Cemented versus screw-retained implant prostheses: which is better?
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Cementation↗
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Clinical evaluation of two-piece apatite dental implants in 189 cases.
A two-piece apatite implant composed of a titanium abutment and a titanium tubular root portion cemented to an outer dense hydroxyapatite (D-HAP) tubular shell by resin cement has been authorized as High Advanced Medical Technology (H.M.A.T.) and applied since December 1987. We will show the success rate and the evaluation of the implants applied through May 1992. A successful implant was considered as one that provides functional comfort with no mobility and the absence of surrounding mucosal inflammation. The number of implants applied during the last 4.5 years was 810 pieces in 189 cases with an overall success rate of 92.5% for the 704 implants with abutment. The extirpation rate has no clear linear association with the duration of the implant or with the patient's age. Most of the extirpations resulted from cases where the patient used a provisional denture during the bone healing period, the time between implantation and abutment cementation. Extirpation rate of implant was high in cases using large maxillary provisional dentures with ten or more missing teeth. It is believed that all implant cases in which large dentures were used frequently contributed to the extirpation. These observations led us to suggest that provisional dentures may be harmful to the implant. When we shifted from the traditional method to the Delay Method 2.5 years ago, no incidence of extirpation was experienced in the mandible, even with the use of provisional dentures. In the maxilla, the Delay Method proved to be effective without the provisional denture. However, the results of the Delay Method with provisional dentures remains to be evaluated. The reason is that too few cases were encountered with large missing teeth to suffice for our observation. This Delay Method (named by us) consists of delaying the insertion of the implant for approximately 2 months after the first socket preparation, until the bone tissue activity has risen. After some adjustment in the prepared socket, the implant is then inserted during the second surgical procedure. We therefore consider this method of potential benefit over the traditional method.
Aged↗
Various designs of ceramometal crown for implant restorations.
The posterior design of the implant superstructure (the ceramometal crown) was classified into four categories: a ceramometal crown with an access hole on top; a cemented ceramometal crown; a ceramometal crown retained with a lingual screw; and a telescopic ceramometal crown. Cemented ceramometal crowns and telescopic ceramometal crowns are considered simpler, more esthetic, and more resistant to fracture among the four models.
Bicuspid↗
[The use of the Periotest method for the clinical assessment of the efficacy of dental implantation].
The paper describes a modern diagnostic method: Periotest for assessing the stability of intraosseous implants. The mobility of implants after remote and immediate implantation is assessed in 65 patients with dentition defects. The study yielded complete information on the status of tissue complex, detected the early signs of impaired bone integration after implantation, and helped more reliably predict the results.
Dental Implantation, Endosseous↗
[The restoration of premolars and molars with titanium pin inserts with composite coatings].
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Adult↗
Numerical analysis of a dental implant system preloaded with a washer.
Gold screw loosening is a problem that frequently affects dental implants. The application of a preload has been the main means of preventing loosening. However, this measure has not been able to eliminate its occurrence. In this study the effect of a washer in a Brånemark-type implant on the loosening conditions of the retaining screw was investigated using a finite element simulation. The simulation indicated that a washer may significantly increase the tolerance of a screw against loosening. This is accomplished by increasing the tolerance of the implant against deformation. The addition of a customized washer to a dental implant system may offer a very simple and inexpensive solution for the persistent problem of screw loosening.
Dental Abutments↗
Marginal discrepancy of screw-retained and cemented metal-ceramic crowns on implants abutments.
This in vitro study quantified the marginal discrepancy of the implant-to-prosthetic-crown interface on nonsubmerged dental implants restored with either a cemented or a screw-retained approach. Metal-ceramic crowns were fabricated for 20 ITI 4.1 x 10 mm solid-screw titanium implants. Ten implants received octa abutments and screw-retained crowns fabricated on premachined gold cylinders. The remaining 10 implants were restored with 5.5-mm solid abutments and metal-ceramic crowns cemented alternately with a glass-ionomer or a zinc phosphate luting agent. Inspection of the implant-crown interface was conducted using light microscopy under x 50 magnification at selected stages in the process of crown fabrication. Statistical analysis revealed a significant difference (P < .001) in the mean marginal fit between screw-retained (8.5 +/- 5.7 microns) and luted implant-supported crowns. This difference was observed both before (54.4 +/- 18.1 microns) and after cementation with glass-ionomer (57.4 +/- 20.2 microns) or zinc phosphate (67.4 +/- 15.9 microns).
Cementation↗
Osseointegration of rough acid-etched titanium implants: 5-year follow-up of 100 minimatic implants.
During 1992, 100 Minimatic screw implants made of titanium alloy (titanium-aluminum-vanadium) with a machined rough acid-etched surface were placed in 63 consecutive partially edentulous patients. At second-stage surgery, which was performed after a 4- to 6-month healing period, none of the implants showed signs of mobility, peri-implant infection, or bone loss from the crest of the ridge. Each patient was restored with a fixed prosthesis and reexamined every 3 months during the first year. Periapical radiographs were taken annually up to 5 years. These revealed no signs of peri-implant radiolucencies involving any of the implants, and mean alveolar bone loss was less than 1 mm at the 5-year examination. One implant was considered a late failure because of a peri-implant infection that developed during the first year, although the implant was still functional at year 5. Another patient with 2 implants dropped out during the fifth year of the study, although both implants had been considered successful up to that point. Based on annual measurements of Plaque Index, Sulcular Bleeding index, pocket probing depth, attachment level, width of keratinized mucosa, and hand-tested mobility, 97 of the remaining 98 implants were considered successful, resulting in a 98% success rate. This 5-year study confirms that Minimatic machined acid-etched implants provide predictable osseointegration results and supports the conclusion of other reports that titanium implants with a rough surface can fulfill the requirements of Albrektsson et al (1986) for implant success.
Alloys↗
Effect of cement space and delayed placement on the seating of crowns luted with Vitremer, Fuji Duet and Dyract Cem.
PURPOSE: To determine the effects of cement space and delayed placement on the post-cementation elevation of crowns luted with two resin-modified glass ionomer luting cements (Vitremer, Fuji Duet) and a self-curing polyacid-modified composite resin luting cement (Dyract Cem). MATERIALS AND METHODS: The investigation was conducted in two parts: (1) A loading apparatus was employed to simulate the seating of a crown on a die. Six dies, differing in the amount of cement space allowed from 6-52 microns, were used. The loading apparatus allowed for a test cement to be placed in the crown, and subsequent activation of the apparatus lead to seating of the die into the crown. After seating, post-cementation crown elevation was measured. The cements Phosphacap, Vitremer, Dyract Cem and Fuji Duet were used. Each cement was tested 10 times at each of the six cement spaces. The post-cementation crown elevation data was analyzed by one- and two-way ANOVA tests, and Tukey's HSD test. (2) The cements Vitremer, Fuji Duet and Dyract Cem, were tested in a similar fashion to Part 1, except activation of the loading apparatus was delayed. Three cement spaces (6, 29 and 52 microns) and three delay periods (60, 120 and 180 seconds) were investigated. Each cement was tested five times. The post-cementation crown elevation data was analyzed by one- and two-way ANOVA tests, and Tukey's HSD test. RESULTS: The amount of cement space provided and the cement used significantly affected post-cementation crown elevation (P = 0.001). Where cementation was delayed, post-cementation crown elevation was significantly affected by both the cement used and the amount of cement space provided (P = 0.001). Delayed placement of Dyract Cem had no significant effect on post-cementation crown elevation (P = 0.01). Post-cementation crown elevation when Vitremer was used was significantly affected by both the amount of cement space and delayed placement (P = 0.01). A 180-second delay in placement of Vitremer resulted in significantly worse post-cementation crown elevation (P = 0.01). Seating was not possible 120 seconds after Fuji Duet had been mixed.
Analysis of Variance↗
Stability measurements of one-stage Brånemark implants during healing in mandibles. A clinical resonance frequency analysis study.
Using a one-stage surgical protocol, 75 implants ad modum Brånemark of three different designs were inserted in 15 edentulous mandibles of high bone density. All implants were followed with repeated stability measurements by means of resonance frequency analysis (RFA) from implant placement to connection of the fixed prostheses (3-4 months), in order to evaluate possible stability changes during healing. It was shown that the resonance frequency (RF) values slightly decreased for the majority of the implants during the study period independent of design. Consequently, the results of the present study indicated that the implants were as stable at time of placement as when measured at 3-4 months post-surgery, i.e. when the prostheses were attached. The available data support the concept of direct loading of implants when inserted between the mental interforaminal regions. One implant failed during healing and the corresponding RF measurement disclosed, at six weeks post-surgery, a value being far below the one registered at implant placement. The lowered RF value indicated the failure several weeks before the mobility was clinically diagnosed. The presence or absence of a fixture/abutment junction did not exert any influence on the marginal bone level, as determined radiographically at the end of the short investigation period.
Aged↗
Clinical and microbial findings on osseo-integrated implants; comparisons between partially dentate and edentulous subjects.
Clinical and microbiological parameters in partially dentate and edentulous patients treated with oral implants were compared in this study. Twenty-four subjects including 9 males and 15 females, aged 33 to 70 were treated with 98 Brånemark fixtures. Plaque index, gingival index, pocket depth, implant mobility and crevicular fluid flow rate were measured. Latex agglutination tests identified the presence of Actinobacillus Actinomycetem-comitans, Porphyromonas gingivalis and Prevotella intermedia. Partially dentate patients accumulated more plaque than edentulous patients (P = 0.05), whereas crevicular fluid flow rate was significantly higher (P < 0.001) in the partially dentate population. Porphyromonas gingivalis and Prevotella intermedia were more frequently detected (P < 0.01) in partially dentate patients. These results indicate that the presence of natural teeth alter clinical and microbiological parameters which could in turn affect the long term success rate of implants.
Adult↗
A technique for compensating for the loose CeraOne screw.
Clinical experience indicates that implant-supported crowns for the replacement of individual molars using the original, regular platform CeraOne protocol (Nobel Biocare) infrequently result in gold screws loosening. This article offers a technique that may prevent the CeraOne gold screw from working loose. It is intended to be a correction for a problem, not a first-time treatment. Also, this is a treatment that should be offered only after the prescribed Brånemark protocol for screw tightening and elimination of excursive contacts has proven ineffective.
Dental Abutments↗
Retrospective analysis of an implant system.
The reliability of dental implants results from a combination of design, placement, and reconstructive techniques. Retrospective analysis is one vehicle for evaluating implant success. This article presents the reliability of these techniques in Bicon dental implants. The survivability of this implant was evaluated retrospectively using life table survival analysis over a 10-year period in 13 practices. The parameters used for success included no implant loss, no mobility, no continuing bone loss that did not stabilize after 1 year, no discomfort, and no purulence.
Dental Abutments↗
Influence of bicortical or monocortical anchorage on maxillary implant stability: a 15-year retrospective study of Brånemark System implants.
The present study evaluated implant survival and marginal bone loss in maxillae over a 15-year follow-up period as a function of either monocortical or bicortical implant anchorage. Of 207 standard Brånemark implants (10 mm in length) followed, 110 implants were judged to be monocortically anchored and 97 as bicortically anchored. The bicortically anchored implants failed nearly 4 times more often than the monocortical ones. Implant fractures accounted for over 80% of the observed failures and were found to affect the bicortical group almost 3 times more often. As tentative explanations, induction of increased stress and bending forces resulting from possible prosthetic misfit, presence of unfavorable arch relationships, or high occlusal tables in combination with bicortically anchored implants have been suggested, all indicating an overambitious fixation of the bicortical anchorage. Total marginal bone loss was low over the 15-year period and close to identical for the 2 groups, suggesting that the mode of cortical anchorage did not have any clinically significant influence on marginal bone remodeling.
Adult↗
A survey of luting cements preferred by dental practitioners in the Commonwealth of Virginia.
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Dental Cements↗
Implant selection considerations and criteria.
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Decision Making↗
A prospective study to assess osseointegration of dental endosseous implants with the Periotest instrument.
Long-term studies have documented the successful treatment of edentulous and partially edentulous patients with titanium implants. However, the inability to identify some non-osseointegrated implants before occlusal loading is costly to practitioners and patients. This study followed all patients (n = 40) who had implants placed over a 6-month period. The Periotest instrument was used at Stage II surgery, final impression, prosthesis placement, and 6 and 12 months after occlusal loading to quantify mobility/lack of mobility of implants with conventional 1-piece temporary healing abutments in place. The positive predictive value was 64%. The Periotest instrument was able to identify non-integrated implants only when measured at Stage II surgery and 12 months after occlusal loading, 64% of the time. However, Periotest values recorded at Stage II surgery are not valid predictors of non-osseointegrated implants 12 months post-occlusal loading.
Adolescent↗
Evaluation of a single-tooth implant.
Fifty-nine commercially pure titanium implants in 59 subjects were compared with internal control teeth for 3 years. Nineteen coated implants of identical design were placed in 17 of the subjects and compared with the titanium implants. Demographic data, microbial DNA, aspartate aminotransferase levels, Plaque Index, width of adjacent keratinized tissue, probing depths, bleeding on probing, relative attachment levels, mobility, and radiographic bone height were studied. The only statistically significant changes over time were improved plaque scores in the subjects and slight bone loss around the implants. There were no differences between the 2 types of implants. Mobility was less and probing depth and bleeding on probing were greater in the implant sites than in the control sites.
Adolescent↗