Showing papers in "International Journal of Oral & Maxillofacial Implants in 1991"

Early failures in 4,641 consecutively placed Brånemark dental implants: a study from stage 1 surgery to the connection of completed prostheses.

Abstract: This study comprised 4,641 Branemark dental implants, which were retrospectively followed from stage 1 surgery to completion of the prosthetic restorations. The implants were placed during a 3-year period (1986 to 1988) in 943 jaws, representing 889 patients with complete and partial edentulism. The jaw and sex distribution revealed a predominance of mandibles (564/943) and females (534/943). The mean age of the patients was 57.5 years (range 13 to 88 years) at implant placement. Only 69 (1.5%) fixtures failed to integrate, and most losses were seen in completely edentulous maxillae (46/69), in which the jaw bone exhibited soft quality and severe resorption. A preponderance of failures could also be seen among the shortest fixtures (7 mm). A majority of the mobile implants were recorded at the abutment connection (stage 2) operation (48/69).

Osseointegrated implants for single tooth replacement: a 1-year report from a multicenter prospective study.

Abstract: One hundred seven dental implants were inserted to support single tooth restorations in 92 patients participating in a prospective multicenter investigation Only three implants (28%) were lost after 1 year of clinical function Most of the remaining restorations were esthetically successful by using modified components The gingival condition was healthy around the single crowns and coincided well with the clinical situation around the permanent teeth The most obvious problem experienced during the first year was related to loose abutment screws Twenty-six percent of the screws retaining crowns were retightened during the observation period, but the frequency of loose screws had a tendency to decrease as the study progressed

Periotest: an objective clinical diagnosis of bone apposition toward implants.

Abstract: Implant mobility as an indicator of failing close bone apposition is generally known. Whereas a clearly visible mobility can always be correlated with an interposition of soft tissue, the range from a clinically firm implant to just tangible implant mobility represents the actual problem zone. Thirty consecutive patients who had mandibles restored with osseointegrated implants ad modum Branemark were tested with the Periotest device for damping characteristics of the implants and the peri-implant tissues as a whole. The mean Periotest value (PTV) was -1.74. The characteristics of the mandible, the peri-implant tissue, and the abutment length are the determining factors for the PTV. Fixture length, dolder bar, and length of time in function had no significant influence on the PTV.

Mechanical aspects of a Brånemark implant connected to a natural tooth: an in vitro study.

Abstract: Mechanical in vitro tests of the Branemark implant disclose that the screw joint which attaches the prosthetic gold cylinder and the transmucosal abutment to the fixture forms a flexible system. This inherent flexibility seems to match well the vertical mobility of a supporting tooth connected to the implant. Calculations of vertical load distribution based on measured flexibility data demonstrate that the forces are shared almost equally between tooth and implant even without taking the flexibility of the surrounding bone or the prosthesis into account. The therapy of a single Branemark implant connected to a natural tooth should be considered without any additional element of a flexible nature. Mechanical tests and theoretical considerations, however, indicate that the transverse mobility of the connected tooth should be limited and that the attachment of the prosthesis to the tooth should be of a rigid design to avoid gold-screw loosening.

In vivo load measurements on osseointegrated implants supporting fixed or removable prostheses: a comparative pilot study.

Abstract: Load was measured in vivo on a single terminal abutment cylinder by means of a strain gauge technique. The clinical measurements were made on one female patient (age 62) provided with six implants in the edentulous maxilla. A fixed prosthesis was tested initially, followed by an overdenture supported by a bar connected to the implants. The results indicated that a significant force could be introduced when connecting the framework. Furthermore, measurements showed that compression/tension forces were lower in the overdenture situation. However, the preliminary data also indicated relatively higher bending moments on the implant when the overdenture was loaded.

Three-dimensional finite element stress analysis in and around the Screw-Vent implant.

Abstract: The three-dimensional finite element stress analysis method was used to determine the pattern and concentration of stresses within the Screw-Vent endosseous implant and its supporting tissues. For this commercially pure titanium implant, maximum stresses were located within the implant collar immediately below the bony crest. These stresses were at least 18 times less than the endurance limit of commercially pure titanium (259.90 MPa). Maximum stresses (19.57 MPa) in the bone were lingual to the superior portion of the collar. Previous longitudinal radiographic studies of a similar implant have revealed bone loss mesial and distal to the implant. For the Screw-Vent, mesial and distal stresses (maximum 0.38 MPa) were much lower than those buccal and lingual to the implant. The clinical significance of the stress transfer to the bone buccal and lingual to the implant has yet to be determined.

Histomorphometric studies of hydroxylapatite-coated and uncoated CP titanium threaded implants in bone.

Abstract: Threaded hydroxylapatite-coated implants of commercially pure (CP) titanium were inserted in the rabbit tibial metaphysis. Uncoated CP titanium screw implants inserted in the contralateral leg served as controls. After 6 weeks and 1 year postinsertion, the semiloaded implants were histomorphometrically analyzed. While not significant, there was more direct bony contact with the hydroxylapatite-coated implants after 6 weeks of follow-up. One year after insertion, there was significantly more direct bone-to-implant contact with the uncoated CP titanium controls.

A removal torque and histomorphometric study of bone tissue reactions to commercially pure titanium and Vitallium implants.

Abstract: Screw-shaped commercially pure (CP) titanium and Vitallium implants were inserted in the rabbit tibial metaphysis. After a healing period of 3 months, it was demonstrated that a higher torque was needed to remove the CP titanium implants (average 24.9 Ncm) compared to Vitallium implants (average 11.7 Ncm). The histomorphometric part of the study revealed more bone-to-metal contact for the CP titanium implants (average 34.7%) compared to the Vitallium implants (average 21.7%). The results obtained in this study could be explained by differences in the topography or in biocompatibility of the metals, or a combination of these two factors.

Relationship between insertion torque and removal torque analyzed in fresh temporal bone.

Abstract: Insertion torque and removal torque of fixtures were measured using human cadaver temporal bone and human living bone. The torque level for fracturing the threads of the bone was also measured. The maximum insertion torque exerted without causing a break in bone threads was 70.0 Ncm in bicortical bone and 50.0 Ncm in unicortical bone. The relationship between insertion torque and removal torque indicated a positive correlation between both sites. However, removal torque was lower than insertion torque in all measurements. The fracture points of bone threads were 77.0 Ncm in bicortical bone and 57.7 Ncm in unicortical bone by mean. Microfractures were observed mainly in the thread bases and were directed upward in the histologic specimens examined.

Mandibular deformation in subjects with osseointegrated implants.

Abstract: Relative movement and force transmission between osseointegrated (OI) implants in the premolar regions of the edentulous mandible have been measured using intraoral transducers linked to OI implants. These have shown deformations of up to 420 microns and force transmission of up to 16 N as a result of jaw movement from the rest position. Greater displacements and forces were observed in active opening and protrusion than in lateral excursions. There were wide variations from subject to subject, and while the effects of these phenomena are not known, they may be potentially harmful to the interfaces between the implants and bone and the various components of the implant superstructure.

The effect of oral topical fluorides on the surface of commercially pure titanium.

Abstract: This study investigated the risk of corrosion of titanium abutments by the accidental or unauthorized use of preventive fluorides in the mouth. Polished test pieces of commercially pure ASTM grade 1 titanium were immersed in topically used fluorides (toothpaste, gel, and varnish). They were brushed in vitro with toothpaste and gel, corresponding to the time and effect of brushing with toothpaste twice a day for 6 years and with gel once a week for 12 years. Results indicate that an aminofluoride toothpaste with low ionizable fluoride content (0.125%) used in brushing natural teeth does not cause deterioration of the titanium abutments in the same mouth if the titanium is grade 1 purity. Carefully controlled use of fluoride gel (F 1.25%) and varnish (F 2.25%) is likewise not dangerous. The mechanical abrasion caused by toothbrush bristles appears to be the main deteriorating factor for the titanium surface.

Immediate implantation of a pure titanium implant into an extraction socket: report of a pilot procedure.

Abstract: The conventional osseointegration protocol calls for waiting up to 12 months for ossification of an extraction socket to heal before placing an endosseous implant. In this study the possibility of placing a pure titanium implant directly into an extraction socket immediately after extraction was investigated. A pure titanium Nobelpharma 10-mm implant was placed into a central incisor extraction socket of a stump-tailed monkey and allowed to heal for a period of 6 months, followed by functional loading of the implant. The implant was osseointegrated on a clinical and histological level. This pilot study suggests that pure titanium implants have the potential to integrate when placed immediately after extraction of the teeth and warrants further investigation.

Guided bone regeneration next to osseointegrated implants in humans.

Abstract: The purpose of this investigation was to evaluate the technique of guided tissue regeneration on a clinical and histologic level for generating new bone adjacent to osseointegrated implants. Cylindrical, press-fitted, titanium plasma flame-coated implants were modified by a disk screwed onto the implant. After implant insertion, the disk-implant assembly was covered by an expanded polytetrafluorethylene membrane. In one group, the space underneath the membrane was filled with hydroxylapatite granules; in the control group, no membrane was used. Clinical and histologic results demonstrate that the principle of guided tissue regeneration is applicable to osteogenesis in humans.

Digital subtraction radiography for the assessment of changes in peri-implant bone density.

Abstract: Digital subtraction radiography is proposed as a potential diagnostic tool for implant research and patient monitoring. Examples of the application of this technique are given observing peri-implant density changes during the early healing phase and during ligature-induced peri-implantitis in an animal model. Additional cases document the loss of peri-implant bone density associated with an infection and increase in density caused by remodeling after functional loading of an implant with a single crown. Digital subtraction radiography might be one of the most sensitive noninvasive methods for assessing subtle density changes in peri-implant tissues, providing additional diagnostic information on implant tissue integration and maintenance.

Histological and clinical comparisons of guided tissue regeneration on dehisced hydroxylapatite-coated and titanium endosseous implant surfaces: a pilot study.

Abstract: Fifty-six endosseous cylindrical implants were placed in dog mandibles 12 weeks after the extraction of all mandibular premolars and first molars. Eight implants, four coated with 50 microns of hydroxylapatite (HA) and four grit-blasted and titanium-surfaced, were placed in each dog. Ideal implant placement sites were modified by creating standardized 3 x 5-mm facial dehiscence defects. Half the dehiscences were treated with a modified expanded polytetrafluoroethylene (PTFE) membrane; the remainder served as controls. After 8 weeks of healing, the animals were sacrificed and measurements made to determine the percentage of dehiscence repair. The HA-coated implants had a mean defect fill of 95.17% and the grit-blasted implants had a percent fill of 82.8% in the guided tissue regeneration (GTR) test group; the control implants demonstrated a mean fill of 55% and 39% in the HA-coated and grit-blasted implants, respectively. Significant differences (P less than .05) were noted between both test groups and the titanium control group, and between the HA test and HA control groups. Histologic evaluation showed significantly greater repair associated with HA-coated implants, as well as significant bone loss associated with clinically exposed membranes. It was concluded that within the limitations of this study, guided tissue regeneration is a viable option in treating defects associated with dental implants.

Histologic evaluation of hydroxylapatite-coated versus uncoated titanium blade implants in delayed and immediately loaded applications.

Abstract: It has been suggested that the long-term success of blade implants could be improved by placing the implants using a two-stage surgical protocol to allow the implant to develop a direct bony interface instead of a fibrous tissue interface This study compared the implant interfaces of delayed and immediately loaded blade implants in nonhuman primates A second objective was to compare the effects of hydroxylapatite coating on delayed and immediate loading applications The delayed loaded uncoated titanium and hydroxylapatite-coated blade implants did osseointegrate This study also suggests that hydroxylapatite-coated blade implants may form a direct bony interface even when they are loaded immediately after implantation, provided that they are splinted to a firm natural tooth

Cobalt-chromium as a framework material in implant-supported fixed prostheses: a preliminary report.

Abstract: Sixty-six consecutive patients treated at the Prosthodontic Clinic in Uppsala, Sweden, received implant-supported fixed prostheses of the Branemark type. The prosthesis frameworks were made of cobalt-chromium alloys. Different techniques for attaching the gold cylinders to the frameworks were used. Mechanical attachment with self-curing polymethyl methacrylate (PMMA), partial soldering combined with PMMA attachment, and soldering only were used. No abnormal tissue reactions were seen. Radiographic examination of the fixtures was performed at the time of prosthesis placement and at the 1- and 3-year follow-ups. A few cases of minor bone loss were detected but not related to the materials used in the superstructures.

Controlled longitudinal study on the psychological effects of osseointegrated dental implants.

Abstract: Forty-seven patients participated in a longitudinal study on the psychological effects of the Branemark implant technique. They were asked to complete questionnaires measuring their psychological well-being and symptom level on two occasions. The first occasion was shortly after the initial prosthetic assessment. Although 29 patients were subsequently accepted for implant treatment, 18 were found to be unsuitable at the later surgical assessment. Both groups of patients were again given the questionnaires approximately 2 years later. The implants were associated with a clinically significant improvement on measures of symptoms and psychological distress, but there was no change in self-esteem. By contrast, the only change in the untreated comparison group was that their level of distress had risen.

Dental implants retrieved from humans: a diagnostic light microscopic review of the findings in seven cases of failure.

Abstract: With the increased use of dental implant systems, an increase in the number of implants removed from patients has also been observed. This investigation attempted to elucidate some underlying causal determinants of implant failure employing light microscopic analyses. Valuable data can be obtained from implants retrieved from patients. Implant success is predicted on proper patient selection and treatment planning, careful surgical procedures, careful prosthodontic management, and continued oral hygiene maintenance.

A new design for a hybrid prosthesis supported by osseointegrated implants: 1. Technical aspects.

Abstract: Maxillary prosthetic restorations on osseointegrated implants are often problematic because of implant location, orientation, and need for lip support. A new design for a hybrid maxillary prosthesis that will provide good esthetics and phonetics, as well as ensure optimum conditions for oral hygiene and patient comfort, is proposed. The design includes separate support, lateral stabilization, and retention. Support is derived from elevated areas at the midline and on the extensions of a bar screwed to dental implants ad modum Branemark. Lateral stabilization is obtained by a removable framework closely fitting the bar. Four precision attachments provide adjustable retention without influencing support. Technical aspects of the procedure are described.

The use and fabrication of a self-retaining surgical guide for controlled implant placement: a technical note.

Abstract: A technique for using a surgical guide construction with a self-retaining feature, which has proven to be a significant improvement for stage 1 surgical procedures, is described. This design is more convenient to use than previously described occlusal extension splints. It maintains the concepts for ideal fixture placement that have proven so valuable in creating both a functionally and esthetically uncompromised prosthesis supported by implants.

SEM evaluation of the in-vitro effects of an air-abrasive system on various implant surfaces.

Abstract: This investigation was conducted to determine the effects of an air-abrasive polishing system on various implant surfaces. Four each of the following types of implants were obtained from the manufacturer: Stryker DB (a titanium alloy implant), Denar Steri-Oss (a pure titanium implant), IMZ (pure titanium polished collar/plasma-sprayed body), and IMZ transmucosal implant extensions (highly polished pure titanium). Four samples of each type of implant material were placed in a group to be treated with an air-abrasive polishing system for 0.5, 1, 5, or 10 seconds, for a total of 16 samples. Scanning electron photomicrographs taken of each sample before and after treatment were analyzed by three examiners who were blind to the treatment conditions. They determined if the abrasion on the treated surface was greater than, equal to, or less than the pretreatment control. No perceptible difference was noted between the pretreatment and posttreatment photomicrographs regarding the surface integrity of the implant material surfaces.

Biomechanical analysis of osseointegration of IMZ implants in goat mandibles and maxillae.

Abstract: This study was designed to determine the effect of time on the biomechanical integration of cylindrical dental implants in the mandible and maxilla. A total of 136 IMZ dental implants was placed bilaterally in the endentulous maxillae and mandibles of 17 goats. Pullout tests were used to assess biomechanical integration at intervals from 2 to 24 weeks. This study indicated that there is a time-dependent, progressive increase in pullout force to 24 weeks. The forces were consistently higher for the mandible than the maxilla. Moreover, there was no correlation between the intraoperative stability of the implant and the postoperative pullout force.

Adaptive changes of masticatory movement characteristics after rehabilitation with osseointegrated fixed prostheses in the edentulous jaw: a 10-year follow-up study.

Abstract: The aim of this study was to assess possible adaptive changes in the masticatory rhythmical pattern after insertion of an osseointegrated fixed denture. Registrations of masticatory cycle duration, mandibular velocity, and displacement were performed before and 2 months and 10 years after rehabilitation. No major changes except for a decreased occlusal level phase had occurred regarding cycle duration over the years. However, a significantly higher mandibular velocity and greater displacement were recorded 2 months after rehabilitation. This trend was further established in the long term. Temporal timing of rhythmical chewing seems to be relatively consistent, suggesting that the central pattern generator driving output over time is constant.

Monitoring of Tübingen endosseous dental implants by glycosaminoglycans analysis of gingival crevicular fluid.

Abstract: Glycosaminoglycans (GAG) in gingival crevicular fluid (GCF) samples were determined by cellulose acetate electrophoresis and densitometric scanning. Two GAG bands, hyaluronic acid and chondroitin-4-sulphate (C4S), were detected in GCF from implants, similar to the profile from teeth. High GCF volumes and GAG contents, notably C4S, may reflect postoperative alveolar bone responses, particularly resorption, at different stages of healing and function of successful implants. They may also indicate adverse tissue changes in failing implants. A comparison of crowned implants and matched teeth suggests that the periodontal ligament contributes to the GCF GAG profile. This may be a useful laboratory method of monitoring implants to detect adverse tissue responses at an early stage.

A new design for a hybrid prosthesis supported by osseointegrated implants: 2. Preliminary clinical aspects.

Abstract: A fixed partial denture is preferred as a prosthetic restoration supported by tissue-integrated oral implants. However, there are occasions, especially in restoring an edentulous maxilla, when a fixed partial denture does not satisfy a patient's requirements for esthetics, good phonetics, proper oral hygiene, and oral comfort. A removable hybrid prosthesis attached to a bar that is conventionally fixed to tissue-integrated implants ad modum Branemark was therefore designed to satisfy such needs and to meet requirements for splinting of the implants. Following the placement of prostheses, patients were asked to give their opinion on the comfort, phonetics, and esthetics of the prosthesis by marking a visual analog scale. The results indicate a successful initial outcome of the treatment.

Microscopic observations of the bone/implant interface of surface-treated titanium implants.

Abstract: Light microscopy, and transmission and scanning electron microscopy were used to evaluate osseointegration of extraoral titanium implant surfaces treated by either autoclaving, exposure to ultraviolet light (UV), or radiofrequency glow discharge (RFGD). Ultraviolet and RFGD-treated implants showed faster healing in the initial 5-week to 3-month period. By 6 months of healing, no structural differences were found at the bone/implant interface among the different treatments. It was concluded that UV or RFGD surface treatment of titanium implants may shorten the time interval between placement and loading.

Tissue integration of Al2O3-ceramic dental implants: an experimental study in monkeys

Abstract: The effect of two different treatment modalities on the tissue integration of Frialit implants was compared in an experimental study in 10 monkeys. The maxillary central incisors were extracted. In one extraction site, chosen by lot, a Frialit implant was immediately inserted, allowing the implant to penetrate the oral mucosa. In the contralateral extraction site, a modified Frialit implant was placed and allowed to heal under a mucoperiosteal flap. None of the implants used in the study was loaded during the observation periods. After experimental periods of 1, 3, 6, and 8 months, the implants were evaluated and monkeys were sacrificed. In situ and histological evaluation showed no significant difference between the two treatment modalities under nonloading conditions. In both cases the healing around the implants was uneventful and good tissue integration was achieved.

Treatment of osseous defects using Vicryl mesh (polyglactin 910) and the Brånemark implant: a case report.

Abstract: The effectiveness of using Vicryl mesh (polyglactin 910) in combination with a Branemark titanium implant is described. A maxillary central incisor with an apical osseous defect resulting from endodontic failure was treated with the Branemark method of osseointegration for single tooth replacement. Vicryl mesh was used over the osseous defect site and uncovered 5 months later. New bone formation filling the defect and around the implant was observed.

An esthetic titanium abutment: report of a technique.

Abstract: New esthetic two-piece titanium abutment cylinders have recently been introduced for the Branemark implant system. The conical design allows for the fabrication of fixed partial dentures with improved esthetics compared to the conventional abutment design. The improved feature provides for the ability to begin the restoration closer to the implant while still maintaining a titanium/soft-tissue interface. Two designs, one short and one long, are currently being produced. The components, techniques, and clinical advantages of the short two-piece esthetic abutment are reviewed.