The International Journal of Oral & Maxillofacial Implants, 06/1996

The high resorption rate of nonvascularized bone grafts can be appreciably slowed with the use of endosseous implants and implant-supported prostheses. In cases of extreme atrophy, graft fixation with implants is hardly possible. Especially in the presence of compromised overlying soft tissues, the consolidation of such a graft can also present problems. Improved results can be obtained through use of revascularized bone grafts. Such a method using an anastomosed fibula graft to augment the maxilla is illustrated by a clinical case. After harvesting the graft, the side to come into contact with the alveolar crest is denuded of periosteum, and cuneiform ostectomies are made into the graft to facilitate its adaptation to the maxillary arch. The graft is anastomosed to the facial vessels through an intraoral route and can be placed in such a way as to simultaneously correct any existing crossbite. In contrast to an iliac graft, the implants can be placed bicortically in a fibular graft. Keywords: bone graft, implant, ridge augmentation

A dynamic modal testing technique has been developed to noninvasively assess the interface surrounding an endosseous dental implant with a lateral tap from an impedance head hammer. The technique assesses the rotational stiffness of the interface based on the shape of the power spectrum of the force-time curve produced on impact. In vitro experiments were performed to determine the sensitivity of the technique for detecting clinically relevant structural differences between interfaces. The modal test data were able to distinguish interfaces based on the type of bone at the interface and the degree of fixation between the implant and the interface. Keywords: dental implant, interface, noninvasive assessment

Resorbable membranes of poly(lactic acid) and poly(glycolic acid) (PLA/PGA) were compared to nonresorbable expanded polytetrafluoroethylene (e-PTFE) membranes in the treatment of defects around titanium dental implants placed in postextraction sockets. Two partially edentulous and three completely edentulous patients requiring implant-supported restorations participated. Sixteen Brånemark implants were placed into extraction sockets and covered with modified titanium cover screws, called harvest cover screws, which allow tissue biopsy at second-stage implant surgery. Seven defects were treated with PLA/PGA membranes, five were treated with e-PTFE membranes, and four were left untreated (control sites). After 6 months of healing, the harvest cover screws were retrieved and processed for light microscopy examination together with the regenerated tissues. Very little or no bone formation was detected in control specimens. The e-PTFE membranes were found to be the most effective barrier material, in that denser and a greater amount of regenerated bone was found. The PLA/PGA membranes produced some bone regeneration when compared to control sites, but to a lesser extent compared to e-PTFE sites. Keywords: dental implant, expanded polytetrafluoroethylene membrane, guided tissue regeneration, poly(glycolic acid) membrane, poly(lactic acid) membrane

The purpose of this study was to investigate the impact of a modified surgical protocol and the survival of implants placed in the posterior maxilla. Forty-two implants were placed in the maxillary posterior area of 29 partially edentulous patients (17 men, 12 women; mean age 50 years; range 38 to 62 years) according to the modified surgical protocol. Twenty-nine of these implants had been placed into the maxillary tuberosity. All implants were checked radiologically every 12 months with a customized film holder. The restorations were fixed partial prostheses. Only 1 of the 42 implants was lost at stage 2 surgery. Results suggest that considerable benefits may be obtained by modifying a standard surgical protocol to maximize the results for a particular anatomic site. Keywords: fixed partial prosthesis, maxillary tuberosity, modified surgical protocol, standardized radiographic follow-up

A retrospective review of a limited number of adolescents with implants was conducted to compare the behavior of these implants with studies in which implants had been placed in growing animals. Growth of the facial skeleton is also reviewed. Implants placed in the growing alveolus behave like ankylosed teeth and become submerged as the surrounding bone grows. Cessation of facial growth should occur prior to implant placement in adolescents. Keywords: adolescent, ankylosis, growth, implant, submersion

This prospective study reviews the early outcomes of 223 consecutive Brånemark implants placed in 78 patients by one operator. Patients were divided into three groups: nonsmokers (NS); smokers who followed a smoking cessation protocol (SQ); and smokers who continued to smoke (SNQ). There was a statistically significant difference between failure rates in the NS and SNQ groups (P .005) and between the SQ and SNQ groups (P .05), but none between the NS and SQ groups. It is concluded that the smoking cessation protocol described shows considerable promise in improving success rates for osseointegration in smokers who follow it. Keywords: implant failure, risk factor, smoking, smoking cessation benefits

This study presents the results of 10 consecutive patients treated with unilateral bone augmentation of the maxillary sinus floor using particulated mandible harvested from the symphysis. Endosseous titanium implants (Brånemark) were placed 6 months after the transplant procedure. Thirty self-tapping implants were placed with a mean follow-up period of 26 months (range 12 to 46 months). Bone biopsy specimens were obtained from the donor site and the residual alveolar process at the time of grafting. A second biopsy specimen was obtained from the grafted site after 6 months of healing (at time of implant placement), and a third biopsy specimen was obtained after 12 months of healing (at time of abutment placement). Histomorphometry was performed on microradiographs using a computerized image analysis system. The bone volume fraction at the donor site before particulation was 58% ± 19%, and the volume fraction at the residual alveolar process was 45% ± 15%. The mean volume fraction of bone in the grafted area increased from 40% ± 12% after 6 months of healing to 48% ± 10% after 12 months. Histology of the retrieved bone biopsy specimens revealed normal healing and bone maturation in all samples. Keywords: bone transplant, chin graft, implant, maxilla, maxillary sinus

Astra Tech implants were used to support implant-retained mandibular overdentures for 25 edentulous patients (12 with magnet retention and 13 with stud retention). The patients were followed for 3 years, and a detailed record was kept of the extent of maintenance required after placement of the dentures. There were 64 episodes of maintenance related to the overdentures in the magnet retention group and 63 episodes of maintenance in the stud retention group. Episodic maintenance was greatest during the first year, with the magnet group having 30 episodes and the stud group 34. The number of visits required for maintenance related to both the maxillary and mandibular dentures was 117 for the magnet retention group and 86 for the stud retention group. There was no statistically significant difference in the amount of postplacement care between the two groups. Keywords: implant, magnet, mandibular overdenture, stud

Thirteen irradiated and 14 nonirradiated patients were treated after resection of a malignant oral lesion. With a follow-up period of 26 months, 3 of 48 implants in nonirradiated patients and 4 of 57 implants in irradiated patients failed. In comparison to implant-tissue-supported prostheses, exclusively implant-supported prostheses demonstrated better results with regard to soft tissue trauma and function of the prosthesis. Keywords: dental implant, oral malignancy, Procera technique, prosthetic implantology, radiation, surgical implantology

Titanium is an inexpensive metal that can be used to create custom cast restorations. Although special investment and casting equipment is needed to make titanium castings, the potential benefit of inexpensive, biocompatible, and custom restorations is significant. Porcelain can easily be applied to titanium with excellent bond strength and esthetics. Problems associated with casting roughness and fit can be corrected using electrical discharge machining. A method of diagnosis and treatment planning that evaluates the restorative space prior to implant placement and eliminates the use of machined components is presented. Keywords: cast restoration, electrical discharge machining, implant, titanium

This report describes a method for gathering information to assist in properly placing dental implants. A diagnostic template is first fabricated, incorporating radiographic markers. Radiographs of the template are obtained, and data from their study are transferred to the laboratory to facilitate the fabrication of a surgical template. This procedure has the potential to map implant sites three dimensionally. Template use can result in a greater number of implants placed in optimal positions. Keywords: dental implant, implant placement, surgical template, treatment planning

Peri-implantitis has been shown to possess clinical characteristics similar to those of periodontitis. This pilot study was conducted to determine levels of inflammatory cytokines in crevicular fluid from healthy implants and those implants affected by peri-implantitis. Fifty implants from 13 patients were examined. A clinical examination was performed, and gingival crevicular fluid samples were collected and analyzed for cytokines. Implants were categorized clinically as healthy, early peri-implantitis, or advanced peri-implantitis. Interleukin-1ß was detected in the crevicular fluid of implants in all three groups (healthy = 59.47 ± 15.55 pg/site; early peri-implantitis = 460.77 ± 35.67 pg/site; and advanced peri-implantitis = 191.10 ± 21.60 pg/site [mean ± SEM]). These results indicate that interleukin-1ß is present in implant gingival crevicular fluid and may be modulating attachment loss in implants suffering from peri-implantitis. Thus, interleukin-1ß may be used to monitor disease progression. Keywords: crevicular fluid, cytokine, peri-implantitis

Single-nerve activities were recorded in the gasserian ganglia of anesthetized cats by glass extracellular microelectrodes to determine whether sensory endings exist within the alveolar bone. Trigeminal cells responded to mechanical and/or thermal stimulation applied to the maxillary bone. Some were activated by specific kinds of fairly precise mechanical stimuli (moderate forces applied in a preferential direction); others exhibited a coarse mechanical sensitivity. In addition, electrical stimulation was applied to the maxillary bone to determine the conduction velocities of the relevant fibers. These mainly ranged between 1 and 6 m/s, which indicates that the fibers belonged to the small-diameter category (thinnest myelinated and unmyelinated fibers). Similar results were obtained from animals with osseointegrated implants. It was concluded that the alveolar bone is endowed with sensory endings capable of detecting mechanical and thermal changes, and that these receptors may provide compensatory sensitivity in edentulous subjects whose main (periodontal) sensitivity has been eliminated. Keywords: alveolar bone, cat, gasserian ganglion, microelectrode, sensory receptor

A planning system for oral implant surgery based on a true three-dimensional approach is described. This system allows the interactive placement and adjustment of axial-symmetric models representing implants in the jawbone structures visible on computerized tomographic volume data. Simultaneous visualization is possible on two-dimensional reformatted images and on three-dimensional-derived bone surface representations. This approach largely outperforms the manual planning practice based on two-dimensional dental computerized tomographic images printed or on film. Keywords: computer-assisted surgery, computerized tomography, dental implant, OpenGL, preoperative planning

The aim of this study was to report alveolar bone loss during the first 12 months after implant abutment connection. Marginal bone loss around 62 endosseous root-form implants in 62 patients was measured on periapical radiographs. Changes in bone density were measured by the digital subtraction image radiographic method. At 3-month intervals for 1 year, bone loss around the four types of implants used (standard series, mini series, and hex-lock implants of the Steri-Oss system; and 3i standard implants) was investigated. Rapid bone loss around all four implant types occurred in the first 3 months. Most of the implants showed resorption of alveolar bone beyond the polished neck at 12 months. The bone level stabilized at the first thread of the implants with no correlation to either the time of exposure of the polished neck or the type of implant. Bone density decreased at the marginal bone and increased at the newly formed alveolar crest. Keywords: alveolar bone resorption, bone density change, dental implant, digital subtraction image method