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PubMed2003

[The significance of the size and type of surface of prepared teeth for retention of permanent dentures fixed with zinc-phosphate cement].

The purpose of this paper was to establish, in vitro, the impact of different sizes and prepared teeth roughness on the adhesion strength with cast crowns. Twenty human intact premolars were used in the experiment. They were prepared and divided into two groups depending on the fineness of diamond prepared instrumentation. Sizes of prepared teeth were calculated mathematically, while the dentine roughness was measured by a profile meter. The cast crowns were made by a standard method for each group. The crowns were then cemented with a zinc phosphate cement. After seven days, testing of prepared teeth and cast crowns bonding strength was carried out mechanically in an electronic dynamometer. On the basis of the obtained results the relationship between the size and the accomplished roughness with the obtained values of the retention forces is observed. At the constant convergence angle of the stamp the retention is proportional to the stamp size and the roughness profile.

Chromium Alloys↗
PubMed1998

Adhesive-fixed partial dentures in anterior and posterior areas. Results of an on-going prospective study begun in 1985.

Within the framework of an on-going prospective clinical study begun in 1985, 120 adhesive-fixed partial dentures (AFPD) continued to be examined. The manufacture and the fitting of the AFPDs were carried out following a standard procedure. The preparation technique and the metal framework conditioning (silica-coating, sand-blasting and electrochemical etching) has varied throughout the duration of the study. Using Kaplan-Meier analysis, the survival rate was determined and an analysis of risk with regard to location factors (anterior, posterior; maxilla, mandible), conditioning and preparation techniques (retentive/non-retentive) was determined using the Cox regression model. The location of the AFPD had no influence on the survival rate. The survival time was determined mainly by the preparation technique. Strict preparation of seating grooves and pin holes made a 95% survival rate possible after 10 years (Kaplan-Meier estimation). Without retention, the risk of failure increased by a factor of 3.7.

Adolescent↗
PubMed2004

Microleakage of a pit-and-fissure sealant: effect of air-abrasion compared with classical enamel preparations.

PURPOSE: The aim of this study was to assess the microleakage of a pit-and-fissure sealant after classical enamel preparations (prophylaxis followed by acid etching alone and mechanical widening with bur) and after air abrasion. MATERIALS AND METHODS: Ninety noncarious freshly extracted third molars were randomly assigned to three groups of 30. In each group, the mesial halves of the fissures were treated with air abrasion and conditioned with acid etching for 15 s. In group 1, the distal halves were treated with acid etching alone. In group 2, the distal halves of the fissures were widened mechanically with a bur and etched for 15 s. In group 3, the distal halves were prepared with air abrasion alone. Then the sealant (Clinpro) was applied on the occlusal fissures of all teeth, according to the manufacturer's recommendations. The teeth were thermocycled and the samples placed in a 1% methylene blue dye solution. The teeth showing microleakage and the means of infiltration were assessed with an image analysis system. RESULTS: The microleakage of sealants prepared with air abrasion alone displayed significantly greater microleakage (80%) (p < 0.0001) than the ones placed after prophylaxis and etching (13.33%), bur and etching (20%), or air abrasion and etching (22.2%). The samples prepared with air abrasion alone also showed the highest mean microleakage (1.14 +/- 1.4 mm) when compared to samples receiving prophylaxis and acid etching (0.12 +/- 0.41), bur and acid etching (0.08 +/- 0.26), or air abrasion and acid etching (0.09 +/- 0.4) (p < 0.05). No significant difference was noted between the three types of enamel preparation when etching was performed. CONCLUSION: Air-abrasion treatment does not eliminate the need for etching the enamel surface before applying the sealant.

Acid Etching, Dental↗
PubMed2005

Assessment of sensitivity and specificity of clinical evaluation of cast restoration marginal accuracy compared to stereomicroscopy.

STATEMENT OF PROBLEM: One of the most important criteria for the clinical acceptability and longevity of cast restorations is marginal adaptation. However, there is limited information on the accuracy of commonly practiced evaluation techniques. PURPOSE: This study assessed the effect of preparation design on marginal adaptation. In addition, sensitivity and specificity of clinical evaluations of marginal adaptations of cast restorations were assessed and compared to stereomicroscopy. MATERIAL AND METHODS: Three Ivorine molar teeth of differing designs were prepared: (1) a complete crown preparation with a chamfer finish line, (2) a complete crown preparation with a buccal shoulder and beveled finish line, and (3) a three-quarter crown preparation with proximal boxes and beveled finish line. Twenty-four castings (n = 8) were prepared (Ney technique casting metal). Twelve circumferential sites were identified for examination on each casting using a stereomicroscope, which was interpreted using software (Bioquant 98). The clinical examinations included explorer examination to detect marginal gap by tactile feel, followed by examination with a disclosing media (GC FitChecker). Chi-square tests of independence were used to evaluate the effect of preparation design and compare agreement between examination methods for detection of marginal gap size of greater than or equal to 30 microm (alpha=.05). RESULTS: The overall marginal adaptation of preparation designs was not significantly different. Results of explorer examination at 30-microm sensitivity and specificity were 46% and 97%, respectively. Similar values for disclosing media at 30 microm were 12% sensitivity and 97% specificity. The overall percent agreement with the stereomicroscope using the explorer was 58.3%, with 23.6% correct acceptance rate and 34.7% correct rejection rate. With respect to detection of marginal fit, the combination of disclosing material with explorer data did not yield significantly improved results (59.4%), as compared to explorer alone. A receiver operator characteristic curve yielded satisfactory sensitivity (0.8) and specificity (0.9) at a gap size value of 124 microm. CONCLUSION: Within the limitations of this study, the preparation design did not significantly affect the marginal adaptation. Clinical detection, with similar sensitivity and specificity as the stereomicroscope, occurred at marginal openings greater than or equal to 124 microm. Therefore, commonly used clinical evaluation techniques using an explorer and disclosing media may be inadequate for assessments of marginal accuracy.

Chi-Square Distribution↗
PubMed2003

The single-unit crown: factors for clinical success.

Application of the crown preparation guidelines obtained through theoretical models, laboratory testing and clinical studies provide an evidence-based rationale for clinical practice procedures. The evidence-based rationale has been presented to support basic day-to-day techniques in clinical practice. As new techniques and materials are developed, each should be evaluated carefully prior to clinical use and acceptance.

Crowns↗
PubMed2006

Retrieval of amalgam from the root canal space.

Removal of foreign objects from the root canal can be very frustrating. The use of a variety of instruments and techniques has been suggested for the retrieval of obstacles from root canals during endodontic treatment. This article describes a method for retrieving a large mass of amalgam restoration that was wedged into the root canal. The amalgam, which had served as the provisional restorative material during apexification of an immature ante rior tooth, was inadvertently pushed into the root canal. After the mass was bypassed, the amalgam was loosened with the aid of copious irrigation, chelation, and flotation. Hedstrom files twisted around the object allowed sufficient grip for its retrieval, enabling completion of the root canal treatment.

Calcium Compounds↗
PubMed2004

Assessing the reliability of a digital preparation assistant system used in dental education.

Use of a digital preparation assistant system may improve considerably the quality of preclinical dental education, provided the system works reliably. Thus, the purpose of this pilot study was to quantitatively assess the reliability of a new preclinical digital preparation assistant system (PREPassist, KaVo, Germany). The system was used to repeatedly scan four different unprepared and four different prepared teeth both with and without repositioning. Corresponding measurements were made to quantify accuracy, repeatability, and reproducibility. This was done by estimating the measurement error. Based on this estimation, respective limits of agreement were calculated. We used these ranges, along with assessments of the measurement's accuracy, to judge whether the results satisfy our expectations for clinically acceptable measurements. For preclinical laboratory instruction, the results indicate an acceptable accuracy (mean accuracy of 89 microm) of the measurements. This assessment applies as well to repeatability, given by the range of the respective limits of agreement (range <200 microm). However, in the case of reproducibility, the limits revealed discrepancies of practical importance (range >200 microm). Reproducibility of tooth repositioning in the available mounting device is unacceptable for preclinical laboratory instruction because of the observed range >200 microm. Thus, there is a need for the manufacture of new and more reliable mounting devices because reproducibility procedures are mostly encountered in preclinical instruction in restorative techniques. In contrast to reproducibility, accuracy and repeatability are acceptable for practical purposes. Balancing advantages and disadvantages, we conclude that, in general, the PREPassist system delivers reliable results.

Computer Simulation↗
PubMed2006

A comparison between in vivo radiographic working length determination and measurement after extraction.

The purpose of this study was to compare the difference between the in vivo working length established by viewing a periapical radiograph and the in vitro measurement from the file tip to the apical foramen of the extracted tooth. Twenty-six canals from teeth that had been treatment planned for extraction were accessed under rubber dam isolation. The coronal portion of each canal was flared using Gates Glidden drills, and a K-type file was inserted down the canal until an electronic apex locator indicated that the file had reached the apex. A size 20 K-type file was locked into place with glass ionomer cement at this position. A radiograph was exposed and the tooth was extracted. Each tooth was viewed using a videomicroscope at 30x original magnification, and the distance from the file tip to the most coronal aspect of the major foramen was measured. Six examiners viewed each radiograph and assessed the working length of each canal. Chi(2) analysis of the data revealed a significant difference (p < 0.01) between the estimation of working lengths and the microscopic measurements. The examiners overestimated the distance between the file tip and the apical foramen of the tooth when the file was placed short, and underestimated the distance when the file was placed long. In conclusion, when the file is short it is actually closer to the apical foramen than it appears radiographically; when it is long it is actually longer than it appears radiographically.

Adolescent↗
PubMed2003

Composite indirect-direct method for fabricating multiple-unit provisional restorations.

This article describes a method for fabricating multiple-unit provisional restorations by use of the indirect-direct method without the need for abutment preparation on diagnostic casts. Composite is used with fiber reinforcement to create a provisional shell in a vinyl polysiloxane matrix. This method reduces chair time, as well as laboratory time required to fabricate provisional restorations. Control of restoration contours and incisal edge position is also enhanced.

Bisphenol A-Glycidyl Methacrylate↗
PubMedDate not supplied

Effect of measurement site on the dimensional accuracy of die-forming materials and techniques.

To date, the comparisons of dimensional accuracy of various die materials has been investigated primarily by using a one-dimensional measurement on one die. However, a single measurement may not adequately represent the complex preparations that are encountered frequently in clinical dentistry. This investigation utilized a standardized model with two identical dies to measure die accuracy at four sites, using five different die-forming materials/techniques.

Analysis of Variance↗
PubMed2002

[Effect of selective polishing of teeth on local circulation in prosthetic treatment by implantation].

An effect of occlusion disorders on a regional circulation was studied in periodontal tissues of abutment teeth, antagonist teeth, periimplant zone at different stages of preparation for a prosthesis by normalization of occlusion ratios by means of selective polishing of teeth. The terms and the periodicity of selective polishing promoting redistribution of the masticating pressure were determined. The connection of these factors was examined with periodontal vessel tonicity and periimplant zone on the basis of the rheoparodontographic findings.

Dental Abutments↗
PubMed2002

Crowns and other extra-coronal restorations: cores for teeth with vital pulps.

Cores for teeth with vital pulps is the seventh in the series of crowns and other extra-coronal restorations. A core is defined as 'that part of a preparation for an indirect restoration consisting of restorative material'. This article questions the need for routine pin placement and addresses the following issues--removal of existing restorations, the need for a core, core materials, core retention, and problem solving.

Composite Resins↗
PubMed2005

Risk factors for failure of glass fiber-reinforced composite post restorations: a prospective observational clinical study.

Glass fiber-reinforced endodontic posts are considered to have favorable mechanical properties for the reconstruction of endodontically treated teeth. The aim of the present investigation was to evaluate the survival of two tapered and one parallel-sided glass fiber-reinforced endodontic post systems in teeth with different stages of hard tissue loss and to identify risk factors for restoration failure. One-hundred and forty-nine glass fiber-reinforced endodontic posts in 122 patients were followed-up for 5-56 months [mean +/- standard deviation (SD): 39 +/- 11 months]. Glass fiber-reinforced endodontic posts were adhesively luted and the core was built with a composite resin. Cox proportional hazards models were used to evaluate the association of clinical variables and failure rate. Higher failure rates were found for restorations of anterior teeth compared with posterior teeth [Hazard-Ratios (HR): 3.1; 95% confidence interval (CI): 1.3-7.4], for restorations in teeth with no proximal contacts compared with at least one proximal contact (HR: 3.0; 95% CI: 1.0-9.0), and for teeth restored with single crowns compared with fixed bridges (HR: 4.3; 95% CI: 1.1-16.2). Tooth type, type of final restoration and the presence of adjacent teeth were found to be significant predictors of failure rates in endodontically treated teeth restored with glass fiber-reinforced endodontic posts.

Adolescent↗
PubMed2006

A new design for all-ceramic inlay-retained fixed partial dentures: a report of 2 cases.

In a previous clinical study, all-ceramic resin-bonded 3-unit inlay-retained fixed partial dentures (IRFPDs) had a significantly worse outcome in the posterior region than did crown-retained 3-unit FPDs made from the same material. Debonding or fractures were causes of failure. To improve the clinical outcome of IRFPDs, a new framework design was developed: (1) The inlay retainers were made out of CAD/CAM-manufactured zirconia ceramic to improve fracture resistance, and additional veneering of the inlays was omitted. (2) The inlay retainers were completed with a shallow occlusal inlay (1-mm minimum thickness) and an oral retainer wing (0.6-mm minimum thickness). The wings were designed to reduce stress on the inlay retainer caused by torsion forces when the FPD is loaded nonaxially and to increase the enamel adhesive surface area. The pontic was circumferentially veneered with feldspathic porcelain. The clinical and laboratory procedures of this new treatment modality are described, and 2 exemplary clinical cases are presented. This new preparation and framework design might improve the clinical outcome of all-ceramic resin-bonded IRFPDs. However, adequate evidence of long-term safety and efficacy is required before this new design can be recommended for general clinical practice.

Adult↗
PubMed2002

The era of high speed development in dentistry.

The development of the high-speed handpiece is a story of fast-moving change. Few of today's practicing dentists worked during the days in which use of low-speed, belt-driven handpieces was the norm for cavity preparation and there were no high-speed drills. During the decade of the 1950s, sweeping changes came about with the introduction of the high-speed handpiece and the associated promulgation of air abrasion and ultrasonic methods for cavity preparation. Researchers and developers from New Zealand, Sweden and the United States played parts in this chronology of events. Dental practitioners have used the high-speed handpiece for over forty years and, although laser technology has been introduced and air abrasion has been re-introduced, there is no prospect of replacement of the high-speed handpiece in the foreseeable future.

Dental High-Speed Equipment↗
PubMed1999

A 4-year clinical study on amalgam, resin composite and resin-modified glass ionomer cement restorations in overdenture abutments.

OBJECTIVE: To assess the performance of three different filling materials in overdenture abutment teeth. METHODS: In 49 patients amalgam, resin composite and resin-modified glass ionomer cement were used to seal the root canal orifices of 155 overdenture abutment teeth. After initial preparation of the cavities, the three restorative materials were randomly assigned to the abutment teeth using a number of balancing criteria. All patients were reviewed every six months and received the same preventive regimen. Survival was assessed at two levels: Sorig (survival of the restoration independent from eventual maintenance treatments) and Scomp (restorations survived even without maintenance treatments). RESULTS: The calculated overall survival percentage of the original restorations (Sorig) after four years was 63 +/- 6% (mean +/- SE). Calculation for the overall complete survival (Scomp) revealed a percentage survival of 57 +/- 6%. At both levels, the differences between the survivals of the investigated materials were not statistically significant (p-values > 0.05). Two abutments were lost, severe caries was the reason for one extraction and another abutment tooth was extracted for periodontal reasons. CONCLUSIONS: The results of this study did not point out a superior restorative material for the seal of root canal orifices of overdenture abutments. The distribution of failures over the patients indicates a certain patient dependency.

Composite Resins↗
PubMedDate not supplied

Subcutaneous cervicofacial emphysema and pneumo-mediastinum: a rare complication after a crown preparation.

Subcutaneous cervicofacial emphysema and pneumo-mediastinum are relatively rare complications from different dental procedures (including oral surgery and restorative treatment). Many cases go unrecognized or are misdiagnosed. While the majority of cases resolve spontaneously, some can lead to life-threatening complications that require emergency intervention. This article presents a case report of subcutaneous and mediastinal emphysema following a routine restorative dental procedure. The differential diagnosis and management of this condition is discussed.

Adult↗
PubMed2004

The use of sectional impressions and a transfer index for extensive fixed prosthodontic treatment.

The philosophy of positioning the margins of crowns supragingivally may not be applicable with the presence of caries, erosion, abfraction (noncarious cervical lesion), short clinical crown length, or esthetic concerns. In such situations, it is essential not only to record precise subgingival details of all of the prepared teeth but also to accurately transfer them to a working master cast. If a patient presents with oral and/or gingival conditions that compromise the clinician's ability to obtain a single full-arch impression for extensive fixed restorations, a technique using sectional impressions, an intraoral transfer index, and a transfer impression for transfer dies will play a vital role in the patient's treatment.

Crowns↗