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Failure of osseointegration and mechanical accidents are the most common complications of dental implants. The functional prognosis is preserved in any case. Most of these complications can be avoided by a careful patient selection, a strict surgical phase and restorative procedures realized by competent practitioners.
A study was undertaken to evaluate the ion-beam texturing of aluminum oxide as a means of providing a surface which will produce a biological prosthetic attachment. A wafflelike pattern of surface contours 150 x 75 x 35 microm deep was produced on cylindrical dental implants. The textured surfaces were compared to the as received surfaces in adult mongrel dogs. Implants were inserted into surgically modified healed extraction sites and were left in place for six months. Post-sacrifice mechanical testing was used to quantify the displacement response of the implants. The clinical, radiographic and mechanical testing evaluations did not reveal any statistically significant differences in the performance of the dental implants. However, it was observed that anatomical site and mandibular geometry with respect to implant size play a significant role in affecting implant retention.
The purpose of this paper is to present the results of the evaluation of five patients who received titanium dental implant replicas of extracted molars and pre-molars, placed in the posterior mandible. The replicas were placed in the sockets where the molars and bicuspids had been extracted. The implant replicas were fabricated in two parts, an abutment portion and a root portion connected by a titanium screw. The root portion was made of cast titanium. The abutment portion was made of a high noble metal to which porcelain could be fused, so that the crown restoration could be made directly on the abutment. The patient's ages ranged from 27 to 63 years. Four were male and one was female. The implants were placed three to six weeks after extraction. All implants integrated. The longest follow-up with the implant in function was five years.
The mechanical stability of the fixture in bone is one of the most important factors for the long-term reliability of dental implants. This paper focuses on an experimental procedure to evaluate the mechanical properties of the bone surrounding dental implants. The procedure is based on a surgical animal model followed by mechanical tests. The experimental mechanical testing has been used for preliminary investigations on the role played by different parameters such as the healing time and the surgical technique (standard or with regenerative material). The procedure has been evaluated in some preliminary tests on a few specimens. Microradiographic analyses have been performed on the bone surrounding the implants in order to give an interpretation of the bone properties on the basis of the bone morphology and to distinguish the newly formed bone from the pre-existing bone. The preliminary results relevant to 10 threaded titanium implants are presented and discussed. Our findings show that the mechanical properties of the bone surrounding the implant improve with the increase in the healing time from 24 to 45 days. The ultimate loads recorded during mechanical tests arise from 395 N to 2665 N in case of coronal defects filled with bone regenerative and from 2200 N to 5700 N in case of standard technique.
Two patients were referred to the Graduate Periodontal Clinic, one for placement of dental implants, the other for treatment of advanced periodontal disease. It was determined from an analysis of the Hounsfield scales of bone density from a CT scan that the patient requesting dental implants had severe osteoporotic changes and was, therefore, not a good candidate for the procedure. The second patient's medical history revealed multiple fractures occurring over the years that suggested the presence of osteoporosis. This diagnosis was subsequently confirmed by referral of the patient to an osteoporosis clinic.
To study the influences of a modified sandblasted surface (developed by the authors) on the integrating status of titanium (Ti) dental implants and bone in vitro, a three-dimensional experimental model of implant material-osteoblast culture was used. The interaction of Ti discs and osteoblasts at the interface was followed with phase-contrast microscope examination and was further observed histologically and ultra-structurally after one-month culture. Results showed that there was no significant difference between the modified sandblasted surface group and the smooth surface group in the capacity of osteoblasts migrating and attaching to Ti discs. There was, however, a significant difference in the pattern of attachment. Around the polished surface, the migrating and attaching osteoblasts oriented themselves parallel to it; however, around the modified sandblasted surface, the osteoblasts were migrating and attaching perpendicularly. There was also a major difference in the shapes of cells lining the interface; spindle-shaped on the smooth surface versus round and ovoid with a large cellular body and abundant cytoplasm on the modified sandblasted surface. Moreover, transmission electron microscopy revealed an active secretion of collagen fibrils, a bone-matrix-vesicles-mediated mineralization process, and the formation of osteocytes in the modified sandblasted surface group. Therefore, at this in vitro level, it can be concluded that the modified sandblasting surface treatment of dental implants can facilitate bone healing at their osseous interface and enable the real perpendicularly connecting bone-fiber osseointegration to form instead of the capsule-like osseous adaptation.
The aim of this paper was to identify factors significant to the use of single-stage dental implants in the aesthetic zone and discuss treatment considerations related to them. In view of available literature and clinical experiences, treatment outcomes associated with the use of single-stage Straumann implants (Institut Straumann AG, Waldenburg, Switzerland) in the aesethetic zone can be considered positive and predictable.
A statistical analysis was carried out on the clinical evaluatory data gathered from a two-year longitudinal study of the single-crystal sapphire endosteal dental implant in dog jaws. Statistically, the implants behaved either better than control molars (clinically), or in a manner similar to control molars. These data suggest an excellent prognosis for the single-crystal sapphire dental implant.
PURPOSE: Vascularized iliac bone graft combined implantation has become a routine procedure in the functional reconstruction of mandibular defects. The aim of this study was to assess the clinical outcomes of the implants immediately placed into the vascularized iliac bone grafts. METHODS: In this study, 12 consecutive patients with 36 ITI dental implants who had reconstruction of mandibular defect between 2000 and 2004 were presented. All implants were inserted immediately after bone grafting and loaded after 3 to 5 months of submerged healing. RESULTS: In general, a primary stability for implants placed in vascularized iliac bone grafts were achieved. After 1 year of observation the mean vertical bone loss was less than 1mm. There was no implant failure in the observation period. CONCLUSION: The vascularized iliac bone grafts are safe implant-bearing areas and allows a reliable and predictable restoration with dental implants. Implant-supported bridges and overdentures can be used in this procedure.
The mechanical properties of porous polysulfone (PSF) were determined and its performance as a surface coating on orthopedic and dental implants evaluated. Ten coated femoral prostheses were implanted in nine dogs. A second series of four uncoated "control" prostheses and all of the acetabular cups were implanted using conventional bone cement techniques. Six porous PSF coated tooth roots were implanted in healed mandibular premolar extraction sites in three Rhesus monkeys. The shear strength of porous PSF (6 MPa) was comparable to that of trabecular bone. Pushout tests of 1cm. thick sections of the prostheses yielded interfacial shear strength values over 1.4 MPa for the PSF coated hips after 14 weeks and mean values under 0.7 MPa for the bone cemented specimens after 3 and 36 weeks. Bone and fibrous tissue was identified in the pores of coated specimens. Preliminary clinical evaluation of the functioning dental implants revealed zero mobility and other favorable clinical and radiographic indications after 2 months.
The clinical replacement of lost natural teeth by osseointegrated implants has represented one of the most significant advances in restorative dentistry. Two decades ago, a majority of dentists were sceptical about implants and rejected them entirely. Today it is rare to find a practitioner who does not work with dental implants or who is not actively participating in one of the many seminars or courses offered by universities, professional societies and implant manufacturers.
INTRODUCTION: Recent developments in computer assisted surgery have brought major improvements to maxillofacial surgery. Computer systems for intra-operative navigation have been introduced enabling the surgeon to locate the continually updated position of the instruments and the operation site on the patient's three-dimensional reconstructed image data set displayed on a monitor in the operating room. Complex surgical procedures can be performed according to the preoperative plan based on CT and/or MRI data minimizing surgical risks and optimizing clinical results. Nowadays computer-assisted-surgery has also proved effective in dental implantology. AIM: The objective of this study was to compare the accuracy of conventional and computer-assisted dental implantation planning and surgery. Analyzing our early experiences, we aimed to evaluate the benefit from utilising computer assisted surgery (CAS). PATIENTS: Five patients were treated with the aid of CAS, a total of 18 dental implants being placed. Only difficult operation sites, e.g. following bone augmentation or anatomically malformed jaws were included in this study. METHOD: An infra-red light based navigation system (Vector Vision 2, BrainLAB, Munich, Germany) including a three-dimensional planning approach for maxillofacial surgery was used. Placement of dental implants in the maxilla included direct visualization when drilling the implant socket according to the axis previously planned on radiographs and CT scans. RESULTS: In two cases the conventionally planned implant location had to be changed due to insufficient bone being available. With four implants, it proved possible to insert longer fixtures after the CAS system had evaluated all parameters of the surgical region. In one case a shorter implant was installed due to insufficient bone at the designated location. CONCLUSION: The use of an image-guided navigation system provides a valuable tool in implant dentistry and proved superior to conventional implant surgery especially in difficult anatomical regions.
We have been using dense, pure hydroxyapatite (HA) dental implants for the last 15 years and results have shown that dense HA is a chemically stable material with acceptable mechanical properties. However, due to HA's physical characteristics, particularly its brittleness, there is the risk that the implant will fail if the subsequent bone binding comprises less than one half of the root portion. To ensure greater implant success, a new cementing method has been developed that uses methacrylates for the bonding of the dense HA outer shell to the titanium (Ti) inner cylinder in a two-piece HA-cemented Ti implant. Mechanical property tests were conducted to compare the HA-cemented Ti implant bonded with this new acrylic cement with existing commercially available HA-cemented Ti implants bonded with a triethyleneglycol dimethacrylate (TEGDMA)-bisphenol-A diglycidyl ether (BisGMA compound). The vertical and horizontal compressive strength of this improved implant was respectively 3.4 and 6.1 times greater than the commercial implants. This increased strength of new acrylic cement is due to its ability to compensate for shrinkage that affects adhesion during curing, thereby providing stronger bonding.
Two types of isoelastic endosseous dental implants were produced and their functionality was tested. One type consisted of a porous sintered TiTa30 alloy, the other had a special surface structure consisting of titanium wire loops. Their mechanical properties were optimized by the production parameter (sintering and diffusion bonding, respectively). The functionality was tested after insertion into an artificial jaw which had properties corresponding to the natural mandibular. The elastic properties of both implants were similar to the properties of the bone. In addition the implants have a safe anchorage bone ingrowth. In animal experiments using the implant with surface loops it was observed that the bone entered the loops and even extremely small surface cavities in the wire loops.
A prospective study for the treatment of mandibular edentulism using the new Astra dental implant system was conducted on 54 patients. The clinical performance of 310 implants was monitored over 3 years. The survival rate was 100% for the prostheses and 98.1% for individual implants. Four implants failed during the first 3 months after placement, one was retained as a "sleeper," and two more were removed because of persistent discomfort. Both resorption and deposition of mandibular marginal bone were observed. Bone changes from baseline to the end of the first year ranged from -0.4 to +1.0 mm (median 0.00), from the first to the third year from -0.8 to +0.6 mm (median 0.04), and over the 3 years ranged from -1.1 to +1.0 mm (median 0.01). No marked mean bone resorption was observed during the first year compared to the two following years. A significant gain in marginal bone level was recorded in males, but in females the level was unchanged. There were no serious inflammatory reactions in the surrounding soft tissues during the 3-year follow-up period.
BACKGROUND: Successful endosseous implant placement requires that the implant be stable in alveolar bone. In certain cases, the implant can be stabilized in native bone but some part of the implant is not covered by bone tissue. This often occurs during placement of implants into extraction sites or in areas where bone resorption has occurred and the ridge width is not sufficient to completely surround the implant. In those cases, the clinician usually employs a procedure to encourage bone formation. These procedures typically include a bone graft and/or membrane therapy. Recent advances have led to the isolation, cloning, and production of recombinant human proteins that stimulate bone formation. One of these bone morphogenetic proteins (rhBMP-2) has been extensively studied in animal models and is currently being tested in human clinical trials. METHODS: In this study, rhBMP-2 was tested using a collagen sponge carrier to stimulate bone formation in defects in the canine mandible around endosseous dental implants. Six animals had a total of 48 implants placed. rhBMP-2 with the collagen carrier was implanted around 24 of these, the remainder having only the collagen carrier placed. Half the sites were covered with a nonresorbable expanded polytetrafluoroethylene membrane. Histologic analysis was performed after 4 and 12 weeks. The area of new bone formed, percentage of bone-to-implant contact in the defect area, and percentage fill of the defect was calculated. RESULTS: The addition of rhBMP-2 resulted in significantly greater amounts of new bone area and percentage of bone-to-implant contact and with more percentage fill after 4 and 12 weeks of healing. The area of new bone formed was reduced after 4 weeks when a membrane was present but after 12 weeks, there was no significant difference between membrane and non-membrane treated sites. In some specimens, new bone was found coronal to the membranes, with rhBMP-2-treated sites having greater amounts than non-rhBMP-2-treated sites. CONCLUSIONS: These data demonstrate that a bone differentiation factor significantly stimulates bone formation in peri-implant bone defects in the canine mandible. In addition, bone-to-implant contact was significantly enhanced along the rough implant surface. Membrane-treated sites had less new bone formation after 4 weeks of healing but were similar to non-membrane sites after 12 weeks. These results demonstrate that rhBMP-2 can be used to stimulate bone growth both around and onto the surface of endosseous dental implants placed in sites with extended peri-implant osseous defects.
INTRODUCTION: Prosthetic rehabilitation, particularly in radiated areas, can be particularly difficult in patients with partial or total edentation following treatment for orofacial cancer. We report a series of patients who underwent a protocol of implantation in radiated bone with evaluation of the prosthetic rehabilitation. MATERIAL AND METHOD: Thirty-three patients given radiotherapy for an orofacial cancer were implanted, followed by a dental prosthesis. The three phases of the protocol were a preoperative clinical and radiological analysis, a surgical phase under general anaesthesia and a postoperative clinical and radiological follow-up. RESULTS: Fifteen patients were treated for an oral cavity tumor, ten for a pharyngeal lesion, six for a laryngeal tumor and two for a maxillary cancer. The average dose of radiotherapy was 60.5 Gy. Sixty-eight implants were positioned, 91.9% in the anterior mandible. The delay between radiotherapy and implantation was 54 months. The delay between implantation and loading was seven months. The average follow-up was 31.9 months. No peri-implantitis was observed. DISCUSSION: Implantation in irradiated bone is possible if a strict protocol is used; a good rate of success and improved quality of life will favour development of this technique. Criteria for dental implant placement include local and general conditions, the psychological situation and technical possibilities. Sufficient delay after radiotherapy is necessary to verify healing and the good prognosis of the cancer. The vascular supply can be preserved by implantation under general anesthesia. All patients were satisfied with the functional and esthetic results.
This investigation was performed to assess the bone-to-implant surface contact at fixtures of titanium that either had a standard machine prepared or a TiO2-blasted surface. Five beagle dogs were used in the experiment. Extractions of the premolars were performed in the maxilla. After 4 months of healing, 5 standard machine-prepared fixtures and 5 prepared according to the TioBlast technique were inserted. Two months later another 5 "standard" and 5 TioBlast-prepared implants were inserted. Four months after the first fixture installation, the animals were killed and ground sections prepared from each implant site. Of the 20 implants installed, 19 were successfully incorporated. The mean bone-to-implant surface for "standard" fixtures was about 40% both at the 2 and 4 months observation interval. The corresponding figures for the TioBlast-prepared fixtures were similar during the first 2 months of observation, while subsequently the TioBlast-prepared fixture surface seemed to stimulate to a more close bone-to-implant contact (65%) than the "standard" one.