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A survey of U.S. dentists showed that dental implant use increased 73 percent between 1986 and 1990. More than half of all implants are placed by oral and maxillofacial surgeons. Most dentists who place implants are not affiliated with professional implant organizations; training for implant placement varies widely.
The literature concerning the success rates and the causes of failure of dental implants is reviewed in this paper, and the factors influencing clinical outcome are discussed. Most dental implants seem to be clinically acceptable during the first few years of installation, as long as the initial healing is uncomplicated. On a long-term basis, however, osseointegrated implants are the most reliable among those currently available for routine use. The lack of sufficient scientific data and well-controlled clinical studies with adequate criteria for assessing successful outcome are the main reasons why most other dental implants cannot be clinically recommended without criticism.
The oral rehabilitation by dental implants in patients with diabetes remains a controversial issue. The aim of this study was to evaluate the influence of diabetes mellitus and insulin therapy on the bone healing around dental implants using torque removal. Twenty-seven rabbits were randomly divided into 3 groups with 9 animals each: control (C) group, induced diabetic (D) group, and insulin-treated diabetic (ITD) group (10 U/day). After 1 week, one implant was inserted at the tibial metaphysis of the animals. The glucose levels were periodically evaluated through the glucose-oxidase enzymatic method. The animals were killed at 4, 8, and 12 weeks after surgery and the biomechanical test was performed using a torque manometer. Statistically significant differences regarding the removal torque of the implant could not be found at 4 weeks (P = 0.2) among groups. Group C showed statistically higher values than groups D and ITD at the experimental periods of 8 (P = 0.0001 and P = 0.0002, respectively) and 12 weeks (P = 0.0053 and P = 0.001, respectively). There were no statistical differences between D and ITD groups in any of the experimental periods. Diabetes mellitus has negatively influenced the mechanical retention of implants placed at the tibial metaphysis of rabbits. Therapy with insulin did not induce any changes.
Hydroxyapatite (HA)-coated dental implants have been used clinically for over ten years. Several types of HA-coated implants are available commercially, and a number of clinical and basic studies evaluating the effect of HA coating have been reported. Concerns regarding microbiological susceptibility, resorption, fatigue, and Fracture in long-term application have been pointed out. However, in spite of the aggressive use of HA-coated implants for compromising cases, high success rates have been reported. Our review of the literature suggests that the advantages of using HA-coated dental implants are early bone response and a higher interface shear strength with bone.
OBJECTIVE: To evaluate the integration process of endosseous dental implants by using quantitative bone single photon emission computerized tomography (SPECT). METHODS: Five consecutive patients receiving titanium implants (Astra Tech, Mölndal, Sweden) in the normal edentulous jaw were evaluated by bone SPECT before loading and at regular intervals up to 5 months after loading. Osteoblastic activity at the implant site was compared with activity within the skull (reference) to calculate an osteoblastic activity index (AI). RESULTS: A time activity curve obtained by plotting AI against time over 5 months showed 3 distinct phases of osteoblastic activity: (1) a rise in osteoblastic activity, part of which may reflect postoperative changes, (2) maximum activity about 1 month after implant, and (3) a gradual falloff in the AI, which returned to pre-implant levels at about 4 months. CONCLUSIONS: We conclude that this method offers a simple, reproducible, objective, and physiologic approach to studying the osseous integration process that occurs after endosseous dental implants. In this small series of patients, this osseous integrative process appears to have become established approximately 4 months after loading. This method also has the capability of quantitating bone activity in absolute terms of microCi/gram (microcuries per gram) and can be useful when bone grafting and other surgical procedures are involved.
The Food and Drug Administration (FDA) is reclassifying the manually powered drill bits, screwdrivers, countertorque devices, placement and removal tools, laboratory pieces used for fabrication of dental prosthetics, trial abutments, and other manually powered endosseous dental implant accessories from class III to class I. These devices are intended to aid in the placement or removal of endosseous dental implants and abutments, prepare the site for placement of endosseous dental implants or abutments, aid in the fitting of endosseous dental implants or abutments, aid in the fabrication of dental prosthetics, and be used as an accessory with endosseous dental implants when tissue contact will last less than an hour. FDA is also exempting these devices from premarket notification. This reclassification is on the Secretary of Health and Human Services' own initiative based on new information. This action is being taken under the Federal Food, Drug, and Cosmetic Act (the act), as amended by the Medical Device Amendments of 1976 (the 1976 amendments), the Safe Medical Devices Act of 1990 (the SMDA), and the Food and Drug Administration Modernization Act of 1997 (FDAMA).
The interface between mandibular bone and endosteal dental implants was examined with an in vivo dog model. Undecalcified mandibular implant samples were observed with both conventional transmission electron microscopy and high-voltage transmission electron microscopy (HVEM). Results demonstrated the variable nature of the interfacial support tissues. Mineralized bone was often found within 50 nm of the implant surface, separated from that surface only by an electron dense deposit. Osteocytes were observed close to the interface encased within lacunae extending numerous cellular processes through canaliculi. An osteoblast was also observed directly at the interface within a developing lacuna. Other interfacial areas exhibited a finely fibrillar and more electron lucent morphology. Furthermore, other areas were shown to be composed of wider zones of extracellular products containing collagen fibrils, ground substance, and calcified inclusions. Because bone is an actively growing and remodeling tissue, these different morphological zones around the entire area of the implants would appear to confirm the dynamic tissue response to endosteal dental implants. Further, HVEM stereology was shown to be an exciting research tool to investigate this tissue response.
For years, dental implants have been loaded immediately upon implant placement with varying degrees of success. As clinicians' understanding of the biological and mechanical factors involved in immediate occlusal loading (IOL) has evolved, the success of these procedures has increased--particularly as a treatment option for the restoration of the edentulous mandible or the mandible that will be rendered edentulous during treatment. Due to increasing interest in this treatment alternative, the authors have provided a clear definition of the terminology associated with IOL and have demonstrated the DIEM Guidelines used to increase the success and predictability of such treatment. This presentation also introduces new implant components that simplify the clinical application of the immediate loading concept, enhancing its benefits and acceptance among dental patients and practices alike.
PURPOSE: Cellular fibronectin staining is decreased in adult periodontitis, which implies elastase-mediated degradation of periodontal tissues. The purpose of this study was to determine whether failing dental implants display similar changes. MATERIALS AND METHODS: Cellular fibronectin and its integrin receptors were identified by immunohistochemistry and quantified by computerized image analysis. RESULTS: Cellular fibronectin was found in blood vessel walls, epithelial basement membranes, and fibroblasts. Quantitative results of cellular fibronectin staining were as follows: failing dental implants, median 26.5% (Q3-Q1 = 23%); adult periodontitis, median 5.5% (Q3-Q1 = 5.6%); normal controls, median 12.2% (Q3-Q1 = 7.5%). Cellular fibronectin staining was increased around failing dental implants but decreased in adult periodontitis compared to healthy controls. DISCUSSION: The distribution of integrin receptor subunits alpha4, alpha5, and beta1 of cellular fibronectin was similar in failing dental implants. The pathomechanisms in adult periodontitis and failing dental implants seem to differ. CONCLUSIONS: Adult periodontitis is characterized by proteolysis/loss of cellular fibronectin, whereas failing dental implants are characterized by increased cellular fibronectin deposition, probably as a result of titanium-induced local synthesis and relatively modest degradation.
Nowadays dental implantations are highly successful if individual indications are taken into consideration. From our experiences with patients from the Research Institute for Psychopathology and Psychosomatics, we would like to point out a contraindication for the treatment of dental implants, which until now has been hardly considered. A special case report shows that psychosomatic problems and pains in the maxillofacial region can be the cause of failure of dental implants.
Introducing dental implants into a practice requires planning and commitment. Part of the planning process is learning new clinical skills, but another essential component is developing a marketing approach. The author offers a seven-step plan for adding dental implants to your repertoire.
BACKGROUND: The need for keratinized mucosa (KM) or immobile keratinized mucosa (i.e., attached mucosa [AM]) for the maintenance of osseointegrated endosseous dental implants has been controversial. The purpose of this study was to investigate the significance of KM in the maintenance of root-form dental implants with different surfaces. METHODS: A total of 339 endosseous dental implants in place for at least 3 years in 69 patients were evaluated. The width of KM and AM, modified plaque index (mPI), gingival index (GI), modified bleeding index (mBI), probing depth (PD), and average annual bone loss (ABL) were measured clinically and radiographically by a masked examiner. Based on the amounts of KM or AM, implants were categorized as follows: 1) KM <2 mm (KL); 2) KM > or =2 mm (KU); 3) AM <1 mm (AL); and 4) AM > or =1 mm (AU). Implants were further subdivided into the following four subgroups based on their surface configurations: 1) smooth surface implants (SI) with KM <2 mm (SKL); 2) SI with KM > or =2 mm (SKM); 3) rough surface implants (RI) with KM <2 mm (RKL); or 4) RI with KM > or =2 mm (RKM); or 1) SI with AM <1 mm (SAL); 2) SI with AM > or =1 mm (SAM); 3) RI with AM <1 mm (RAL); or 4) RI with AM > or =1 mm (RAM). The effect of KM or AM on clinical parameters was evaluated by comparing the different KM/AM groups. In addition, the significance of the presence of KM on implant prostheses types (i.e., fixed versus removable) and on implant locations (i.e., anterior versus posterior) was evaluated. RESULTS: Comparison of ABL among the four subgroups in KM or AM failed to reveal statistically significant differences (P >0.05); however, statistically significantly higher GI and mPI were present in SKL or SAL compared to the other three subgroups (P <0.05). GI and mPI were significantly higher in KL (0.94 and 1.51) than KU (0.76 and 1.26) and higher in AL (0.95 and 1.50) than AU (0.70 and 1.19) (P <0.05), respectively. The difference in GI between posterior implants with or without an adequate amount of KM was also significant (P <0.05). CONCLUSIONS: The absence of adequate KM or AM in endosseous dental implants, especially in posterior implants, was associated with higher plaque accumulation and gingival inflammation but not with more ABL, regardless of their surface configurations. Randomized controlled clinical trials are needed to confirm the results obtained in this retrospective clinical study.
LTI pyrolytic carbon blade-type dental implants consisting of a graphite substrate and an LTI pyrolytic carbon coating have a strength that increases with the coating thickness. For implants having a coating thickness of about 0.03 in., average fracture loads of about 1500 lb and 230 lb were obtained in axial compressive loading and eccentric loading (e.g., axial compressive loading plus a bending moment), respectively. Depending on the type of loading, the maximum stresses in the graphite substrate were calculated to be very close to its compressive or tensile fracture strength. Also studied was the effect of a variety of defects on the overall strength of the implants.
BACKGROUND: In 1988, an implant manufacturer offered a new dental implant system, with a wide choice of hollow cylinder (HC) and hollow screw (HS) implants. The purpose of this retrospective study of HS and HC implants was to evaluate clinical and radiographic parameters of peri-implant tissue and to analyze surgical and prosthetic aftercare. METHODS: A total of 89 HS and 26 HC implants in 38 edentulous patients were available for complete evaluation. The patients were treated with overdentures stabilized by two or four implants. The follow-up period was 10 years. RESULTS: The results of the clinical evaluation showed a mean sulcus probing depth of 3.3+/-1.3 mm (range=2 to 10 mm). The mean radiographic bone loss was 2.2+/-2.1 mm (range=0.1 to 12.2 mm). One implant (HS) was removed during the osseointegration period. Three other implants (two HS and one HC) in three patients had to be removed after 10 years. The survival rate of the HS implant (96.6%) was comparable to the HC implant (96.1%). The success rate of the HS implant (93.3%) was slightly more favorable compared to the HC implant (88.5%). The HS and HC implants met the Albrektsson criteria of success. CONCLUSIONS: HS and HC implants provide a stable base for long-term support of a mandibular overdenture. Furthermore, it is important to monitor peri-implant bone level by taking annual radiographs and measuring probing depth, especially after prolonged service.
The prospective study of dental implant application into the reconstructed maxilla alveolus of cleft patients was started in 2001. Its aims are to specify precisely the indications, conditions and techniques, as well as the factors justifying the assumption that the results will be successful. Indication was based on an examination by a multidisciplinary therapeutic team (plastic surgeon, dental surgeon, orthodontist, and prosthetist), with the proviso that the patient should have a positive approach. Successful orthodontic treatment of intergnathic relation and shape of the dental arches served as the basis. It was followed by a reconstruction of the defective alveolus using autologous cancellous bone grafts, harvested from an iliac crest. Dental implants were inserted 12-15 weeks after the transplantation and subsequently a prosthetic component was applied with a time delay of at least 2 months. After the orthodontic preparation, reconstruction of the alveolus has so far been performed in 38 patients. Their age was at least 14 years, i.e. the age when growth of the orofacial region was finalised or already complete. The crucial tasks at this stage are to form a stable, three-dimensional voluminous alveolar crest, and to cover the grafts with a sufficient amount of quality soft tissue. We needed an average amount of 3.7 ccm of cancellous bone graft for the reconstruction. This amount can be harvested only from an enchondral bone. For soft tissue shell the mucoperiosteal shift of flap from cleft segment was used. In more serious cases contralateral or even bilateral shift was performed. The relief of tissue tension was performed by double cut-back. Using the approach described we attained a 84.2% success rate. Our results and experience derived within this project show that the success rate of this procedure depends on the continuous flow of the alveolar arch with a good intergnathic relation, with a length of defect between crowns of border teeth of at least 8 mm. The original osseous walls of the defect must definitely be of suitable height. On-lay augmentation does not work in these cases. A subsequent pitfall lies in resorption of transplanted bone, which may be reduced due to an early load by a dental implant. During the three months after the reconstruction a spongy osseous graft matures enough to ensure the primary stability of a fixture. We emphasise the necessity of close co-operation of the therapeutic team in such cases.
OBJECTIVE: To investigate the influences of bicortical anchorage on values of natural frequencies of dental implants utilizing the 3-dimensional finite element analysis. METHODS: Using the commercial code of Solidworks, 3-D models of a screw-shaped dental implant and a mandibular bone segment were generated. After the 3-D implant-bone complex was meshed by ABAQUS software, effects of bicortical anchorage on the buccolingual and axial first-order natural frequencies of the implant were computed. RESULTS: Bicortical anchorage increased both the buccolingual and axial natural frequencies remarkably. As the bicortical anchorage got deeper, the frequencies correspondingly got higher. CONCLUSION: Bicortical anchorage can increase the buccolingual and axial primary stability of dental implants.
Cigarette smoking is known to adversely affect wound healing, and thus may jeopardize the success of dental implantation and implant-related oral surgery. The present study is aimed to present the influence of cigarette smoking on the success and survival of dental implantation as well as on the complication and success of implant-related surgery. We conclude that smokers undergoing both implant-related surgical procedures and dental implantation should be encouraged by their dentists, oral and maxillofacial surgeons, or treating physicians to cease smoking, emphasizing that smoking can increase complications and reduce the success rate of these procedures.
PURPOSE: To evaluate long-term clinical performance of 1-stage dental implant prostheses at a single clinic, emphasizing clinical and demographic characteristics that affect implant survival. MATERIALS AND METHODS: Dental records of all 308 patients (674 implants) treated with 1-stage implants at Mayo Clinic from October 1993 through May 2000 were reviewed from implant placement to last visit. Exposure and outcome variables affecting performance were collected separately to control bias in the data collection process. Additional confounding factors (age and sex) were adjusted with the stratified Cox proportional hazards model. Implant survival was determined by means of a Kaplan-Meier survival estimate. The log-rank test was used to determine the role of clinical and demographic variables in implant survival. The relative risk associated with the possible effect of clinical and demographic variables on implant survival was estimated with the Cox proportional hazards model. RESULTS: The implant survival rate (n = 654 implants) was 97% (mean +/- SD follow-up, 21.0 +/- 18.8 months; range, 1 to 78 months). Performance bias was limited because nearly all patients were treated by 1 prosthodontist. Two implants failed after loading (6 and 9 months). The incidence of complications was less than 4%. Among the implant failures, use of heterogeneous bone graft was associated with 4.8 times more failures than was use of autogenous bone graft (P = .04). After augmentation, delaying implant placement for 5 to 6 months resulted in 8.6 times more failures than the rate after earlier placement (P < .001). DISCUSSION: Retrospective review of the clinical performance of a 1-stage dental implant system yielded a 97% survival rate, with no failures noted after 13 months. Prosthetic complications were low, especially for fixed implant prostheses. CONCLUSION: Clinical performance of 1-stage dental implant prostheses between 1993 and 2000 demonstrated a high level of predictability.