Showing papers in "Implant Dentistry in 1999"

Maxillary sinus membrane repair: report of a technique for large perforations.

Abstract: Maxillary sinus membrane perforation is the most common complication that occurs with the sinus elevation augmentation procedure. Repair of relatively small (5-10 mm) tears is commonly done using fast resorbing collagen membranes and/or by allowing the sinus membrane to overlap on itself. A technique using a cross-linked type I collagen membrane for predictable repair of large perforations (> 10 mm) as well as for circumstances in which no membrane is found is described. This technique has several advantages because of its inherent biologic properties.

Why do dental implants fail? Part II.

Abstract: Many factors are attributed to failure of the dental implant, either directly or indirectly. The focus of this article is to define the causation of dental implant failure, as well as to present an evaluation of the implant literature regarding etiology, classification, management, and treatment of implant failures. This article will highlight the initial signs of implant failure with a view of some clinical cases in terms of classification and degrees of implant failure. Finally, a dental implant failure checklist is formulated to guide the practitioner in defining the cause of implant failure, be it infective or noninfective, and to establish percentages and frequency of occurrence. The checklist applies to all implant systems and will help to determine the factors responsible for causation and the repair procedures, whether they are at the surgical or restorative phases. The definition of implant failure is set forth in terms of ailing, failing, failed, and surviving implants, and the appropriate treatments and dispositions are outlined.

Block autografts for localized ridge augmentation: Part II. The posterior mandible.

Abstract: The posterior edentulous mandible presents unique challenges for implant reconstruction because of deficiencies in bone quality and quantity Autogenous mandibular block grafts can be used in a predictable manner to enhance bone volume and density, allowing for placement of maximum diameter implants to facilitate stress distribution for long-term implant survival This article will feature the importance of staging and recipient site preparation using mandibular block autografts for posterior mandibular edentulous reconstruction

Augmentation grafting of the maxillary sinus for placement of dental implants: anatomy, physiology, and procedures.

Abstract: In patients with an inadequate amount of bone for implant placement, sinus lift surgery can be performed to restore a sufficient amount of alveolar bone to allow for successful implant placement and subsequent prosthetic reconstruction. In this article, the anatomy and physiology of the maxillary sinus, the mechanisms of bonegrafting, bone grafting material, preoperative evaluation, surgical technique, and the grafting procedure, as well as intraoperative bleeding and postoperative complications, are discussed. (Implant Dent 1999;8:36–46)

Implant design considerations for the posterior regions of the mouth.

Abstract: The posterior regions of the mouth sustain greater forces, yet often present poorer bone density. A biomechanical approach, often presented to decrease risk factors in such regions, is to increase implant surface area. Most manufacturers provide implants in various lengths. The longest implants are typically inserted into the anterior regions of the mouth, where forces of less magnitude and superior bone quality are present. A finite element analysis supports the hypothesis that implant length is a secondary parameter for stress distribution. A common approach is to enhance implant surface area in the posterior regions primarily by focusing on diameter. However, this increases surface area by only 30% for conventional thread designs despite the fact that forces increase by > 300% in the posterior regions. A change in implant diameter and thread design may increase surface area by > 300%. Such increases in surface area may decrease stresses to the crestal bone regions and reduce both crestal bone loss and early loading implant failure.

Dental implants in the diabetic patient: a retrospective study.

Abstract: It has become increasingly common for controlled diabetic patients to be considered as candidates for dental implants. This study reports on the results of placing implants in 34 patients with diabetes who were treated with 227 Branemark implants. At the time of second-stage surgery, 214 of the impl

In vitro stress analyses of dental implants supporting screw-retained and cement-retained prostheses.

Abstract: A photoelastic and strain gauge analysis was performed to evaluate the stress transferred to implants through the provisional-cement-retained, the permanent-cement-retained, and the screw-retained prostheses. The deflections of the prostheses at the time of the loading were also measured. In the single crown test, the provisional-cement-retained crowns transferred less stress. In the two-unit fixed partial denture test, there were no differences between the three different prostheses. In the two-implant supported distal cantilevered prostheses, the screw-type and the permanent-cement-retained prostheses developed more stress around the apex of both implants. The permanent-cement-retained prostheses acted almost the same as the screw-type.

Osseointegration of titanium metal implants in erbium-YAG laser-prepared bone.

Abstract: Titanium screws were implanted in rat calvarial defects of identical size using either a laser or bur. The aims of this study were to determine whether the screws were able to osseointegrate in a laser-prepared bone defect and to compare the pattern of bone healing around these screws. The optimal laser settings to produce a 0.7-mm-diameter hole in the rat calvaria were determined. A 0.7-mm-diameter hole was prepared on the left calvaria with the erbium-YAG laser to receive a 1-mm-diameter self-threading titanium screw. Each animal also received a 0.7-mm-diameter hole prepared on the right calvaria with a conventional metal bur, and a 1-mm-diameter self-threading screw implant was placed. Rats were killed humanely either 3 weeks or 3 months after surgery, and the skulls were processed in paraffin wax for histological analysis. Laser-prepared defects: At 3 weeks, the screw was surrounded by vital woven bone. The dura mater was perforated, and cystic change was present in the underlying brain tissue. There was active bone formation adjacent to the screw surface, deposited on a thin zone of necrotic bone. At 3 months, the screws were osseointegrated, and the brain tissue was healed by gliosis. Bur-prepared defects: At 3 weeks, there was extensive remodeling around the prepared defect. The dura mater was intact, and there was no damage to the underlying brain. At 3 months, the screws were successfully osseointegrated with bone adjacent to the screw. Osseointegration of titanium screws can be achieved using an erbium-YAG laser to prepare the implant bed.

Implant support for removable partial overdentures: a case report.

Abstract: Functional stability and the preservation of remaining alveolar bone are primary, and often elusive, goals when restoring the partially edentulous arch. The incorporation of dental implants for the partial support of removable prostheses offers a practical adjunct in the fulfillment of these objectives. Planning for complex courses of treatment that include dental implants requires close coordination between the surgeon and the restorative dentist. Decisions that deal with type, location, size, number of implant fixtures, and design of the prosthesis are critical. All of these areas must be discussed and established as acceptable to the patient and each clinician before the initiation of treatment. In this report, we present a course of patient treatment in which a removable partial denture is supported by natural remaining teeth in conjunction with osseointegrated implants.

Histomorphometric analyses of hydroxyapatite-coated and uncoated titanium dental implants in rabbit cortical bone.

Abstract: In this article, we report the results of analyses of bone healing around four types of dental implants. Five implants of each type were inserted into the proximal tibia metaphysis of adult New Zealand rabbits and were analyzed using computerized histomorphometry 12 weeks after implantation. Hydroxyapatite-coated implants showed more direct bone contact and more lamellar bone in the threads than the titanium implants. There was a significant correlation between an increase in the percentage of mineralized tissue in the threads of metallic implants and cellular density around the implant, indicating less lamellar bone in contact with metallic implants.

Improvement of osseointegration of titanium dental implants by a modified sandblasting surface treatment: an in vivo interfacial biomechanics study.

Abstract: To study the effects of a modified sandblasting surface treatment on the osseointegration of dental implants at the level of interfacial biomechanics, an in vivo pullout test was conducted using bone-interfacial shear strength as a criterion. Titanium implants were inserted into the medialis condyli of dogs and harvested 2, 4, and 12 weeks after insertion. Shear strength was determined with an Instron pullout tester. Observation and analysis of the surface of modified sandblasted implants after pullout at 12 weeks were performed with scanning electron microscopy and x-ray spectroscopy. Results showed that the shear strength of implants with a modified sandblasted surface was about five times as high as that of implants with a smooth surface. We concluded that the rough surface of titanium dental implants created by the modified sandblasting treatment can greatly enhance the shear strength at the dental implant-bone interface and that, with this enhancement, the secondary micropores play a much more important role in implant-bone bonding.

Potential of recombinant human bone morphogenetic protein-2 in bone regeneration.

Abstract: Recombinant human bone morphogenetic protein (rhBMP-2) has been used as a bone substitute. This article describes the rhBMP-2 structure, mechanisms of action, carriers, advantages, safety, and recent clinical studies relevant to dentistry.

Study of the effect of using mini-transitional implants as temporary abutments in implant overdenture cases.

Abstract: In an attempt to improve patient satisfaction during the healing period after placement of implants, mini-transitional implants (MTIs) have been advocated to allow immediate use of temporary dentures and to prevent transmucosal loads over the definitive implants. Twelve edentulous patients received two screw implants each in the predetermined mandibular canine region. At the time of surgery, six patients had two MTIs placed medially to the permanent ones. The flap was repositioned allowing transmucosal penetration of MTIs. Patients left the operating room wearing their relined lower dentures. The results indicated that MTIs integrated sufficiently in bone, giving successful immediate support for the transitional prosthesis and allowing proper mucosal healing. Two of these transitional implants showed mobility three months after phase I surgery. After loading the final implants, patients who had MTI-supported dentures showed bone loss that was not significantly different from the control group.

Punch technique for preservation of interdental papillae at nonsubmerged implant placement.

Abstract: Surgical flap procedures currently used for the placement of endosseous implants often can result in damage to the interdental papilla with subsequent poor esthetics. A simple technique is presented whereby the implants are placed by using a tissue punch and without raising a full thickness flap. At no time is the subperiosteal soft tissue flap raised, and the integrity of the interdental papilla is never disrupted. There is no discontinuation of the alveolar blood supply of the surrounding osseous tissue. In the authors' experience, there has been a significant reduction in postoperative discomfort. It is proposed that this technique warrants further evaluation, especially to compare the rate of bone resorption, because it is hypothesized that because of lack of discontinuation of the blood supply, there might be reduced bone resorption compared with conventional flap procedures.

New bone formation after a sinus lift procedure using demineralized freeze-dried bone and tricalcium phosphate.

Abstract: A mixture of demineralized freeze-dried bone and beta-tricalcium phosphate was used for bone augmentation in a sinus lift procedure. Hydroxyapatite-coated implants were placed in the newly formed bone-like material before prosthetic reconstruction. A biopsy specimen taken at 16 months showed that the bone-like material was composed of normal lamellar and woven bone.

Esthetic considerations in anterior single-tooth replacement.

Abstract: Anterior single-tooth replacement is the ultimate challenge facing the prosthodontist or the restorative dentist Use of dental implants as a modality of treatment has overcome the disadvantages of conventional restorative techniques Implantologists aim at creating an implant-supported restoration that replicates natural teeth This article focuses on the different techniques that enhance maximum esthetic outcome of implant-supported anterior tooth restorations at the different stages of treatment In addition, it discusses one of the problems in esthetic implant dentistry, prosthetic-driven implant placement versus available-bone-driven implant placement

Evaluation of the effects of restorative materials used for occlusal surfaces of implant-supported prostheses on force distribution.

Abstract: In this study, the functional stresses in alveolar bone created by restorative materials used in implant-supported prostheses were determined by the photoelastic stress analysis method. A photoelastic resin mandibular model, hollow-cylinder implants (3.5 mm diameter, 10 mm length), and fixtures and superstructures made of five different prosthetic materials were used. Vertical and 45-degree inclined loads were applied to the model. Subsequently, color photographs of the force line distribution observed on a polariscope were taken. Differences between vertical and inclined loads were statistically significant for all prosthetic materials (P < 0.01). The greatest stress distribution around the apex of the implant was observed with Ceramco II porcelain, followed by Biodent acrylic. The ArtGlass and Elcebond CCV composite materials had equal values, whereas Verebond Ni-Cr alloy showed minimum stress distribution.

Use of a tapered, porous-surfaced dental implant in combination with osteotomes to restore edentulism in the difficult maxilla.

Abstract: The maxilla is the more difficult arch to restore with endosseous dental implants because of hurdles such as low bone density, narrow buccopalatal width, minimal bone height, and proximity to the maxillary sinus. In this article, a technique to resolve all of these problems using a short, tapered, porous-surfaced implant and a placement protocol using hand osteotomes rather than surgical burs is presented.

Localized ridge maintenance using bone membrane.

Abstract: The immediate placement of a dental implant into a fresh extraction socket has been limited in many instances by the quantity of bone that remains after the extraction. This article presents two clinical cases that demonstrate successful regeneration of alveolar ridges in which there was extensive loss of the buccal plate of bone. This lack of alveolar process impeded the immediate placement of dental implants into fresh extraction sockets. The surgical technique performed in these cases was based on the principles of guided bone regeneration using a demineralized freeze-dried bone membrane. The bone membrane acted as an efficient barrier that excluded the nonosteogenic tissues. Bone formation took place for the placement of endosseous dental implants 8 months after the procedures were initiated. These human clinical cases confirm positive results of previous animal findings.

Titanium foil-guided tissue regeneration in the treatment of periimplant bone defects.

Abstract: Resorbable membranes are often not stable enough for complete corrections of deep periimplant bony defects. Nonresorbable polytetrafluoroethylene membranes require removal after osseous healing. In this study the use of titanium foils for reconstruction of deficient alveolar ridge structures around dental implants is described. The advantages and disadvantages of the titanium foil–guided bone regeneration technique is discussed. Forty-two patients with deep intra alveolar periimplant defects were treated by means of a titanium foil–guided bone regeneration technique. Autologous bone in combination with a demineralized freeze-dried bone allotransplant was used for augmentation. Clinical and radiological control was performed 3, 6, and 12 months after surgery. In 37 cases, the average 12-month postoperative increase in bone was 4.2 mm, and the decrease in augmented bone was only 4% compared with the postoperative situation. Acceptable augmentative results-were achieved in 88% of patients after the first operative treatment using a titanium foil–guided bone regeneration technique for reconstruction of periimplant defects and in all patients after the second augmentation. The main problem with foil loss was denudation and infection 6 weeks after surgery.

Protein adsorption and osteoblast responses to heat-treated titanium surfaces.

Abstract: The clinical success of dental implants is governed in part by surface properties of implants and their interactions with the surrounding tissues. The objective of this study was to investigate the effect of heat-treated titanium (Ti) surfaces on protein adsorption and osteoblast responses in vitro. The passivated Ti samples used in this study were either nonheat-treated or heat-treated at 750 degrees C for 90 minutes. Using x-ray diffraction analyses, no oxide peaks were observed on the nonheat-treated surfaces, suggesting an amorphous oxide. Crystalline rutile TiO2 peaks were observed on the heat-treated Ti surfaces. The contact angles of water on heat-treated Ti surfaces (32.0 +/- 2.5 degrees) were statistically lower compared with the nonheat-treated Ti surfaces (47.7 +/- 2.3 degrees). In addition, the mean albumin concentration on the nonheat-treated Ti surfaces (3.57 +/- 0.33 micrograms/mL) was observed to be significantly different from the mean albumin concentration on heat-treated Ti surfaces (2.25 +/- 0.26 micrograms/mL). In the presence of an osteoblast precursor cell line, significantly different hexosaminidase activity, protein production, and alkaline phosphatase activity were observed for cells grown on heat-treated Ti surfaces compared with nonheat-treated Ti surfaces.

Treatment of peri-implantitis: longitudinal clinical and microbiological findings--a case report.

Abstract: Failing implants can be successfully treated by surgical procedures that use either bone fillers or membranes combined with an antimicrobial treatment. In this report, we present a case of failing implants with the corresponding treatment and results of 8 years of follow-up.

Three-dimensional guidance system for implant insertion: Part II. Dual axes table--problem solving.

Abstract: The three-dimensional guidance system for implant insertion is a technique for placing a radiopaque vertical orientation pin over the crest of the alveolar ridge on the stone cast during fabrication of the radiographic guide. The cross-sectional and panoramic reformatted images were reproduced on a Polaroid or 35-mm print. The true vertical orientation pin facilitates (1) identification and the exact planned location of each implant in the reformatted images of the CT scan, (2) establishment of the internal starting point for the osteotomy on a photographic print, (3) optimum implant orientation, and (4) measurement of the angulation between the true vertical orientation line and optimum implant orientation. With the aid of a newly developed dual-axes base and transfer of the internal starting point of each implant to the stone cast, the buccolingual and mesiodistal implant inclinations for each implant were transferred to a surgical guide in the form of surgical steel drill guide tubes. The resulting pilot osteotomy transfers to the alveolar bone the exact starting point and the buccolingual and mesiodistal inclination for each implant. The technique provides a three-dimensional guidance system for implant insertion that is extremely accurate and yet practical.

Restoration of congenitally missing lateral incisors: a case report.

Abstract: Parents and dentists are forced to make a decision early in a young patient's life when it is learned that the lateral incisors are missing. For many years the treatment has been to either move the cuspids into the lateral incisor sites or retain the teeth in their natural environment and restore the defect with a bonded or fixed bridge. With the advent of new designs in dental implants and their abutments, it is possible to consider replacing missing single teeth with implant-borne prostheses. Often-times, because of the limited residual bone and proximity of adjacent roots, placing conventional cylinder or screw-type implants is difficult. This article demonstrates the advantages of using a tapered-step implant, immediate one-stage surgery, and temporization in replacing congenitally missing laterals.

Evaluation of bone tissue on metallic implants by energy-dispersive x-ray analysis: an experimental study.

Abstract: Osseointegration capacity of the different metallic implants depends on several variables Osseointegration can be evaluated by using different methodologies, such as light microscopy and scanning or transmission electron microscopy The aim of this study was to develop a qualitative and quantitative method to evaluate the presence of bone tissue on large metallic surfaces A laminar implant was placed in each tibia of 10 Wistar rats The animals were killed 30 days after surgery Tibiae were resected, one for embedding in methyl methacrylate and the other for evaluation by energy-dispersive x-ray analysis Light microscopy revealed osseointegration Observation of the implant surface by scanning electron microscopy revealed the presence of a coating on the metallic surface that was rough in some areas and smooth in others Analysis of the coating by energy-dispersive x-ray analysis showed the presence of Ca and P Eighty percent (+/- 10%) of the metallic implant surface exhibited bone tissue After confirmation of the occurrence of osseointegration capacity using light microscopy, the method described here allows qualitative and quantitative evaluation of the bone tissue found on large metallic surfaces

Fixed prosthodontics in skeletal Class III patients with partially edentulous jaws and age-related prognathism: the basal osseointegration procedure.

Abstract: Today, prognathism in the partially or completely edentulous jaw can be treated with endosteal implants and fixed prostheses. The preferred procedure uses basal osseointegration. If the distribution of available bone is favorable, the prosthodontic suprastructures can be loaded early, taking the various phases of bone regeneration into account. Invasive surgical interventions, specifically iliac crest transplants, are rarely indicated and can be avoided in most cases. Patients are able to return to their everyday lives within a few days.