前牙氧化锆全瓷粘接桥两年临床应用效果观察

目的 观察前牙氧化锆全瓷粘接桥的修复效果,为氧化锆全瓷粘接桥修复的适应证选择和临床应用提供参考.方法 选择23例单颌缺失1～2颗前牙的患者,进行单翼或双翼氧化锆全瓷粘接桥修复.随访时根据美国公共健康协会标准,观察粘接桥的完整性、边缘着色、继发龋和颜色匹配性.结果 共制作粘接桥29件,其中单翼粘接桥23件,双翼粘接桥6件.观察14～30个月,平均22个月.1件双翼粘接桥修复失败,2件单翼粘接桥修复失败.26件粘接桥无边缘着色,无继发龋,仅2件单翼粘接桥颜色偏白.粘接桥累积生存率为90%(26/29).结论 对单颌缺失1～2颗前牙的患者进行氧化锆全瓷粘接桥修复,可以达到恢复前牙美观和功能的效果.     

Clinico-statistical observation of various prosthetic restorations at the Prosthetic Department, Asahi University Hospital. 4. Circumstances concerning prosthetic method for missing teeth for the duration from April 1986 to March 1987

The statistics for prosthetic restorations used for missing teeth at the Prosthetic Department of Asahi University Hospital from April 1986 to March 1987 were compared with those obtained for an earlier period (April 1983 to March 1984). Fixed bridges and removable partial dentures constituted the majority of the prosthetic restorations for posterior teeth. Fixed bridges were twice more frequently used for anterior teeth during this period than during the previous period. For a single missing tooth, fixed bridges amounted to 90% and removable partial dentures to 10%, as they did in the previous period. For two or more missing teeth, the use of fixed bridges was some what increased compared to the previous period. As in the previous report, the use of so-called one-tooth denture was most frequent for missing lower first molar. For bridges, the average number of missing teeth and that of abutment teeth were 1.3 and 2.4 respectively. Bridges for one missing tooth with two abutment teeth were most frequently used. For removable partial dentures, the average number of missing teeth and that of abutment teeth were 6.1 and 2.8 respectively. Removable partial dentures for two missing teeth with two abutment teeth were most frequently used. Full cast crowns were most frequently used for bridge retainers, followed by facing crowns. Facing crowns were used more than twice as frequently during this period as they were during the previous period.(ABSTRACT TRUNCATED AT 250 WORDS)     

An analysis of stress around abutment teeth and periodontium in three-unit fixed partial dentures--photoelastic analysis with simulated periodontal ligament

The mechanical characteristics of zirconia, hybrid hard resin and dental metal for crowns and fixed partial dentures (FPD) have been researched for clinical applications. However, for these kinds of restorations, the distribution of mechanical stress around the abutment teeth and periodontium during function has not been sufficiently assessed. The aim of this study was to clarify the influence of these materials upon abutment teeth and periodontium through a two-dimensional photoelastic method. Two-dimensional simulation models of three-unit FPDs were constructed from these materials. By applying a force of 400 N vertically to these FPDs, the stress distribution around the abutment teeth and alveolar bone was analyzed and the fringe orders were recorded with a transmission polariscope. As a result, the fringe order values at the root dentin around the marginal area of the pontic joint were the highest in zirconia, and the smallest in hybrid hard resin. The spread of internal stress around the marginal area was larger in the hybrid hard resin model and dental metal model than in the zirconia model. This study suggested that differences in stress distribution within the abutment teeth and around the alveolar bone were related to differences in elastic coefficients of the materials used in FPDs.     

即刻牙本质封闭对预备后牙本质敏感程度的影响

目的评价牙本质即刻封闭技术对牙体预备后活髓基牙牙本质敏感程度的影响。方法30例患者行后牙三单位固定义齿修复,每例口内有2颗活髓后牙参与实验,基牙随机分为实验组和对照组。实验组在基牙预备后行即刻牙本质封闭,随后取模。对照组在基牙预备后常规取模,不进行即刻牙本质封闭。1周后行最终修复,全冠粘接后1周、1个月、6个月、12个月和18个月时检查记录患者的牙本质敏感程度,并进行统计学分析。结果固定义齿粘接后1周及1个月,实验组出现敏感基牙数少于对照组（1周：Z=-1.88,P=0.03;1个月：Z=-2.15,P=0.02）。粘接后6、12及18个月两组敏感发生率间差异无统计学意义（6个月：Z=-0.69,P=0.30;12个月：Z=-0.41, P=0.69;18个月：Z=-0.42,P=0.52）。比较两组敏感程度结果显示,实验组敏感的基牙,敏感程度主要为1度;对照组主要为1度及2度。1周及1个月观察点两组疼痛程度差异有统计学意义（1周：P＜0.05,1个月P=0.027）。结论活髓基牙牙体预备后行即刻牙本质封闭,可有效降低术后短期内牙本质过敏的发生率,减小患者的术后不适感。     

Survival rates of resin-bonded, glass fiber-reinforced composite fixed partial dentures with a mean follow-up of 42 months: a pilot study

STATEMENT OF PROBLEM: Although short-term clinical data exist for resin-bonded, glass fiber-reinforced composite fixed partial dentures (FPDs), long-term data are needed. PURPOSE: The survival rates of 29 resin-bonded, glass fiber-reinforced composite fixed partial dentures were evaluated in this clinical study for periods of up to 42 months. MATERIAL AND METHODS: FPDs were fabricated to replace 1 to 3 missing maxillary or mandibular teeth of 29 patients not able to be treated with conventional FPDs. Originally, there were 37 patients (the drop-out rate was 22%). The FPDs were retained with wings, inlays, complete coverage crowns, or combinations of these that were bonded to tooth structure. The FPD frameworks were made of continuous unidirectional E-glass fibers with a multiphase polymer matrix and light-polymerized particulate composite veneer. The patients were recalled for examinations, where a general dental examination was performed, 1 to 3 times per year for up to 63 months (minimum 24 months, mean 42 months). Partial or complete total debonding of the FPD or the framework fracture was considered a treatment failure. The data were analyzed with the Kaplan-Meier survival test (alpha=.05). RESULTS: Two resin frameworks fractured, and 3 frameworks were debonded. Kaplan-Meier survival probability at 63 months was 75%. Three of the failed FPDs were rebonded or repaired in situ, producing a functional survival rate of 93% after rebonding or repairing (mean survival time was 55 months). CONCLUSION: The results of this clinical study of 29 prostheses suggest that glass fiber-reinforced FPDs may be a possible alternative to cast metal resin-bonded FPDs. These restorations were successfully used as multiple-unit prostheses that employed a variety of abutment tooth preparation designs.     

Effects of resistance form on attachment strength of resin-retained castings

This study evaluated the effects of tooth preparation design on resistance to dislodgment of a resin-bonded fixed partial denture (RBFPD). The variations of tooth preparation tested included axial coverage, retentive grooves, and an occlusal rest. Patterns of the tooth preparation designs were prepared and cast in a base metal alloy. Retainer patterns were waxed to refractory casts of metal dies, cast, finished and then bonded to the dies. The complete assemblies were loaded to failure on an Instron mechanical testing machine, and analysis indicated that retainers with occlusal rests were the most resistant. Grooves provided no statistically significant increase in resistance to failure of the cement. Increased axial coverage did not increase resistance to dislodgment. Successful fixed partial dentures (FPDs) depend on cast retainers to resist displacement of the restoration during function. Introduction of resin-bonded restorations opened the possibility of FPDs with minimal reduction of abutments. Specific questions concerning long term success and tooth preparation designs were prominent concerns. The influence of resistance form on overall stability of a restoration was also of particular interest. Buonocore established the foundation for retention of composite resins to acid-pitted enamel. Rochette used this technology to bond perforated cast metal splints to periodontally compromised teeth. A mechanical interlock was created as composite resin engaged these perforations and sustained the cast splint to acid-etched enamel. Howe adapted this design for replacement of anterior teeth by adding porcelain to a metal ceramic framework and then bonding the framework to abutments without tooth preparations. The advantages of these procedures were their conservative nature, esthetics, and ease of rebonding after dislodgment. Livaditis and Thompson adapted the procedure proposed by Tanaka of corrosion-pitting the bonding surface of a base metal alloy. They increased the surface area to be bonded, eliminated the perforations to improve rigidity of the framework, and described tooth preparation modifications of the abutments. They suggested an occlusal rest, establishment of guide planes through axial reduction, and a proximal extension to the facial surface to resist lingual displacement. Simonson, et al., based their anterior tooth preparation design on the configuration suggested by Livaditis which included a slight chamfer finish line plus reduction of the lingual surface to provide a thicker metal framework. Barrack introduced an inlay type tooth preparation for the occlusal rest plus shallow vertical proximal grooves, and Meiers used grooves as an esthetic alternative to proximal extensions. Clinical studies and surveys have identified specific variables involved with success and failure, while in vitro studies have evaluated framework designs, bonding agents, and methods for pitting the metal surface. This study evaluated resistance of RBFPDs to dislodgment of different tooth preparation designs.     

The use of endodontically treated and/or fiber post-retained teeth as abutments for fixed partial dentures

The purpose of this in vitro study was to evaluate the effect of endodontic treatment with or without fiber-post restorations on the fracture strength of abutment teeth under fixed partial dentures (FPDs). Seventy extracted premolar and canine teeth were used. Groups of fiber-post-retained and root-filled teeth were endodontically treated. The teeth were embedded in an acrylic resin perpendicular to the horizontal plane to create fixed partial dentures. The following groups were created using different abutments: (1) sound (S) canine/S premolar, (2) S canine/endodontically treated (ET) premolar, (3) ET canine/S premolar, (4) ET canine/ET premolar, (5) S canine/fiber-post-restored (FPR) premolar, (6) FPR canine/S premolar, and (7) FPR canine/FPR premolar. Each tooth was prepared for a complete-coverage full-metal crown. Impressions were taken; metal frameworks were fabricated and cemented. The samples were exposed to 5,000 cycles of thermomechanical fatigue and loaded compressively until fracture (2?mm/min). The data were statistically analyzed using (Kruskal-Wallis test, α?=?0.05). No significant difference was found among the mean fracture strengths of the groups (p?=?0.696). There were distinct differences in failure patterns. All of the fracture types were horizontal, and neither vertical nor non-restorable root fractures were recorded. Premolars seemed to be a critical abutment compared to canines when they were sound under FPDs. The percentage of cervical fractures was high in endodontically treated teeth when compared to post-retained groups. In case of post-debonding, the abutment fracture did not occur. When root-filled teeth are used as abutments for FPDs, fiber-post restorations or the creation of abutments from similar structures (ET/ET or FPR/FPR) results in improved conservation of root structure under loading when compared to the abutments from different structures (S/ET, ET/S, FPR/S, S/FPR).     

Short-term clinical evaluation of a resin-modified glass-ionomer luting cement.

OBJECTIVES: Resin-reinforced glass-ionomer cements were developed by adding resin components to conventional glass-ionomer cement. This improved physical properties and bonding characteristics. FujiCEM is the first paste-paste-type resin-modified glass-ionomer luting cement that enables consistent mixture. The purpose of this study was to evaluate the short-term clinical performance of FujiCEM, which was used for final cementation of indirect restorations, such as inlays, crowns, and fixed partial dentures. METHOD AND MATERIALS: A total of 290 restorations (165 crowns, 71 inlays, 15 onlays, 36 fixed partial dentures, 3 implant superstructures) were placed in 268 patients (137 males, 131 females) with a mean age of 54.4+/-13.0 years. Restorations were luted with FujiCEM mixed for 10 seconds after the teeth surfaces were treated with a conditioner containing 10% citric acid and 2% ferric chloride for 20 seconds, washed, and dried with gentle air flow. Out of the investigated 337 teeth, 99 (29%) teeth were vital, and 238 (71%) were nonvital. These restorations were followed up for a period of 21 months. All the restorations were evaluated for postoperative sensitivity, secondary caries, gingival condition, and pocket depth. RESULTS: No clinical failures (eg, dislodgment, secondary caries, irritation of soft tissue, and postoperative sensitivity) were observed. CONCLUSION: FujiCEM had promising clinical performance with inlays, crowns, onlays, fixed partial dentures, and implant superstructures at 21 months after service.     

Performance of ceramic laminate veneers with immediate dentine sealing: An 11 year prospective clinical trial

ObjectiveIn this prospective clinical trial the survival, success rate and patient satisfaction of ceramic laminate veneers with special interest on existing restorations, immediate dentin sealing and endodontically treated teeth was evaluated.MethodsA total of 104 patients (mean age: 42.1 years old) received 384 feldspathic ceramic laminate veneers on maxillary anterior teeth. Veneer preparations with incisal overlap were performed using a mock up technique. Existing resin composite restorations of acceptable quality were not removed but conditioned using silica coating and silanization. Immediate dentin sealing (IDS) was applied when more than 50% of dentin was exposed during preparation. Endodontically treated teeth were not excluded. After adhesive cementation, restorations were evaluated by calibrated evaluators at baseline and final follow-up using modified USPHS criteria.Results225 Laminate veneers were bonded onto teeth without existing restorations, 159 on teeth with pre-existing resin composite restorations, 87 to teeth with more than 50% of exposed dentin surface and 43 to endodontically-treated teeth. In total, 19 failures were observed in form of debonding (n = 3), fracture (n = 15) and extraction due to endodontic complications (n = 1). In teeth with more than 50% of dentin exposure, a significant increase in survival rate was observed when IDS was used (96.4% versus 81.8%). No significant difference was found between teeth with and without pre-existing composite resin restorations (84.6% versus 95.5%) or between vital and non-vital teeth (95.6% versus 88.1%). Laminate veneers luted to endontically-treated teeth had a significant mis-match in color compared to vital teeth. Patients who smoked presented with significantly more marginal discoloration, but no intervention was needed. Patients scored favorably values on the Oral Health Impact Profile questionnaire and were generally satisfied with the treatment. In this clinical trial, the ceramic laminate veneers had a relatively high survival rate.SignificanceTeeth with more than 50% of dentin exposure significantly benefit from IDS. Pre-existing restorations or endodontic treatments do not have an effect on the survival rate of ceramic laminate veneers. However, smoking habits and previous endodontic treatments negatively affect the success rate due to color changes.Clinical Trial Registration Number: NCT03645551     

Predictable success with resin bonded fixed partial dentures

The conservative nature of the resin bonded fixed partial denture is the reason it is used. The ability to replace a missing tooth while avoiding aggressive preparation of the abutment teeth is a desirable concept. The use of conservative preparation forms will aid in the long term predictable success of the resin bonded fixed partial denture.     

Complications and failures in removable partial dentures: a clinical evaluation

The design of removable partial dentures (RPDs) is an important factor for good prognostication. The purpose of this study was to clarify the effectiveness of denture designs and to clarify the component that had high rates of failure and complications. A total of 91 RPDs, worn by 65 patients for 2-10 years, were assessed. Removable partial dentures were classified into four groups: telescopic dentures (TDs), ordinary clasp dentures (ODs), modified clasp dentures (MDs) and combination dentures (CDs). The failure rates of abutment teeth were the highest and those of retainers were the second highest. The failure rates of connectors were generally low, but they increased suddenly after 6 years. Complication and failure rates of denture bases and artificial teeth were generally low. Complication and failure rates of TDs were high at abutment teeth and low level at retainers. Complication and failure rates of ODs were high at retainers.     

Thirteen-year follow-up study of resin-bonded fixed partial dentures.

OBJECTIVE: The technique of resin-bonded fixed partial dentures (RBFPD) is a well-accepted clinical technique to replace missing teeth. The survival rates reported in the literature vary widely, and the conclusions are sometimes conflicting. This study presents the clinical long-term performance of silicoated RBFPDs and also determines the main cause of failure. METHOD AND MATERIALS: Sixty-one patients with a total of 74 RBFPDs were either examined or requested to complete a questionnaire regarding their fixed partial dentures. Sixty-four were placed in the anterior region, and 10 in the posterior region. No more than one missing tooth in the posterior area and two missing teeth in the anterior region were replaced with RBFPDs. A retentive preparation was made on the abutment teeth. All the RBFPDs were adhesively seated. RESULTS: Eighteen RBFPDs failed after a mean observation time of 7.8 years (nine retention losses of one or more retainers, six carious lesions, and three veneer fractures occurred). Seven RBFPDs were rebonded, whereas the remaining 11 failures had to be replaced with conventional FPDs. Fifty-six RBFPDs were primary restorations, and seven secondary RBFPDs were used after the loss of the primary restoration. A mean survival rate better than 69% after a 13-year observation period was calculated. Including the rebonded restorations, a mean functional survival rate of 83% was estimated. A total of 18 failures (24.3%) of all restorations were observed, the main cause being loss of retention. CONCLUSION: Silicoated RBFPDs are a viable treatment means with an acceptable success expectancy.     

Effect of direct retainer and major connector designs on RPD and abutment tooth movement dynamics

Designs of removable partial dentures are suggested to affect the mobility of abutment teeth and removable partial denture (RPD) during oral functions. This study aimed to examine the effect of direct retainer and major connector designs on RPD dynamics under simulated loading. Six different Kennedy class II maxillary RPDs were fabricated on a maxillary model. These dentures involved 3 different direct retainers (wrought-wire clasp, RPA clasp, and conical crown telescopic retainer) and 2 different major connectors (Co-Cr major connector and heat-cured acrylic resin with a metal strengthener). Using an experimental model with simulated periodontal ligaments and mucosa that were fabricated using silicone impression material, three-dimensional displacements of the RPDs were measured under a simulated 30-N loading with a displacement transducer type M-3. Significant effects of "direct retainer design" on bucco-palatal displacements and "major connector" on mesio-distal displacements were revealed by 2 x 3 two-way analysis of variance of abutment teeth movements (P < 0.001 and P = 0.002, respectively). Additionally, analysis of variance of RPD displacements revealed significant effects of "direct retainer design" on corono-apical displacements and "major connector" on mesio-distal displacements (P = 0.001 and P = 0.028, respectively). Rigid direct retainers and rigid major connectors decrease the movements of both abutment tooth and RPD.     

Complications and primary failures related to fixed metal ceramic bridge prostheses made by dental students

SUMMARY Porcelain fused to metal provides better aesthetics in fixed partial dentures than veneers with gold‐resin that were used formerly. The aim of our study was to evaluate complications and primary failures of fixed metal ceramic bridge prostheses made by dental students. We studied 61 patients (32 women, 29 men, mean age 49 years, range 28–73 years) treated during years 1990–1993. Data were collected from the patient files. Altogether 82 bridges were made (mean 4·1 units, range 2–6), 221 abutments (mean 2·7, range 2–6) and 136 pontics (mean 1·6, range 1–4). Forty‐seven cast cores were used in 29 bridges (mean 0·4 cores, range 1–3) and semiprecious attachments as an extra attachment in two bridges. Seven teeth were extracted due to complication and/or failure during endodontic treatment and root canal perforation during preparation. In two cases the abutment tooth was fractured by removing the old crown. Four unsuccessful bridges were remade and in seven cases the firing of porcelain was renewed. The study concludes that most common failures of fixed metal ceramic bridges made by dental students occur during root canal preparation of abutment teeth.     

Influence of framework design on fracture strength of mandibular anterior all-ceramic resin-bonded fixed partial dentures

PURPOSE: The purpose of this in vitro study was to evaluate the influence of the framework design on the fracture strength of all-ceramic resin-bonded fixed partial dentures (RBFPD) in the mandibular incisor region. MATERIALS AND METHODS: Twenty-four aluminum oxide ceramic frameworks were copy milled with the Celay system, glass infiltrated, and veneered with feldspathic porcelain to replace a mandibular incisor. Forty-eight extracted human incisors were used as abutments by embedding them in a polyester resin. The master casts were fabricated according to a typical clinical case. The sandblasted restorations were bonded to the acid-etched abutment teeth with a composite resin. Twelve RBFPDs had a conventional two-retainer design, and 12 had a cantilevered single-retainer design. Subgroups of eight specimens were subjected to a quasistatic load in the direction of the long axis of the abutment teeth in a universal testing machine. Additional subgroups of four specimens were subjected under 0 degrees to dynamic loading of 25 N in a dual-axis chewing simulator. RESULTS: The mean fracture strengths under quasistatic loading were 313 N (SD 42) for the two-retainer design and 291 N (SD 100) for the single-retainer design. The mean cycles sustained by specimens subjected to dynamic loading at 25 N were 50,081 (SD 42,705) for the two-retainer design and 297,099 (SD 508,439) for the single-retainer design. There was no statistically significant influence of the framework design on the fracture strength of the restorations under quasistatic or dynamic loading. CONCLUSION: The clinical application of cantilevered all-ceramic RBFPDs in the mandible may be an alternative to all-ceramic RBFPDs with two retainers.     

A nine-year clinical case study of a resin-bonded fixed partial denture seated on the maxillary anterior teeth

PatientThis report describes the longevity of a resin-bonded fixed partial denture (RBFPD). This denture was seated on the maxillary anterior teeth with minimal tooth preparation. The RBFPD was cast from a silver–palladium alloy (Castwell M.C. 12), and the pontic was veneered with an indirect composite material (Estenia). The retainers were primed with a metal conditioner (V-Primer) and seated with a tri-n-butylborane initiated adhesive resin (Super-Bond C&B). After an observation period of eight years, a fracture occurred in the incisal edge of the central incisor abutment. The fractured area was restored with light-polymerizing composite resin and the anterior guidance was re-adjusted.DiscussionRBFPD abutment teeth with deep vertical overlap should be carefully prepared to avoid abutment tooth fracture.ConclusionThe clinical performance of the RBFPD made from a silver–palladium–copper–gold alloy was sufficient when seated with tri-n-butylborane initiated adhesive resin after surface modification using vinyl-thiol primer.Clinical significanceThe use of vinyl-thiol primer and tri-n-butylborane initiated adhesive resin is a clinically reliable bonding system for seating resin-bonded fixed partial denture (RBFPD) made from a silver–palladium–copper–gold alloy. The RBFPD, based on a reliable bonding system, can clinically function for a long time, even if the vertical overlap of the abutment teeth is excessive.     

Three-year clinical evaluation of fiber-reinforced composite fixed partial dentures using prefabricated pontics

PURPOSE: The purpose of this study was to evaluate the clinical performance of surface-retained adhesive composite fixed partial dentures reinforced by an ultra-high molecular weight polyethylene (UHMWP) fiber (Ribbond THM). MATERIALS AND METHODS: Twenty-three surface-retained fiber reinforced composite (FRC) fixed partial dentures (FPD) were placed by two operators in 23 patients, each with a single missing tooth. The restorations included prefabricated composite resin pontics, and no preparations were done on the lingual surfaces of the abutment teeth. The patients were recalled for examinations every year for up to 3 years. Restorations were evaluated directly using the modified Ryge criteria. The minimum observation period was 1 year and the maximum observation period was 3 years. RESULTS: At baseline, 23 restorations were graded as Alpha for all parameters. At one year and two years (n = 21), three Bravos for wear resistance and surface texture/gingival inflammation and two Bravos for color match were observed. Twenty-one of 23 restorations were retained at the end of two years (91.3%) and 78.3% were retained after a maximum of 3 years. CONCLUSION: The results of this clinical study suggestthat UHMWP FRC FPDs are quite acceptable at least forthree years. However, further clinical investigations are still needed for improved long-term clinical performance.     

Failures and length of service in fixed prosthodontics after long-term function. A longitudinal clinical study

In this long-term clinical study, the outcome of prosthetic restorative treatment was evaluated by examining fixed partial dentures 14 years after insertion. All prosthetic treatments had been performed by private general practitioners. The investigation comprised a total of 97 patients rehabilitated with 140 fixed reconstructions with and without cantilever extension. At the time of the examination 17% (24) of the original fixed restorations had been removed completely owing to loss of retention in most cases. Other technical failures were also recorded, including framework fractures and loose retainers. The total incidence of failure, biological ones excluded, was 26%. The incidence of failure for restorations with cantilever extension, was higher than that for fixed partial dentures with a distal abutment tooth. No significant difference in the rate of technical failure or loss of serviceability was found between the different age classes. After 14 years in service, 83% of the extensive fixed partial dentures were still functioning and fully serviceable, an overall result considered to be highly satisfactory.     

Ultrasonic debonding of composite-retained restorations

Ultrasonic chisels are used clinically to remove composite-retained bridges from one or both abutment teeth. Displacement amplitude measurements at the tip of the two designs available showed that the curved chisel was twice as powerful as the straight chisel. Investigations were undertaken to assess the efficiency of these chisels in vitro. Cast metal retainers were made, which incorporated particulate roughening of the fitting surface and these were bonded with a composite luting cement to extracted premolar teeth. Ten clinicians were asked to remove the retainers from the teeth and their application forces were measured. Clinicians were able to apply the highest force with the straight chisel design. The time taken to remove the retained restorations under increasing application forces and different power settings of the two chisels was then measured. Optimal time for removal of the retainers (ie with 5-10 minutes' exposure) required the use of high displacement amplitudes of the chisel, together with high application forces. Scanning electron microscopy of the failed bond revealed that composite was removed in those areas where the chisel was applied to the tooth. However, there was a disproportionate amount of tooth surface damage compared to that inflicted upon the metal retainer.     

Survival rate of endodontically treated teeth with posts after prosthetic restoration

The purpose of this retrospective clinical study was to evaluate the survival rate of teeth that were endodontically treated and restored with endodontic posts and prosthodontic restorations. A total of 864 teeth in 360 patients were included in the study. Dental records and radiographs of the patients were evaluated and four parameters were documented. The parameters were type of post, type of prosthodontic restoration, observation time, and, in cases of failure, failure mode. Statistical survival analyses were performed according to Kaplan-Meier. The mean observation time was 22.5 +/- 14.9 months. The calculated survival rates of the abutments were statistically significant different for fixed partial dentures (FPDs) and for removable partial dentures (RPDs) with survival rates of 92.7% and 51.0% after 60 months, respectively. Most of the presumed factors influencing the survival rate of endodontically treated abutment teeth only affected the outcome in the RPD group. Teeth restored with post and cores present a high risk for failure when used as abutments for conical-double-crown-retained RPDs.