulous patients with 54 implants took part in the study. Nine patients with treated GAP received removable superstructures according to the Marburg double crown system, and eight periodontally healthy patients received fixed superstructures. Teeth were examined 2 to 4 weeks before extraction of the nonretainable teeth (baseline) and 3 weeks after insertion of the definitive abutments. Every 3 months over a 3-year period, clinical parameters were recorded and the composition of the subgingival microflora was determined. Intraoral radiographs were obtained at baseline, just after insertion of the superstructure, and 1 and 3 years later. Both groups showed mean plaque and gingival indices below 0.43 at implants and teeth. Mean probing depths around implants increased by approximately 0.7 mm and remained virtually constant for the teeth. Mean attachment loss at implants was 0.9 mm in GAP patients and 0.5 mm in healthy patients. The morphologic distribution of microorganisms in both groups showed healthy conditions. Moderate bone loss at teeth and implants was registered. Implant success rates were 100% in the healthy patients and 97.6% in the GAP patients. No significant differences were seen in the results between the groups.

Forty patients (12 men, 28 women; mean age 44.9 ± 13.95 years) with inadequate bone volume for implant placement in either the maxilla or the mandible were scheduled for bone-grafting procedures. Bone grafts were harvested with a piezoelectric surgical device (Piezosurgery, Mectron) from 45 donor sites and grafted into recipient sites prior to implant placement. After healing of the grafted sites, 109 implants were placed. Clinical evaluations were performed to assess the size and quality of the obtained grafts, complications at the donor and recipient sites, integration of the grafts, bone quality, resorption of the grafts, and ability to properly place implants. Piezosurgery allowed precise, clean, and smooth cutting with excellent visibility. Mean graft size was 1.15 cm3 (SD 0.5), with a maximum of 2.4 cm3. The quality of the obtained grafts was mainly cortical (71%), 42 of the 45 donor sites healed uneventfully (93.33%), and 50 of the 52 grafted sites healed uneventfully (96.15%).

A crucial factor influencing implant esthetics is the color of the peri-implant mucosa. This in vitro study analyzed the effect of titanium and zirconia with and without veneering ceramic on the color of mucosa of three different thicknesses. Ten pig maxillae were used, and the palatal area was chosen as the test region. To simulate different mucosa thicknesses, connective tissue grafts, 0.5 mm and 1.0 mm thick, were harvested from three additional jaws. Defined mucosa thicknesses were created by placing the grafts under a palatal mucosa flap. Four different test specimens (titanium, titanium veneered with feldspathic ceramic, zirconia, and zirconia veneered with feldspathic ceramic) were placed under the mucosa, and the color of the tissue was evaluated with a spectrophotometer for three different soft tissue thicknesses (1.5, 2.0, and 3.0 mm). The color was compared to mucosa without test specimens, and the color difference (ΔE) was calculated. All restorative materials induced overall color changes (ΔE), which diminished with increases in soft tissue thickness. Titanium induced the most prominent color change. Zirconia did not induce visible color changes in 2.0-mm-thick and 3.0-mm-thick mucosa, regardless of whether it was veneered. However, with a mucosa thickness of 3.0 mm, no change in color could be distinguished by the human eye on any specimen. Mucosa thickness is a crucial factor in terms of discoloration caused by different restorative materials. In patients with thinner mucosa, zirconia will show the least color change.

This report describes the rehabilitation of a patient who was completely edentulous in the mandible with a removable prosthesis supported by implants on four Straumann Wide-Neck implants placed in the positions of the canines and second molars. The Cagliari modified conometry technique was developed to improve and simplify anchorage systems based on conical copings in a removable prosthesis supported by implants. The connection of the removable prosthesis to the implants is obtained by primary conical copings, which are screwed to the implants, coupled to secondary copings equipped with plastic friction devices (Arch-Friction-Soft, Dental Konos). After the secondary copings are positioned on the primary copings, the secondary copings are fixed with acrylic resin to the removable prosthesis in the mouth, with the goal of passive fit. The prosthesis produced with this method is not a classic implant-supported overdenture but is a removable prosthesis completely supported by implants that is shaped like a fixed prosthesis. This type of prosthesis is extremely stable and has modular retention (plastic friction), creating ideal conditions for oral hygiene. The stability of this type of prosthesis results in psychologic comfort and masticatory performance similar to that of a fixed prosthesis but with the hygiene, esthetics, and lower expense of an overdenture.

This paper introduces a new system for planning implant positions directly on the working cast, called the ray setting procedure. It allows clinicians to obtain, on a master cast, the correct implant positions through the correction of previously planned expected positions. The device used is the Ray Set, a machine that can be used to precisely define, on the plaster working cast of the mouth, hard and soft tissue anatomy and correlate it with an articulator and computed tomographic data from the patient. This cast is used to build an individual surgical stent that perfectly matches the teeth and soft tissues as well as a provisional or definitive implant-supported prosthesis for partially or completely edentulous patients. A clinical case is presented to explain the procedure. A definitive all-ceramic cemented and screw-retained prosthesis, fabricated from a rigid material and with passive fit, was created before implant surgery and was placed with an immediate occlusal load applied a few minutes after implant placement. The prosthesis was retained with both cement and screws so as to make removal easy for accurate finishing of the margins immediately before cementation. The prosthesis was built, before implant surgery, according to the PIP method (presurgical implant prosthesis). The ray setting procedure can be used for planning immediate or delayed loading of implants.

This study examined the clinical performance of the scalloped NobelPerfect implant in a one-stage procedure (immediate provisionalization in the esthetic zone). In 20 patients, immediate prosthetic restorations were placed on 31 NobelPerfect implants and followed for up to 27 months. Outcome variables were success rates, marginal bone levels, and Pink Esthetic Score (PES) assessed per implant. One implant failed (success rate: 96.8%). Marginal bone levels averaged 1.7 mm above the first thread and remained stable during the observation period. Mean PES ratings were 11.3 (range, 8 to 14). Survival rates, marginal bone levels, and esthetic results suggest proof of principle for the preservation of the interproximal bony lamella with a scalloped implant design.

The purpose of this study was to evaluate the percentage of bone-to-implant contact following guided bone regeneration using expanded polytetrafluoroethylene (e-PTFE) membranes and various bone fillers in a beagle dog model. A staged approach was used for initial bone regeneration of surgically created defects and subsequent implant placement in newly regenerated ridges. Three months after bilateral extraction of the mandibular premolars and first molars, rectangular, distal-extension defects that included the entire width of the ridge buccolingually were surgically created in the alveolar processes. All defects were covered with an e-PTFE membrane, and several bone fillers were placed, in a randomized fashion, under the membrane: autogenous bone, demineralized freeze-dried bone, anorganic bovine bone, tricalcium phosphate granules, and collagen sponge. One site in each animal was treated with e-PTFE barrier membrane alone as control. Following an 8-month healing period, nonsubmerged titanium implants (36 total) were placed in regenerated bone following membrane removal. Three months later, the animals were sacrificed, and nondecalcified buccolingual sections were evaluated histometrically for bone-to-implant contact. All sites demonstrated high percentages (50% to 65%) of bone-to-implant contact, with no significant differences across the various treatment groups. In addition, all tested bone fillers formed a complex that supported and maintained the osseointegrated implants in a healthy state, with no apparent signs of peri-implantitis. Using a staged approach, the present study provided histologic and histometric evidence that implants placed in entirely regenerated bone can achieve and maintain osseointegration, regardless of the type of bone fillers used.