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Cement failure loads of 4 provisional luting agents used for the cementation of implant-supported fixed partial dentures.

The major disadvantage of cement-retained implant-supported fixed partial dentures (FPDs) is difficulty in retrievability. The retentive strengths of the provisional luting agents usually employed in these cases are therefore an important consideration. This study evaluated the cement failure loads of 4 provisional luting agents used for the cementation of FPDs supported by 2 implants or 4 implants. Nogenol luting agent exhibited the lowest retentive values in both types of FPD. ImProv proved to be the most retentive cement of all tested. Temp Bond NE and Temp Bond presented significantly different values (P < .05) for the 2-implant FPD, but not for the 4-implant model. On the basis of the study results, it may be concluded that Nogenol appears to be more appropriate for cementation of both 2- and 4-implant-supported FPDs when removal of the provisionally cemented superstructure is anticipated.

Analysis of Variance↗

Cemented versus screw-retained implant-supported single-tooth crowns: a 4-year prospective clinical study.

PURPOSE: The purpose of this controlled prospective clinical study was to compare cemented and screw-retained implant-supported single-tooth crowns followed for 4 years following prosthetic rehabilitation with respect to peri-implant marginal bone levels, peri-implant soft tissue parameters, and prosthetic complications. MATERIALS AND METHODS: Twelve consecutive patients were selected from a patient population attending the Implantology Department at the University of Padova. They all presented with single-tooth bilateral edentulous sites in the canine/premolar/molar region with adequate bone width, similar bone height at the implant sites, and an occlusal scheme that allowed for the establishment of identical occlusal cusp/fossa contacts. Each patient received 2 identical implants (1 in each edentulous site). One was randomly selected to be restored with a cemented implant-supported single-tooth crown, and the other was restored with a screw-retained implant-supported single-tooth crown. Data on peri-implant marginal bone levels and on soft tissue parameters were collected 4 years after implant placement and analyzed to determine whether there was a significant difference with respect to the method of retention (cemented versus screw-retained). RESULTS: All patients completed the study. All 24 implants survived, resulting in a cumulative implant success rate of 100%. Statistical analysis revealed no significant differences between the 2 groups with respect to peri-implant marginal bone levels and soft tissue parameters. DISCUSSION: The data obtained with this study suggested that the choice of cementation versus screw retention for single-tooth implant restorations is likely not based on clinical results but seems to be based primarily on the clinician's preference. CONCLUSIONS: Within the limitations of this study, the results indicate that there was no evidence of different behavior of the peri-implant marginal bone and of the peri-implant soft tissue when cemented or screw-retained single-tooth implant restorations were provided for this patient population.

Alveolar Bone Loss↗

Failure rates of restorations for single-tooth replacement.

Failure rates of traditional fixed partial dentures, resin-bonded prostheses, and implant restorations for the replacement of a single missing tooth are compared in this literature review. A lack of documented longevity studies involving conventional fixed partial dentures makes failure rates difficult to determine. Reported failures ranged from only 3% over 23 years to 20% over 3 years. The major causes of loss were caries and endodontically and periodontally related complications. Research concerning resin-bonded fixed partial dentures was more prevalent, but indicated that overall retention of these prostheses may be unpredictable. Failure rates were quite divergent, ranging from 10% over 11 years to 54% over 11 months. Debonding was the usual cause of failure. Clinical reports of single-tooth implant replacements have followed stricter protocols than the other two alternatives. Short-term studies indicated favorable success rates for these restorations, but these must be confirmed by long-term evaluations. Failures ranged from 9% over 3 years to 0% over 6.6 years. These comparisons should be considered in treatment planning a restoration for the replacement of a single missing tooth.

Dental Prosthesis Retention↗

Telescopic crowns as attachments for implant supported restorations: a case series.

The use of dental implants to support mandibular or maxillary overdentures is a widely used treatment modality. Advantages are an increase in retention, an increase in chewing ability, and easy access for oral hygiene procedures. While telescopic and conical crowns have been used for decades to connect natural teeth to overdentures, not many cases have been reported in the literature of telescopic crowns placed on implants to support overdentures. This article describes 7 patients with overdentures supported by telescopic crowns who received 65 implants (ITI Straumann). The cases presented in this report have been in function for up to 4.5 years. During that time no adverse events were reported. The use of telescopic crowns as attachments for implant-supported overdentures may be a viable treatment option.

Adult↗

Clinical effectiveness of mandibular implant-retained overdentures.

INTRODUCTION: The literature reports that the treatment of fully edentulous mandibles with implant-retained overdentures has become a recognised form of therapy: however long-term data on the success are limited. The aim of the present study was to describe the clinical effectiveness of mandibular implant-supported/retained overdentures in the management of a group of edentulous patients. MATERIALS AND METHODS: The study group consisted of 59 consecutive edentulous patients attending the clinic of prosthetic dentistry at Cardiff Dental Hospital, who had been provided with implants in the mandible for complete overdenture retention. Several clinical parameters were examined in each patient: mobility of each implant, probing pocket depth, the presence or absence of plaque and calculus on each implant, bleeding index, marginal bone loss, jaw bone quality and quantity, complications that had occurred with the implants and patients opinions of the treatment. DISCUSSION: Of implants placed, 97% remained in function. Three fixtures had been lost. There was a high frequency of bleeding on probing. Complications associated with treatment included damage or looseness of abutment screws, fracture of the bar, entrapment of food beneath the overdenture and looseness of the opposing non-implant-retained complete denture. CONCLUSION: In general a very high degree of patient satisfaction with the implant-retained overdentures was recorded.

Adult↗

Spark erosion: a sophisticated technique to solve a difficult problem.

Even with the most careful planning, situations arise that require sophisticated treatment alternatives. The Milled Bar, of which the spark erosion bar is one type, is described in detail. A two-degree tapered meso (primary) bar with anterior friction pins attached to osseointegrated implants provides frictional retention when supporting a secondary bar with swivel lock attachments. The two components of the prosthesis are accurately associated with each other using spark erosion and plasma arc welding technology.

Dental Implantation, Endosseous↗

Mandibular overdentures stabilized by Astra Tech implants with either ball attachments or magnets: 5-year results.

PURPOSE: The purpose of this work was to report on the use of implant-stabilized overdentures in the mandible using the Astra Tech implant system with either ball attachments or magnets as the retentive mechanism. MATERIALS AND METHODS: Mandibular overdentures that used ball attachments on 2 implants were provided for 13 edentulous patients; 12 edentulous patients were provided with mandibular overdentures with magnet retention, using 2 implants in 10 patients and 3 implants in 2 patients. Once they were comfortable, the participants were placed on annual recall. Any other visits were initiated by the patients. Detailed records were kept for all visits. At the annual recall the following parameters were monitored: plaque levels, mucosal health, marginal bone levels, and the patients' assessment of the treatment. The patients were followed for 5 years. RESULTS: There was no statistical difference between the 2 groups for mucosal health and postinsertion maintenance. The magnet group had more abutment surfaces covered with plaque. Statistical analysis of the patients' subjective assessment of their treatment showed that the magnet group was less comfortable and chewing was less effective. CONCLUSION: The results indicate that both ball attachments and magnets used on isolated Astra Tech implants in the mandible are viable treatment options. Both attachment mechanisms provided patient satisfaction, although the ball attachments were better in this respect than the magnets.

Adult↗

Comparison of uniaxial resistance forces of cements used with implant-supported crowns.

PURPOSE: Provisional cements are commonly used to facilitate retrievability of cement-retained fixed implant restorations. While the functional life spans of these cements are unpredictable, the relative retentiveness of various permanent and provisional cements between dental alloys and titanium abutments is not well documented. The aim of this study was to compare the uniaxial resistance forces of permanent and provisional luting cements used for implant-supported crowns. MATERIALS AND METHODS: Seven samples on 4 different abutments (a total of 28 crowns) were cast using a gold-platinum-palladium alloy. The crowns were cemented with 3 different provisional, polycarboxylate, and glass-ionomer cements and 1 zinc phosphate cement. After storage of samples in artificial saliva for 24 hours, tensile tests were performed. RESULTS: While the highest uniaxial resistance forces were recorded for polycarboxylate cements, provisional cements exhibited significantly lower failure strengths (P < .05). The uniaxial resistance force of cements on different abutments exhibited notably different trends; however, more force was required to remove crowns cemented to long abutments (P < .05). DISCUSSION: Glass-ionomer and zinc phosphate cements may be used to increase the maintenance of implant-supported crowns. Temporary cementation of such restorations may necessitate frequent recementation, particularly for restorations on short abutments. CONCLUSIONS: Temporary cementation may be more suitable for restorations supported by multiple implants.

Analysis of Variance↗

Ten-year results of a prospective study using porous-surfaced dental implants and a mandibular overdenture.

BACKGROUND: Numerous investigators have used osseointegrated dental implants as retention for mandibular overdentures, but few have reported 10-year outcomes or incorporated carefully standardized radiographs to document crestal bone loss. PURPOSE: The purpose of this study was to use a prospective clinical trial design to assess the performance of short sintered porous-surfaced dental implants with a mandibular complete overdenture when all patients in the trial had undergone 10 years of continuous function. MATERIALS AND METHODS: Fifty-two fully edentulous patients, most with advanced alveolar ridge resorption, each received three free-standing Endopore implants (7-10 mm in length, mean length, 8.7 mm; Innova Corporation, Toronto, ON, Canada) in the mandibular symphysis region. After 10 weeks of submerged healing, these implants were used to support an overdenture. Carefully standardized radiographs, using a customized stainless steel filmholder attached to each implant and the x-ray tube, were collected at baseline, 3 months, 6 months, yearly to 5 years, and then again at 7and 10 years. RESULTS: Life table analysis revealed a 10-year implant survival of 92.7% and a mean annual bone loss after year 1 of 0.03 mm. CONCLUSION: Short free-standing dental implants with a sintered porous surface used for implant fixation are a predictable and effective means of retaining a mandibular overdenture in patients with advanced mandibular ridge resorption.

Alveolar Bone Loss↗

Retention of cemented implant-supported restorations.

PURPOSE: This investigation compared cement failure loads of a gold cylinder luted to a CeraOne titanium abutment (5-mm-high chimney) 24 hours postcementation when either zinc phosphate, Tempbond NE, or Tempbond luting agent was used. MATERIALS AND METHODS: Luting agent (0.01 mL) was applied to the internal aspect of the gold cylinder, and the cylinder was seated with finger pressure followed by a load of 5 kg for 10 minutes. The specimens were stored in 100% humidity at 37 degrees C for 24 hours before a uniaxial tensile force was applied to the gold cylinder by a mechanical testing instrument. A load-displacement chart was plotted and the cement failure load (CFL) calculated in kilograms. CFLs were determined for each luting agent with the access opening for the CeraOne gold screw on the internal of the abutment either unfilled or filled with autopolymerizing resin. RESULTS: A two-way ANOVA and Turkey's HSD revealed that zinc phosphate resulted in significantly higher (p < .05) mean CFLs than Tempbond or Tempbond NE. In general, filling the access opening did not affect mean CFLs for zinc phosphate and Tempbond NE. However, mean CFLs for gold cylinders cemented with Tempbond and a filled access opening were significantly higher than mean CFLs with an unfilled access opening. However, neither the filled nor the unfilled Tempbond group mean CFL was significantly different from either Tempbond NE mean CFL. CONCLUSIONS: Twenty-four hours postcementation, zinc phosphate luting cement significantly enhanced CFLs of a CeraOne gold cylinder luted to a 5-mm CeraOne titanium abutment compared with Tempbond and Tempbond NE. Filling the gold screw access opening of the abutment with autopolymerizing resin only led to higher mean CFLs when Tempbond was used as the luting agent. Filling the access opening had no effect (p > .05) on mean CFLs when Tempbond NE or zinc phosphate was used.

Analysis of Variance↗

Comparison of 7 luting protocols and their effect on the retention and marginal leakage of a cement-retained dental implant restoration.

PURPOSE: To determine the cement bond strength and marginal leakage of castings cemented to implant abutments. MATERIALS AND METHODS: Fifty-six titanium abutments and castings were divided into 7 groups (n=8), 1 for each cement. Castings were cemented to abutments using 1 of 3 resin-based cements (RES, RES-B, and RES-B-P), a resin-modified glass ionomer (GI), a polycarboxylate cement (PCB), an acrylic urethane cement (UDM), or a zinc phosphate cement (ZP). Specimens were placed in 100% humidity at 37 degrees C for 24 hours. Specimens were subjected to compressive load cycling followed by thermal cycling; they were then immersed for 24 hours in 0.5% basic fuchsin. Castings were removed with an Instron universal testing machine with a crosshead speed of 0.125 cm/min. Leakage was visually graded from 0 (no leakage) to 2 (leakage extended beyond the lower half of the internal surface of the casting). Failure load (FL) was analyzed with analysis of variance and Scheffe's test (alpha = .05). Chi-square was used to analyze leakage (alpha = .05). RESULTS: Cements were categorized by FL into 4 statistically unique groups: (1) RES-B-P (351 N) and GI (337 N); (2) ZP (245 N) and RES-B (241 N); (3) PCB (107 N); and (4) RES (63 N) and UDM (55 N). Leakage was greater for the PCB group than for the other groups (7 of 8 specimens demonstrated leakage; P < .01). Three ZP specimens demonstrated leakage. UDM and RES each had 1 specimen with leakage. RES-B-P, RES-B, and GI showed no leakage. CONCLUSIONS: Luting agents designated by the manufacturer as provisional cements demonstrated lower resistance to removal, regardless of material type. Luting agents described by manufacturers as "permanent" differed in resistance, with resin cements being most resistant, followed by zinc phosphate and polycarboxylate cements. Provisional cements demonstrated leakage comparable to higher-strength materials.

Dental Cements↗

A microscopical evaluation of 24 retrieved failed hollow implants.

Twenty-four hollow ITI implants (four screws, and 20 cylinders) were retrieved because of failure, and evaluated in our laboratory, in a eight-year period (1989-1996), to see if a common cause could be observed in this implant design. No selection of these implants was carried out, and they represented the total number of implants of this type received in the above-mentioned time frame. The implants had been inserted by several different clinicians and were received from four universities and a private practice. The implants had been removed for mobility, pain, and presence of a vertical bone loss. About two-thirds of the implants were unstable in the jaw at the time of retrieval. Twenty implants had been used as single implants restoration and four in bridge reconstructions. Most of our specimens showed that the inflammatory process had reached the hollow portion of the implants. The following microscopical features were present in almost all our specimens: calculus and plaque on the coronal portion of the implant surface, presence of proliferating epithelium and of bone sequestra, and presence of bone apically to the inflammatory process. Perhaps, when the inflammatory process reaches the implant hollow portion, the infection runs a more rapid course due to the scarce vascularity of the bone inside this part.

Dental Implants↗

Osseointegrated implants for single-tooth replacement: progress report from a multicenter prospective study after 3 years.

After 3 years, 82 of the original 92 patients remain in this prospective multicenter study of single-tooth restorations supported by Brånemark implants. Since the 1-year follow-up, 6 more patients have been lost, but no additional implants have failed in those patients examined at the 3-year follow-up visit. After 1 year of function, 97.2% of the implants survived in 88 patients, and between the 1- and 3-year follow-up, 100% survived in 82 patients, giving a 3-year cumulative success rate of 97.2%. No changes were observed in the status of gingivitis, pocket depth, periodontal pocket bleeding index, and tooth and implant mobility from those reported after 1 year. Marginal bone resorption remained at a low level--less than 0.1 mm annually during the second and third years. Abutment screw loosening continued, but at a significantly reduced rate from that reported after 1 year. When used, gold rather than titanium abutment screws remained secure.

Adult↗

Free-standing versus implant-tooth-interconnected restorations: understanding the prosthodontic perspective.

The surgical and prosthetic protocols for use of dental implants were originally developed for the treatment of complete edentulism. Implants are now widely used to treat partial edentulism, but the necessary adjustments to the prosthetic protocol have been developed largely on a trial-and-error basis. This paper reviews the efficacy of commonly used restorative techniques for partially edentulous arches and relates these techniques to Brånemark's original prosthetic protocol.

Dental Abutments↗