The International Journal of Oral & Maxillofacial Implants, 06/1995

In this study, the primary culture of bovine mandibular osteoblast cells in a microculture assay has been used to further investigate the interaction of mineralizing osteoblast cultures with implant surfaces by using correlative microscopic techniques. Rapid differentiation and mineralization of osteoblast cultures grown on titanium alloy surfaces was observed. The successful short-term culture of mineralizing mandibular osteoblasts on titanium alloy surfaces occurred without the formation of a tenacious adhesive interface between the alloplastic material and the multilayered cell culture. Keywords: cell culture, dental implant, interface, osteoblast, titanium alloy

In the present histologic study of the mandibles of five foxhounds, 15 nonsubmerged titanium implants were placed in bone regenerated in extended membrane-protected defects during a 6-month healing period. The clinical and radiographic evaluation demonstrated that all 15 implants achieved functional ankylosis within 3 months following implant placement. Subsequently, eight implants were restored with fixed partial dentures and were functionally loaded for 6 months, and seven implants were left unrestored. At the completion of the study, the histologic analysis demonstrated osseointegration with direct bone-to-implant contact for all 15 implants. Therefore, it can be concluded that bone regenerated in membrane-protected defects responds to implant placement like nonregenerated bone, and that this bone is capable of bearing and sustaining functional load. The histologic comparison of restored and unrestored sites demonstrated no apparent differences concerning bone remodeling activities. Furthermore, control sites without implant placement demonstrated bone atrophy underneath the membranes with a thin cortical layer and sparse bone trabeculae. Thus, it can also be concluded that the placement of an implant into regenerated bone stimulated bone maturation and bone remodeling, whereas implant loading did not influence bone remodeling in the present study model. Keywords: bone defects, bone healing, dental implants, guided bone regeneration, membranes, occlusal load, osseointegration

The purpose of this investigation was to clinically evaluate the modified method for surgical rehabilitation of severely atrophied maxillae with titanium implants. In 35 patients, sinus lift, Le Fort I osteotomy, and a down-tilting of the maxilla were performed. Bone grafts from the iliac crest, placed between the sinus mucosa and the sinus floor, were secured with three to four Bränemark titanium implants 10 to 20 mm in length on each side. The osteotomized maxilla was stabilized with miniplates. The observation period was between 1 and 4 years after abutment connection. The rate of successful osseointegration was 86.6%. Keywords: atrophic maxilla, bone graft, Le Fort I osteotomy, osseointegrated implant, sinus mucosa

In the edentulous patient with a completely implant-supported prosthesis, periodontal ligament receptors are absent. However, the implant patient's mandibular function during mastication and clenching is significantly improved and can be similar to that of dentulous subjects. The underlying mechanisms that govern this proprioceptive control are not well understood. One possibility that has been explored only partially is that residual axonal elements in the peri-implant region may have a proprioceptive function. To survey the peri-implant region for axonal elements, this study utilized immunohistochemistry with neurofilament as the marker. Histologic sections of the peri-implant area from 12 implants placed in the mandibles of three dogs were examined for the presence of neurofilament. Two to three labeled sites per section in the peri-implant region were commonly found. However, the functional significance of these axons must be further evaluated before any conclusions regarding their role in proprioception can be made. Keywords: bone connective tissue, dental implants, immunohistochemistry, neurofilament, proprioception

Diseased implants can be distinguished from healthy implants by the presence of inflammation in the surrounding tissue. Inflammation correlates with elevated levels of interleukin-1ß in gingival crevicular fluid. An analysis of interleukin-1ß levels in diseased implants compared to those in matching healthy implants in 12 patients indicates that the level of interleukin-1ß was approximately three times that at healthy sites. Interleukin-1ß levels may provide a means of monitoring the health status of dental implants. Keywords: cytokines, implants, interleukin-1ß, peri-implantitis

Fifty-seven patients were followed for 2 years and 34 patients for 3 years in a study of the CeraOne system. One implant was lost, resulting in a cumulative success rate of 97.3% at the 3-year examination. All-ceramic crowns were seated for 95% of the subjects, and only four of the crowns were classified as failures. Two all-ceramic crowns fractured following trauma, but no crown was fractured when exposed to common bite forces. The bone loss around implants and adjacent teeth was small, and few problems were observed. It was proven that the system achieves good esthetic results and avoids the complications of screw loosening and fistula formation. Keywords: ceramic crown, CeraOne, single-tooth implant

Although the use of hydroxyapatite-coated (HA-coated) endosseous implants in the treatment of dental patients has been established, their clinical predictability remains controversial. This study is an analysis of the clinical predictability and indications for use of HA-coated endosseous implants. This study also discusses the biochemical composition of commercial HA coatings in relation to in vivo predictability, potential concerns, and potential advantages of HA coatings. Clinical studies suggest that HA-coated implants have short-term survival rates (ranging from 6 months to 6 years) that are comparable to short-term survival rates of titanium implants. In addition, clinical data suggest that HA-coated implants may be valuable treatment modalities when placing implants (1) in type IV bone, (2) in fresh extraction sites, (3) in grafted maxillary and/or nasal sinuses, or (4) when using shorter implants (less than or equal to 10 mm). However, long-term controlled studies are required to validate these observations. Keywords: clinical predictability, endosseous implants, hydroxyapatite coatings

The objective of this study was to determine if the biologically active molecules laminin and fibronectin could influence gingival cell attachment to implant surfaces in vitro. Flat squares of the following implant materials were tested: smooth, plasma-sprayed, and hydroxyapatite-coated titanium. The surfaces were coated with equimolar quantities of either laminin, fibronectin, or bovine serum albumin. Fibronectin coating of implant surfaces resulted in two to three times the enhancement of gingival fibroblast binding on all implant surfaces tested (P .01), with a lesser effect on epithelial cells. Laminin coating resulted in three to four times the enhancement of gingival epithelial cell binding on all implant surfaces tested (P .01), with a lesser effect on fibroblasts. The two cell types exhibited distinct preferences for the different molecules tested with the surface roughness having some influence. Keywords: attachment, epithelium, fibroblast, fibronectin, implant, laminin

Four biomechanical parameters-peak force, vertical displacement, interface stiffness, and strain energy-were defined to evaluate bone-implant interface properties. These parameters were measured at placement and after 3 months of healing during push-in tests on commercially pure titanium implants placed in the mandibles of dogs in a one-phase nonsubmerged procedure. Comparison of the results showed that peak force, interface stiffness, and strain energy increased after 3 months of healing, but vertical displacement decreased. These findings suggest that the interface stiffness, which is considered a major factor for implant success, increases during 3 months of healing in dogs, which corresponds to a 4- to 6-month healing period in human mandibles. Keywords: bone implant interface, compressive peak force, healing, interface stiffness, titanium screw implants

Failure to osseointegrate traditionally mandates immediate implant removal, followed by a 1-year healing period before placing a second implant into the same area. This report presents five cases in which failed screw-type, commercially pure titanium implants were immediately replaced by ledge-type, hydroxyapatite-coated, Ti-6Al-4V implants in the same sockets. These cases suggest that the 1-year healing period may not be necessary, provided that (1) the socket can be reprepared to eliminate thread grooves and invasive soft tissue, (2) the replacement implant is larger in diameter than the original implant, and (3) sufficient available bone remains for the procedures. Keywords: hydroxyapatite-coated implant, ledge-type implant, screw-type implant, titanium implant

This study reviews the long-term outcome of overdenture treatment in 64 completely edentulous patients who received 218 one-stage ITI implants during the period 1982 until 1988. The evaluation time averaged a period of 80 months, ranging from 66 to 119 months. The results indicate that no implants were lost during this period and that a minimum of surgical and prosthetic treatment was necessary to maintain the overdentures. Patient satisfaction was high and had not significantly changed in comparison with an earlier study on the same group of patients after a mean period of 18 months. The assumption that there would be significantly more complaints about retention of the maxillary denture is not affirmed by this study. Keywords: dental implants, overdentures, patient satisfaction

Healthy human periodontal and peri-implant (ITI Bonefit) keratinized gingival tissues were studied immunohistochemically to evaluate the possible presence of structural differences in the extracellular matrix protein localization. Collagen types I, III, IV, and VII and fibronectin showed similar distribution in these tissues. Compared to the periodontal tissues, collagen type V was localized in higher amounts in the lamina propria of the peri-implant gingival tissues. Collagen type VI stained the periodontal tissues as a delicate microfibrillar network contrasting to the not well-stained peri-implant gingival tissues. The data show that structural differences between these tissues are present. The structural differences may be responsible for the defense of peri-implant keratinized gingival connective tissues to bacterial penetration, because of the high amount of the collagen type V component, which is responsible for the higher collagenase stability. Keywords: collagen, extracellular matrix, fibronectin, gingiva, peri-implant soft tissues

Treatment of edentulous patients who have temporomandibular disorders is difficult because of the poor stability of their conventional complete dentures. With an implant-supported bar and a clip-to-bar overdenture, mandibular dentures can be stabilized. The results of a prospective clinical study of 10 edentulous patients with temporomandibular disorders and treatment with implant-supported overdentures in mandibles are presented. Before and after 3 years of wearing the implant-supported overdentures, patients were interviewed and a clinical functional analysis was taken. Patients with displacement of the articular disc or bone destruction of the joints had a decrease in pain, an enhanced mobility of the mandible, and a decrease in temporomandibular joint sounds. Patients with pain of muscular genesis as a result of bruxism suffered after 3 years from the same pain and did not show an improvement of muscle or joint sensitivity. Keywords: edentulous patients, implant supported overdentures, temporomandibular disorders

Root-form titanium dental implants are the treatment of choice for many partially and totally edentulous patients. The overall success rate is greater than 95%. Postoperative pain is usually the result of infection. This report presents two cases involving a sudden onset of jaw pain. Computerized tomographic scanning revealed that the pain was caused by stress fracture of the mandible. Keywords: dental implants, fracture, nuclear bone scanning