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It has been the purpose of this article to provide a rationale for the restoration of endodontically treated teeth. Treatment recommendations have been made in the areas of post design, placement technique, cements, core materials, and definitive restorations, based on a review of the clinical and laboratory data.
35 patients with aftereffects of cerebral stroke and 25 patients with hypertension were examined. A high rate of parodontal disease was revealed. An orthopedic stomatologic method of making metalloceramic dentures was devised.
STATEMENT OF PROBLEM: The concept of limiting taper has been described as a boundary between tapers that do and those that do not provide resistance form for a preparation. There is controversy as to whether this boundary that divides preparations with from those without resistance form translates clinically into a boundary for success. PURPOSE: This investigation evaluated the resistance form of abutments of crowns or retainers that have been dislodged to determine the clinical correlation between restoration dislodgment and lack of resistance form in the preparation. MATERIAL AND METHODS: Dies were fabricated from single crowns and retainers of fixed partial dentures that came loose and evaluated for resistance form. A total of 44 abutments were evaluated and included 1 incisor, 15 premolars, and 28 molars. Data from a previous study on the percentage of abutments lacking resistance form for restorations leaving a large dental laboratory was used for comparative statistical tests. RESULTS: Forty-two of the 44 abutments (95%) lacked resistance form. All molar abutments and 93% of premolar abutments lacked resistance form in one or more directions. The one incisor abutment did not lack resistance form. Chi-square test revealed a statistically significant difference in the percentage lacking resistance form between the group composed of clinical failure (uncemented crowns) and the group leaving a dental laboratory with P = .0005 for the molars, and P = .0005 for the premolars. CONCLUSION: The clinical dislodgment of cast restorations is associated with the lack of resistance form in the preparations. In this study, there was a relationship between clinical success or failure and the all-or-none nature of resistance form; dislodged crowns come almost exclusively from preparations with tapers that did not provide resistance form.
UNLABELLED: This study compared the post-operative results of cementing full crowns (all metal or PFM) with either a conventional (Fuji I, GC; n=102) or a resin modified GI luting cement (Rely X, 3M/ESPE; n=107). METHODS: Ten private practitioners fabricated 209 crowns using standardized preparation/luting criteria and randomly assigned cements. Patients self-reported temperature and biting sensitivity, on a 0-10 scale at 24 hours, one week, one month and three months post-cementation. Data were analyzed using t-tests, confirmatory Mann-Whitney tests and Pearson correlations, with a significance level of p < or = 0.05. RESULTS: Of all patients, 50.7% reported any sensitivity at any time period. Mean sensitivity for all patients on the 10-point scale was 0.52 for temperature and 0.23 for biting. Cements did not differ in cold or biting sensitivity at any time. There were many significant (though low) correlations between the sensitivity measures and age (inverse relationship) and dentin area of preparation (direct). The practice-based format provided a viable alternative to performing clinical research.
The ability to create periodontally sound gingival and non-staining or plaque retaining interproximal margins on spacious carious lesions is a daunting challenge in many situations. The case as presented will illustrate the use of a unique matrix system, The Contour Strip from Vivadent, which will encompass the entire outline margins of the upper right lateral incisor of an elderly patient. The age of the patient has no bearing on the use of the technique, but merely reenforces the value of the system in all other situations mimicking a similar restorative obstacle. The use of this custom shaped matrix band, eliminate the free-hand placement and then the laborious creation and finishing of the restoration. LEARNING OBJECTIVES: After reading this paper the reader will understand the manipulation and use of a new labial matrix band which can totally surround the gingival and proximal margins of any anterior and pre-molar teeth. TECHNIQUE CONSIDERATIONS: There are four rules to follow when using adhesive dentistry: Proper preparation of tooth surfaces, both dentin and enamel through mechanical and/or chemical means. Creation of matrix formed molds. Injecting all resins, from the lowest to the highest viscosity. Polymerizing thoroughly through trans-enamel polymerization thus controlling shrinkage.
PURPOSE: The purpose of this study was to compare the emotional effects of tooth loss in three edentulous populations. MATERIALS AND METHODS: A questionnaire study involved 142 edentulous subjects undergoing routine prosthodontic care at Guy's, King's and St Thomas's Dental Institute, London; the Dental School, Dundee, Scotland; and the Faculty of Dentistry, University of Hong Kong. Data were analyzed using the chi-squared test. RESULTS: Difficulty in accepting tooth loss was a relatively common experience (44%) in all groups, with almost half feeling that their confidence had been affected. The majority (66%) felt that their choice of food was restricted and that the overall eating experience was less enjoyable, particularly the Hong Kong group. A significant proportion of the participants were concerned about their appearance without dentures, although the trend was less marked in Hong Kong. Forty-three percent felt that they were not adequately prepared for tooth loss, although the Hong Kong group was least concerned. CONCLUSION: In general, the emotional effect of tooth loss was significant in all groups. The restrictions on daily activities were generally greater in the Hong Kong group. However, this group was much less inhibited by denture wearing. The differences observed in the Hong Kong Chinese are most likely due to different cultural values and expectations associated with these aspects of daily living.
Implant site preparation allows the surgeon to place implant fixtures in the optimum position that is dictated by the final restoration. Armed with procedures to augment implant sites, the surgeon can enhance prosthetic success.
PURPOSE: This article presents a review of the literature on factors that affect the resistance to fracture of post-core reconstructed teeth. MATERIALS AND METHODS: Articles cited in a MEDLINE search were obtained from the journals and reviewed with respect to factors affecting fracture resistance of post-core reconstructed teeth. RESULTS: A large part of the literature reviewed emphasizes the stress distribution during insertion of posts and during function. Other factors, like post length, post diameter, amount of remaining dentin, post material, post adaptability, post design, cement, core material, core and crown design, biocompatibility of post material, use of treated tooth, and load experienced by restored tooth, are also found to influence the fracture resistance of a reconstructed tooth. Of all the factors enumerated, crown design, occlusal forces, and use of the treated tooth are found to have direct impact on the longevity of the restored tooth. CONCLUSION: Literature indicates that (1) preservation of tooth structure is a must; (2) posts should not be used with the intention of reinforcing the tooth; (3) review of functional and parafunctional forces must be undertaken before restoring the tooth, as these will influence the prognosis; and (4) controlled prospective clinical studies evaluating each factor should be undertaken.
Reaction of the pulp to degree-by-degree changes (from 3 to 18 degrees) in inclination of lateral walls of abutment teeth during preparation for cermet dentures was studied by the functional diagnosis methods (electroodontodiagnosis, rheodentography) in 50 patients with intact abutment teeth. Changes in dental pulp electric conductivity and hemodynamics depended on the inclination angle formed during preparation. The optimal safe angle of the lateral wall inclination was determined to be 3-12 degrees. Increase of the angle (> 12 degrees) can lead to traumatic pulpitis.
OBJECTIVE: To investigate the effect on the undergraduate learning process of using an alternative method designed to enhance the visual demonstration of taper on full veneer crown preparations (better understanding of the value of taper on preparations early in the teaching programme in restorative dentistry). DESIGN: A comparison between the conventional teaching of full veneer crown preparations and the same teaching with the additional use of a magnified real time video display using a surgical microscope was investigated in this study. OUTCOME MEASURES: The degree of taper was measured for replica full crown preparations and results compared between different cohorts of undergraduates and experimental conditions. RESULT: Undergraduates taught using the real time video produced more accurately tapered preparations. This ability was retained over one year. CONCLUSIONS: A possible explanation for the result was that the use of magnification improved the undergraduates' precise understanding of taper by enhancing their ability to evaluate this critical measurement during the teaching process.
A case of a traumatized permanent young tooth in which apexification occurred without the benefit of endodontic treatment is reported. It illustrates how a immature incisor that underwent pulp necrosis and periapical inflammation could progress to complete apical formation.
OBJECTIVE: It would be advantageous to be able to use computer-aided design and manufacturing to fabricate a restoration that can be layered with a conventional porcelain veneer in the occlusal region, thus optimizing esthetics, function, and strength. This case study reports the laboratory technique and the clinical performance of 38 partial crowns fabricated with computer technology and veneered with porcelain. METHOD AND MATERIALS: Twenty-one mandibular and 17 maxillary molars in 27 patients were prepared for partial crowns. The occlusal surfaces were lowered (1.5 to 2.0 mm), deep shoulders (1.5 mm) were prepared around the functional cusps, and 1.0-mm-deep shoulders were prepared in the proximal gingival regions. The nonfunctional cusps were prepared with an occlusal shoulder at approximately a right angle with the axial surfaces of the seat. In the computer-aided design procedure, the occlusal table was reduced to 1.4 mm above the preparation surface. The marginal ridge points, the marginal ridge line, the equator line, and the fissure line heights were adjusted accordingly. RESULTS: The lowest occlusal table thickness was 1.1 mm in six partial crowns, 1.2 mm in 26 partial crowns, and 1.3 mm in six partial crowns. The lowest occlusal table thickness of the porcelain veneers varied between 0.4 and 0.6 mm. The total occlusal table thickness thus was 1.5 mm or more. Clinically, no fractures occurred during an observation period varying between 1 and 4 years after placement. CONCLUSION: Computer-aided design and manufacturing technology is also convenient for partial crown preparation design with shoulder finish lines.
Retention of crowns has been shown to be inversely proportional to taper. The objective of this study was to compare the abutment taper of teeth prepared for full veneer crowns by students at the UWI School of Dentistry with those of other dental schools. Twenty five dies were scanned by a Co-ordinate Measuring Machine (CMM) and the mean taper and standard deviations were found to be 20.3 +/- 11.3 degrees mesio-distally and 18.3 +/- 8.5 degrees bucco-lingually. This study shows that the taper achieved by dental students at the UWI School of Dentistry preparing teeth for full veneer crowns is comparable to those achieved by other dental students in the US, UK, Europe and Japan.
The reflex metrograph was used to measure preparation depth for a sample (21) of preparations for porcelain laminate veneers obtained from a large commercial laboratory. Eight (38%) of the teeth investigated were found to be unprepared with 13 (62%) teeth prepared to varying degrees. Five (24%) of the teeth were over prepared with the depth of two preparations exceeding 1.0 mm. There was little evidence that widely advocated guidelines for the preparation of teeth for porcelain laminate veneers had been used. The effect of dentine exposure on the clinical longevity of porcelain laminate veneers remains to be investigated.
OBJECTIVES: The aim of this in vitro study was to evaluate the microleakage in occlusal surfaces, after preparation with Er:YAG laser and compared to the diamond-bur conventional technique. METHODS: Thirty premolars were divided into three groups: I - high-speed handpiece + 37% phosphoric acid; II - Er:YAG laser (350 mJ, 4 Hz and 112 J/cm(2)) + 37% phosphoric acid; and III - Er:YAG laser (350 mJ, 4 Hz and 112 J/cm(2)) + Er:YAG laser (80 mJ, 4 Hz, and 25 mJ/cm(2)). All cavities received the same adhesive system and were restored with flowable composite according to manufacturer's instructions. Teeth were submitted to thermal cycling and immersed in 50% silver nitrate solutions for 8 h in total darkness. Specimens were sectioned longitudinally in the bucco-lingual direction, in slices of 1 mm thick. Each slice was immersed into photo developing solution and was photographed, and microleakage was scored from 0 to 7, by three calibrated examiners. RESULTS: A statistically significant difference (P < 0.0001) was observed between Er:YAG laser prepared and etched specimens and those in the other groups. CONCLUSIONS: It can be concluded that no significant difference was noted between the two types of enamel preparation when etching was performed. Preparing and treating the enamel surface exclusively by Er:YAG laser resulted in the highest degree of leakage.
STATEMENT OF PROBLEM: There is insufficient knowledge of the strength of all-ceramic crowns bonded to natural teeth to warrant the use of all-ceramic crowns in place of metal-ceramic crowns. PURPOSE: The purpose of this study was to evaluate and compare fracture resistance of crowns made of 3 different types of 2 all-ceramic crown systems-0.4-mm and 0.6-mm aluminum oxide coping crowns and zirconia ceramic coping crowns-and metal-ceramic crowns. MATERIAL AND METHODS: Forty intact, noncarious human maxillary central incisors were divided into 4 groups (n=10): Group MCC (control), metal-ceramic crown (JRVT High Noble Alloy); Group AC4, crown with 0.4-mm aluminum oxide coping (Procera AllCeram); Group AC6, crown with 0.6-mm aluminum oxide coping (Procera AllCeram); and Group ZC6, crown with 0.6-mm zirconia ceramic coping (Procera AllZirkon). Teeth were prepared for complete-coverage all-ceramic crowns so that a final dimension of 5.5 +/- 0.5 mm was achieved incisocervically, mesiodistally, and faciolingually. A 1.0-mm deep shoulder finish line was used with a rounded internal line angle. All restorations were treated with bonding agent (Clearfil SE Bond) and luted with phosphate-monomer-modified adhesive cement (Panavia 21). Fracture strength was tested with a universal testing machine at a crosshead speed of 2 mm per minute with an angle of 30 degrees to the long axis of the tooth after restorations were stored in 100% relative humidity of a normal saline solution for 7 days. The mode of fracture was examined visually. Means were calculated and analyzed with 1-way ANOVA and Tukey's HSD (alpha=.05). RESULTS: The means of fracture strength were: Group MCC, 405 +/- 130 N; Group AC4, 447 +/- 123 N; Group AC6, 476 +/- 174 N; and Group ZC6, 381 +/- 166 N. There was no significant difference between groups ( P =.501). The mode of failure for all specimens was fracture of the natural tooth. CONCLUSIONS: There was no significant difference in the fracture strength of the teeth restored with all-ceramic crowns with 0.4- and 0.6-mm aluminum oxide copings, 0.6-mm zirconia ceramic copings, and metal ceramic crowns.
A case report of endodontic treatment of a maxillary lateral incisor that fused with a supernumerary tooth is presented. The fused maxillary lateral incisor was in supraposition on the maxillary dental arch and required orthodontic treatment. The fused tooth was prepared for endodontic therapy. Cleaning and shaping of the root canals were performed. Then, the Ultrafil technique was used for obturation of the root canals. After orthodontic treatment, the teeth was mesiodistally reduced in size and restored with an anterior composite resin.
Fabrication of provisional restorations for teeth prepared to receive porcelain veneers can be a time-consuming and difficult task. This article describes a simple, quick, and predictable procedure to make these restorations. A clinical case is presented to illustrate the technique.