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Osseointegrated implants as anchors for various prosthetic reconstructions have become a predictable treatment alternative. It was expected that implants required submucosal placement during the healing period for successful tissue integration. However, it has been demonstrated that healing and long-term health of implants could be achieved with equal predictability in a 1-stage, non-submerged approach. This prospective 5-year study not only calculates implant success by life table analysis, but also evaluates the correlation between observed bone level changes with clinical parameters as measured by suppuration, plaque indices, bleeding indices, probing depth, attachment level and mobility. A total of 112 ITI dental implants were inserted in different areas of the jaws. Clinical and radiographic parameters were evaluated annually for 5 years, whereas a portion of the study group for which 6-year evaluations were available were included in the life-table analysis. The overall success rate after 5 years in service was 99.1%, while after 6 years it was reduced to 95.5% due to the fracture of 3 implants in 1 patient. The mean crestal bone loss experienced during the first year was 0.6 mm followed by an annual yearly loss of approximately 0.05 mm. No significant differences could be found between the amount of bone loss measured at each of the yearly follow-up visits. This suggests that statistically the followed implants did not show any radiographically measurable bone loss following the initial period of bone loss associated with implant placement and osseointegration. Low levels of correlation between the individual and cumulative clinical parameters with radiographically measured bone loss suggests that these parameters are of limited clinical value in assessing and predicting future peri-implant bone loss.
Dental students at Tokyo Medical and Dental University are taught to prepare teeth for full cast crowns with a wall taper of 2 to 5 degrees and an occlusal clearance of 1.2 to 1.5 mm. However, it is difficult to achieve such an ideal taper. The objective of this study was to examine the abutment taper and height of teeth prepared for crowns by final-year dental students under clinical supervision. To evaluate the degree of taper and height of the prepared teeth, shadowgraphs of 63 working stone dies were traced. The angles and height of the abutments were then measured on the same tracing. Only 12.7% (8 out of 63 abutments) of the prepared teeth fell within the ideal range of 2 to 5 degrees, and the average taper was 9.5 degrees (19.0 degrees convergence angle). The average abutment height varied from 4.8 mm to 6.9 mm and showed a close relationship with the abutment taper. The average taper, 9.5 degrees, of the present study was larger than the ideal taper; however, it was thought to be clinically acceptable as it is difficult to achieve the ideal taper intraorally.
PURPOSE: This long-term follow-up study aimed to compare the outcome of fixed prostheses supported by teeth and implants and by freestanding implants only. MATERIALS AND METHODS: From prosthesis insertion up to 14 years (mean 6.5 y), 18 patients were followed. Implant-supported prostheses with and without tooth connection were compared within the same jaw. The tooth-implant prostheses were supported by 30 implants and 30 teeth, and the freestanding prostheses were supported by 48 implants. Implant outcome, marginal bone stability, and mechanical complications were recorded. RESULTS: Neither implant mobility nor fractures of any component of the implants were observed. No prosthesis complications were observed, and the same applied for crown cement failure and intrusion of teeth. Only one periapical lesion was detected at the first follow up. The annual change of the marginal bone level around connected and freestanding implants did not differ significantly. The mean marginal bone loss (over the 2 groups) for the first 6 months amounted to 1.08 mm. After the first 6 months, an annual marginal bone loss of 0.015 mm was observed. There was no difference between the 3 connection types (single implant connected to single tooth, multiple implants and/or multiple teeth connected with single connector, and multiple connectors) for the first 6 months or thereafter. The marginal bone loss (over the 3 groups) for the first 6 months was 1.15 mm. After the first 6 months, the annual bone loss (over the 3 groups) amounted to 0.015 mm. CONCLUSION: Based on the results of this study, splinting teeth with implants for implant-supported fixed prostheses did not affect the long-term outcome in comparison to freestanding implants.
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Collagen degradation products of the carboxyterminal region possibly reflect bone and attachment loss. In the present study, the Serum CrossLaps One-Step enzyme-linked immunosorbent assay was used to determine a specific part of the carboxyterminal region of type I collagen, the CrossLaps. Samples of peri-implant and gingival crevicular fluid of 111 implants and 53 teeth from 47 partially or completely edentulous patients were examined in reference to levels of CrossLaps and beta-glucuronidase (beta G), an established marker of periodontal disease. Clinical probing pocket depth (PPD), bleeding on probing (BOP), plaque accumulation, mobility, radiographic bone loss, and the occurrence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia were assessed. The mean values were: for PPD at implants 3.76 +/- 1.41 mm, at teeth 3.44 +/- 0.88 mm; for beta G at implants 0.364 +/- 0.392 pU/min, at teeth 0.314 +/- 0.209 pU/min; for CrossLaps at implants 0.069 +/- 0.059 pmol/min, at teeth 0.082 +/- 0.053 pmol/min. Bleeding on probing was significantly higher on implants than on teeth (McNemar test, P = .004). No significant difference of beta G levels was found between teeth and implants (Wilcoxon test). A negative correlation was found between beta G levels and CrossLaps levels at teeth (Pearson-rank correlation, P = .002). On implants, no significant correlation of these 2 parameters was seen, but significant correlations were found between sulcus fluid flow rate and PPD (P = .012), beta G levels and bone loss (P < 0.0005), and CrossLaps levels and PPD (P = .011). CrossLaps can be detected in both gingival and peri-implant crevicular fluid. While rising levels of beta G may indicate acute peri-implantitis, CrossLaps may not, but could play a role as a marker of ongoing attachment loss.
In a private practice, 299 patients were treated with 1010 full-ceramic restorations within a period of 39 months. The inlays and onlays were manufactured using the Cerec technique, and were seated in one single appointment. The clinical success was observed and documented continuously. Re-examination was conducted 9 to 12 years after the placement. According to the Kaplan-Meier method, the probability of survival decreased to 90% (s = 0.018) after 10 years and 84.9% after 11.8 years with no further loss by the final observation at 12 years. Size and outline form did not affect the success rate. Premolars rated better than molars. Vital teeth provided better results than non-vital teeth. The application of dentin adhesive increased the probability of success. Eighty-one failures were recorded during the observation period. The most frequent reason for failures were fractures of ceramic and tooth.
The present article describes the preliminary results of a short-term follow up retrospective study of 104 external hex, screw-type MIS implants with rough surface that were consecutively implanted in 34 patients. The implants were followed up between 1 to 3 years. 49 implants were placed in the maxilla and 55 in the mandible. Bone regenerative procedures were carried out simultaneously in the time of implant placement in 21 of the implants. A total of 6 implants failed (5.7%) during the observation period, all in the first year after implant placement. Two implants failed in the same diabetic patient, and one in a heavy smoker. Two of the failed implants were placed together with bone regenerative procedures, and another one was with no initial stability at the time of implant placement. This short-term follow up report has shown that the success rate of MIS screw-type implants with rough surface is similar to the success rate reported for other implant systems. However, long-term follow up is needed to verify the long-term success MIS implant system.
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The use of implants to replace missing single teeth has become a valuable treatment option. This study presents a 5-year retrospective clinical analysis of single teeth replaced with hydroxyapatite-coated implants. Of the 271 cylinder and screw implants placed over this period, 12 were lost (survival rate = 95.57%). In addition to aesthetic compromise, the most frequent complication was loosening of the abutment screw. These results corroborate findings from the literature and suggest that the described procedure can be safely performed in daily restorative procedures.
A series of 12 men and 13 women ranging in age from 24 to 71 years underwent two- or three-dimensional reconstruction of type C, D, or E ridges and placement of anterior implants. The mean horizontal augmentation was 6.4 mm (range 2 to 17 mm), and the mean vertical augmentation was 4.22 mm (range 0 to 15 mm). The 67 implants were all loaded, with the time averaging 34.4 months for the maxillary implants and 19 months for the mandibular implants. None of the implants have been lost to date. Two patients had flap retraction within the first 2 weeks that necessitated reapproximation. One patient had total failure of a J graft of iliac crestal bone from the maxillary left central incisor to canine starting 3 weeks after placement as the result of infection. The graft was removed at 6 weeks, and no implants were placed. Two patients suffered partial anterior graft loss, but their implants were successful in location and angulation. Implants and grafts can be combined with acceptable rates of complications and failure.
Implant exposure during initial healing after placement has been considered important in both implant integration and postloading effects. This study evaluated the effect of early implant exposure on the clinical findings prerestoration and 6 months postrestoration. Forty-eight implants (24 CPTi and 24 Ti-13-13) were placed in maxillary and mandibular posterior sites in six baboons. Implant exposure was evaluated for 24 of the submerged implants at placement and at each weekly visit for 3 weeks after implant placement. The crestal bone level at maxillary posterior sites was measured at 6-month uncovering, and mandibular sites were measured at 3-month uncovering. All sites were again measured 6 months after restoration placement. Periotest readings were recorded at implant uncovering and again 6 months postloading. Arbitrary groupings of the Periotest values were assigned as good = -7 to -1; guarded = 0 to +2; and poor = +3 to +27. At 6 months postloading, there were no statistical differences between CPTi and Ti-13-13 for change in crestal bone height in either arch. The mean change in maxillary crestal bone height varied from a 0.59- to 1.35-mm loss. The differences between the mean exposed and nonexposed changes were not statistically significant The mean change in mandibular crestal bone height varied from a 0.25- to 0.88-mm loss. Changes in crestal bone height for nonexposed sites from 3-month implant uncovering to 6 months postloading were statistically significant at the mesial, buccal, and lingual aspects. The mean change for the nonexposed distal aspect approached significance. The differences between the mean exposed and nonexposed changes were not statistically significant. The overall percentage of maxillary implants in the good category for nonexposed sites decreased by 41% from uncovering to 6 months after loading, while no change occurred for exposed sites; the percentage of implants in the good category was comparable for early exposed and nonexposed sites (57% and 59%, respectively). At 6 months after loading, the percentage of implants in the good category was more favorable for early exposed (88%) than nonexposed sites (50%). A one-stage implant approach should provide similar postloading clinical results as the two-stage surgical approach.
Electron microscopic study of the structure of zinc-phosphate cement fixing artificial crowns detected its porous structure: isolated cavities and connected 0.3-10 mcm microspaces. These formations in the cement structure are stable and do not depend on the duration of permanent fixation of dentures. The authors claim that porous structure of materials used for permanent denture fixation is their important characteristic. The role of microspaces in fixing cement in the penetration of saliva under the artificial crown and the probable effect of this factor on caries development under the crown is discussed.
A single implant-supported restoration is one treatment alternative to consider for the replacement of a missing tooth. Technological advances in materials and machining have led to the development of a densely sintered aluminum oxide ceramic abutment, designed and machined using CAD/CAM technology. This manufacturing method improves management of the subgingival depth of the crown/abutment interface and enhances the esthetic qualities of the restoration. However, since this ceramic abutment has less mechanical resistance than metal abutments, its use should be confined to the restoration of incisors and premolars not subjected to excessive occlusal forces.
The single-tooth restoration has become one of the most widely used procedures in implant dentistry. Improvements to the abutment implant interface design, wider implant platforms and the increased use of cemented restorations have greatly enhanced this procedure. Nonetheless, limitations in the volume of underlying bone and heavy occlusal loads, with or without parafunctional habits, still contribute to occasional disappointments in restoration stability. The use of 2 implants to restore a molar has been shown to eliminate problems associated with bone volume and prosthetic stability. One of the most significant barriers to the widespread use of this concept has been the limitation of the size of implants and their associated prosthetic components. This paper presents the use of 2 implants to replace a single molar using implants and prosthetic components in the Astra Tech Dental Implant System.
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The early loss of the anterior primary teeth can cause problems in phonation, development of the maxilla and is related to deleterious habits. This case presents the clinical sequence of rehabilitation of upper anterior primary teeth, where endodontic treatments were done. This was followed by the construction of root post using polyethylene ribbon fibers and the fabrication of crowns composed of resin.
OBJECTIVE: The present study was to explore the corrosion resistance of three kinds of magnetic retainers which named neodymium-iron-boron magnet and encapsulated in stainless steel. METHODS: Three kinds of magnetic retainers were exposed for 6 months to artificial saliva thermostated at 36.5 degrees C. This study included a electrochemical test as polarization curves and a chemical test as immersion test. RESULTS: In the electrochemical test, current density of the national keeper was 7.015 microA/cm2 and magnet was 0.119 microA/cm2. In the chemical test, corrosion rate of national keeper was 3.67 x 10(-5) mg/cm2.h and magnet was 1.77 x 10(-5) mg/cm2.h. The corrosion resistance of the national magnetic retainer had little difference with the imported ones. CONCLUSION: Transient exposure of stainless steel to artificial saliva environment is likely to significantly increase elemental release. It would affect the useful life span of magnets.