International Journal of Periodontics & Restorative Dentistry, 02/1997

The condylar path, the incisal path, and the cusp angle determine the amount of disocclusion during eccentric movement. In prosthodontics, the condylar path has been used as the main determinant of occlusion. However, the method to derive the incisal path and cusp angle from the condylar path is not known, and thus it has been difficult to scientifically reproduce the amount of disocclusion on a restoration. This study describes the Twin-Stage Procedure, in which the cusp angle is used as the main determinant of occlusion because of its reliability. It is possible to accurately control the amount of disocclusion on the restoration without measuring condylar path.

This two-center human clinical trial evaluated recombinant human bone morphogenetic protein-2 delivered in an absorbable collagen sponge (rhBMP-2/ACS) for either alveolar ridge preservation after tooth extraction or augmentation of localized osseous defects. This 24-month study comprised two parts: a 4-month acute safety and bone induction period (Part I) followed by a 20-month, osseointegration, functional restoration, and long-term safety evaluation (Part II). The primary objective of Part I, discussed in this article, was to evaluate the short-t erm safety and technical feasibility of the rhBMP- device implantation. Twelve patients (six preservation and six augmentation) were enrolled in the investigation. Patient safety was monitored by oral examinations, radiographs, and the collection of blood samples to measure serum chemistries, hematology, and potential antibody formation. Technical feasibility was evaluated by collecting information relating to the handling properties of the rhBMP-2/ACS device. The ability of various evaluative tools to measure the bone-inducing activity of the rhBMP-2/ACS device was also assessed. The clinical results suggested that rhBMP-2/ACS was well tolerated locally and systemically, with no serious adverse events. The device was found to be easily handled and adapted to the r idge and extraction socket. Using direct measurements, all sites demonstrated firmness and fullness to palpation at 4 weeks; however, a loss of volume was noted in some treatment areas betwen 4 and 8 weeks. Augmentation of the alveolar ridge was not observed in the patients as assessed by the evaulation techniques. This trial indicated that the use of rhBMP-2/ACS to rpeserve alveolar ridge after tooth extraction or augmentation of localized defects is safe and feabile. Bone fill was observed in all alveolar sockets filled with the rhBMP-2 device.

Guided bone regeneration procedures around immediately placed implants may result in well-osseointegrated fixutres, but because of complexed flap manipulation, the functional, phonetic, and esthetic result may be unsatisfactory, especially when performed in the maxillary anterior region of the mouth. For better results a modified ridge preservation technique, called socket seal surgery, which combines bone and soft tissue grafting and is performed prior to implant placement has been suggested. A novel approach is presented in which socket seal surgery is performed simultaneously with implant placement to achieve optimal replacement of an extracted maxillary anterior tooth.

Osseointegration is a histometric process that occurs gradually over a period of time. The load that an implant is able to bear depends upon, among other parameters, the quality of the bone-implant contact. For 8 years the damping capacity of 1,182 Branemark implants inserted consecutively in 315 patients was measured using the Periotest method. The following clinical observations were made: (1) a relationship was found between implants with a specific Periotest value range that, at the moment of the transepithelial connection, were considered to be clinically stable, asymptomatic, and whose radiograph image was not radiolucent; (2) a relationship was found between clinically nonintegrated implants with a different Periotest value range; (3) variations in the Periotest value were related to the type of bone in which the implant was placed; (4) a small percentage of borderline implants with a Periotest value between the osseointegrated and the nonosseointegrated Periotest values was detected; (5) the percentage of secondary failures was related to an initial Periotest value corersponding to a borderline implant; (6) the healing time of each implant was individualized in accordance with the successively obtained Periotest value; (7) the load and the design of the prosthesis were individualized; (8) early detection of failing implants before fabrication of prostheses is possible; (9) communication was improved between the surgeon and the prosthodontist; and (10) variations in Periotest value wre related to bone remodeling. The sensitivity of the principal clinical test in evaluating osseointegration is dicussed regarding the moment of its application. The use of Periotest values as an initial success criteria of an implant is proposed.

This pilot study analyzed the bone reactions to early loaded titanium plasma-sprayed implants. A total of 24 titanium plasma-sprayed implants (12 in the maxillla and 12 in the mandbile) (Primary Healing Implant, Legnano) were inserted into four Macaca fascicularis monkeys with instruments specially designed to obtain a precise fit of the implant in the bone socket. A metal superstructure was cemented into 10 mandibular and 10 maxillary implants 15 days after implant insertion. The four remaining implants were used as controls. Eight months after implant placement, a block section was carried out, the defect was filled with nonresorbably hydroxyapatite, and all 24 implants were retrieved. The implants were treated to obtain thin ground sections that were examined under normal and polarized light. Histologic analysis showed that bone was observed around the implant surface in all implants. Morphometric analysis demonstrated that bone lined 67.2% (SD = 3.1%) of the maxillary implant surface, and 80.71% (SD = 4.6%) of the mandibular implant surface. No differences were found in the percentage of bone-implant contact in the control implants. In the loaded implants, however, the bone around the implants had a m ore compact appearance. The study demonstrated that it is possible to obtain a high percentage of bone-implant contact in early loaded titanium plasma-sprayed implants.

This study evaluated a new surgical technique for the treatment of an alveolar ridge deficiency in 11 patients. Twenty-two implants were placed, 15 of which presented with a combination of supracrestal and dehiscence kinds of defects, and seven presented only supracrestal bone loss. Surgical procedures were performed utilizing a combination of the resorbable spacemaking material calcium carbonate stabi lized with a fibrin-fibronectin sealing system and the immediate placement of titanium dental implants. After implant placement, the mean height for supracrestal and dehiscence defects measured 2.57 ± 1.41 mm and 2.47 =- 1.54 mm, respectively. The defects were filled with calcium carbonate and a fibrin-fibronectin sealing system, and the flaps were sutured, avoiding any compression of the treated area. Healing was uneventful in all instances. At second-stage surgery at 6 months, a hard bonelike tissue was detectable at the defect sites. Histologic examination of four defects confirmed the presence of newly formed bone and revealed residual particles of calcium carbonate. There was a mean gain of 2.05 ± 1.47 mm in the supracrestal defects and of 2.23 ± 1.62 mm in the dehiscences. The results indicated that calcium carbonate, combined with a fibrin-fibronectin sealing system, is a viable alterantive in the treatment of supracrestal and dehiscence bony defects

Two case reports illustrate spontaneous correction of pathologic migration following periodontal therapy. In one case, the displaced teeth were repositioned without orthodontic appliances after nonsurgical and surgical peridoontal treatment. In the other case, closure of a diastema occurred following only nonsurgical therapy. The predictability of these findings needs further investigation. A discussion of possible reasons for this type of tooth movement is included.

The purpose of the rpesent study was to compare tooth mortality of root-resected molars with that of root-filled, single-rooted teeth. Survival rates were 68% for root-resected molars and 77% for root-filled single-rooted teeth over a 10-year period. This difference was not statistically significant. Ten-year survival of root-r esected molars in patients with radiographic attachment loss in single-rooted teeth of greater than 6 mm was 56%, while survival was as high as 89% for root-resected molar patients with radiographic attachment loss in single-rooted teeth less than or equal to 6 mm. In conclusion, the prognosis of root-resection is not poorer than the prognosis of single-rooted teeth with an equal susceptibility to periodontitis, if endodontic conditions and maintenance care are optimal.