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PubMed2001

The unpredictability of seal after post space preparation: a fluid transport study.

A root canal filling remaining after post space preparation is commonly expected to provide adequate seal. Coronal leakage of 30 endodontically treated teeth was measured before post space preparation using a fluid transport assay. In 10 of these teeth post space was prepared, using a two-step procedure, first to a remaining filling of 6 mm and then to 3 mm, with the leakage studied after each step. In 10 teeth the removal was done in one step to a remaining length of 3 mm. The other 10 teeth, with intact root canal fillings, served as controls and were tested twice for leakage. A significant difference was found between the sealing ability of intact fillings and that of partially removed ones (p < 0.05). The difference between the sealing ability of 3 and 6 mm remaining length group was not statistically significant. The lack of statistical differences between the 6 mm and 3 mm fillings was due to a great variability which existed among the 3 mm remaining fillings. These results suggest that 3 to 6 mm fillings provided a seal inferior to that of intact root canal fillings. Reduction of the fillings to 3 mm resulted in an unpredictable seal.

Analysis of Variance↗
PubMed2002

Effect of dowel space preparation and composite cement thickness on retention of a prefabricated dowel.

PURPOSE: This investigation examined what effect cement thickness had on retention of prefabricated endodontic dowels luted with a composite resin cement (Panavia 21 OP; J Morita, Irvine, CA) into canals previously obturated with gutta percha and a eugenol-based sealer. MATERIALS AND METHODS: Sixty-four single-rooted teeth were decoronated, filed, cleaned, and sequentially shaped with sizes 2-5 Gates Glidden drills (Dentsply/Maillefer, Tulsa, OK) and 0.12 taper rotary instrumentation. Teeth were then divided into 4 groups of 16 specimens each. All specimens were obturated with gutta percha and a eugenol-based sealer. Dowel space preparation and dowel cementation were completed 1 week after obturation. Ten-millimeter-deep dowel spaces were prepared using dowel drills with 4 different diameters: size 5 Parapost drill (Group 1; Coltene/Whaledent, Mahwah, NJ); size 5.5 Parapost drill (Group 2; Coltene/Whaledent); size 6 Gates Glidden drill (Group 3; Dentsply/Maillefer); size 6 Parapost drill (Group 4; Coltene/Whaledent). Size 5 Paraposts were then cemented with Panavia 21 OP. After 48 hours of storage, specimens were mounted in polyvinyl chloride (PVC) pipe with acrylic, and the dowels were removed in tensile mode using a universal testing machine at 1 mm/min, with data recorded in kilograms. RESULTS: (all values in kilograms) Group 1 (Parapost 5) mean = 15.07, 95% confidence interval (CI) = +/-6.11; Group 2 (Parapost 5.5) mean = 25.60, 95% CI = +/-7.39; Group 3 (Gates-Glidden 6) mean = 43.15, 95% CI = +/-7.81; Group 4 (Parapost 6) mean = 37.75, 95% CI = +/-6.35. Analysis of variance and Bonferroni tests revealed that Group 3 had significantly greater mean retention strength values than Group 1 and Group 2 (p <.05), and that Group 4 had significantly greater mean retention strength values than Group 1 (p <.05). CONCLUSIONS: Paraposts cemented with Panavia 21 OP showed significantly greater retention in oversized dowel spaces compared with dowel spaces prepared with the manufacturers' matched dowel-drill set.

Analysis of Variance↗
PubMed1997

Effect of two etching times on the sealing ability of Clearfil Liner Bond 2 in Class V restorations.

PURPOSE: To investigate the sealing ability of the Clearfil Liner Bond 2 self-etching primer in Class V restorations placed under clinical and laboratory conditions. MATERIALS AND METHODS: Firstly, the influence of two etching times of the self-etching primer were tested in vitro. In 10 Class V cavities (Group 1), the self-etching primer was applied for 30 seconds on the enamel and dentin, while in another 10 Class V cavities (Group 2) the etching time was 60 seconds. Since the Group 2 samples showed the best in vitro sealing ability at both the enamel and cementum-dentin sites, the teeth of Group 3 (10 restorations) were restored as in Group 2 under clinical conditions, applying the self-etching primer for 60 seconds. The sample teeth were extracted after 65-90 days, and then processed for leakage. Two other groups of 10 samples each were prepared under laboratory conditions to investigate hybrid layer, resin tags and adhesive lateral branch formation. A flat buccal surface on each extracted tooth was prepared. Group 4 samples were conditioned for 30 seconds, and those of Group 5 for 60 seconds. RESULTS: In Group 1, 40% of the restorations showed leakage at the cementum-dentin site and 40% at the enamel site. Groups 2 and 3 showed statistically significant difference (less leakage) than Group 1. In Group 2 and 3 no leakage was found at the enamel site, and only a moderate leakage (10% and 20% of restorations, respectively) was found at the cementum-dentin site. The scanning electron microscopy observations of Group 4 samples showed a thin hybrid layer, with well-fitting and smooth resin tags and adhesive lateral branches only sporadically. Group 5 samples presented a thicker hybrid layer, rough and deep resin tags with many adhesive lateral branches. The etch enamel pattern was more uniform and rougher in Group 5 than in Group 4. The 60-second application time of the self-etching primer seems to be more reliable than a shorter conditioning time in day-to-day practice.

Acid Etching, Dental↗
PubMed1995

The effect of magnification on the performance of fixed prosthodontic procedures.

This study attempts to quantify the effect of magnifiers on the quality of typical procedures in fixed prosthodontics that are technique-sensitive and have significant increase in clinical success when errors are minimized. Dental students who performed fixed prosthodontic procedures while using magnifiers were found to have committed half as many errors as students who performed the same preparation without the aid of a magnifier.

Dental Equipment↗
PubMed2000

[Estimation of age from teeth using the racemization of aspartic acid (racemization method)].

We report a method for estimation of age from teeth using the racemization of amino acids (racemization method). This method is based on the characteristics of the constant age-related increase in the amount of D-aspartic acid in dentin. We estimated age by measuring the ratio of D-aspartic acid to L-aspartic acid, i.e. the ratio of racemization ¿ratio of D/L, ln[(1 + D/L)/(1 - D/L)]¿. Because different D/L ratios have been obtained from different teeth in the same individuals and from different sites of dentin in the same tooth, we usually prepare bucco-lingual longitudinal sections at the central part of each tooth, and prepare samples of powdered whole dentin. This powder is then mixed and used to measure the D/L ratio in the dentin. To accurately estimate age from forensic specimens, we simultaneously measured the D/L ratios in more than four control teeth of the same type obtained from subjects of known age. Use of control teeth is necessary because it is sometimes difficult to maintain constant running conditions for gas chromatography to obtain reproducible values in different runs. Therefore, for every measurement, we determined an equation for calculating age from the D/L ratios of control teeth, and estimated the age of the specimen tooth by substituting in its D/L ratio. The most reliable results were obtained using samples of lower incisors or premolars, which are single-rooted teeth with a relatively small volume of dentin. Thus sampling of the dentin is easier than for other teeth. It is better to keep control teeth desiccated because racemization does not proceed readily under such conditions. The deviation from the actual age in the cases we examined was less than 3 years. Thus, racemization of amino acids can be used for accurate estimation of age from teeth.

Adolescent↗
PubMed2002

Preparation of composite retentive areas for removable partial denture retainers.

A method is presented in which light-polymerized composite material is used to obtain retention for a removable partial denture when usable natural tooth undercuts are unavailable. The desired contour is waxed on a diagnostic cast with the use of a surveyor, captured in a light-polymerizing temporary restorative material, and reproduced in composite resin on the abutment teeth.

Composite Resins↗
PubMed1996

[Preparation forms and filling techniques for posterior composite restorations].

The operator is a very important factor in achieving high quality posterior composite resin restorations. Specific clinical procedures are required to obtain a clinical successful restoration. Tooth saving preparations are made when primary caries is treated. However, tunnel preparations have major disadvantages. The application of a liner or base under a composite restoration is not required anymore since it does not improve the marginal seal when using an total-etch adhesive. The handling and application of the composite should be done with an injection technique and in layers, whereas low viscous composites are giving the best results in preventing voids.

Composite Resins↗
PubMed1992

The effect of thermocycling in microleakage analysis.

The purpose of this study was to evaluate the effect of thermocycling on dye penetration during in vitro microleakage analysis of composites. Fifty non-carious human molars, stored in 75% ethanol, were divided into five groups (N = 10). Each tooth was prepared for a MOD slot preparation using a high speed handpiece and water, one proximal cervical margin in cementum, the other in enamel. The enamel margins were etched, rinsed, dried, and the composite inserted and cured in multiple increments. Group A was not thermocycled (TC) and was immersed in 0.5% basic fuchsin dye for 24 h at 37 degrees +/- 1 degrees C. Group A' was not TC and was immersed in 0.5% basic fuchsin dye for 4 h at 37 degrees +/- 1 degree C. Group B was TC in a water bath and immersed in dye as with Group A, Group B' was TC and immersed in dye as in Group A'. Group C was TC, as in Group B, but in a basic fuchsin dye bath. Thermocycling consisted of 250 cycles, 15 s dwell time each in 5 degrees C and 50 degrees C bath. The teeth were mounted in acrylic, and multiple cross-sections of all surfaces were prepared. Dye penetration was read on a scale of 0 (no leakage) to 4 (leakage to the pulpal floor) and means calculated for each surface and tooth. There was no significant increase of microleakage in restorations when thermocycling was used to simulate temperature extremes, either in dye or water baths, as opposed to restorations which were not thermocycled.

Composite Resins↗
PubMed1998

Evaluation of the clinical performance and effectiveness of adhesively-bonded metal crowns on damaged canine teeth of working dogs over a two- to 52-month period.

In this clinical study, 41 metal full crown restorations of canine teeth were placed in 18 working dogs. Twenty-six canine teeth had severe attrition with no involvement of the pulp cavities; 15 fractured canine teeth were endodontically treated. With the exception of one tooth, at least one-third of the coronal part of each canine tooth was available for a supragingivally performed, minimal tooth crown preparation. A dental resin luting cement technique was used to bond the electrolytically etched crown (made from an alloy of cobalt-chrome-molybdenum) to the tooth. The metal crowns were slightly shorter and with a more rounded tip than the original tooth. Posts or post-and-core techniques were not used. Median follow-up period was 30 months (range 2 to 61 months), at which time 36 crowns were found to be intact and functional. Five crowns were lost; three as a result of subsequent injury and fracture of the tooth below the crown; one as a result of use of less than one-third of the coronal portion of the tooth for retention of the crown; and one as a result of an oblique fracture of the root.

Animals↗
PubMed1998

Adhesive crowns and fixed partial dentures fabricated of ceromer/FRC: clinical and laboratory procedures.

Ceramic optimized polymer and fiber-reinforced composite materials represent a significant development in prosthetic dentistry. When utilized in conjunction with adhesive luting techniques, exceptionally conservative crown and bridge restorations may be achieved. This article discusses utilization of these materials in inlay and onlay restorations, as well as clinical and laboratory procedures for fabrication, preparation, and seating of adhesive crown and bridge restorations. The initial results of restorations utilizing these innovative materials are presented.

Ceramics↗
PubMed2001

Root canal treatment in an unusual maxillary first molar: a case report.

AIM: The aim of this clinical article is to describe the unusual anatomy that was detected in a maxillary first molar during routine endodontic treatment. SUMMARY: Success in root canal treatment is achieved after thorough cleaning and shaping followed by the complete obturation of the root canal system. Such treatment may be performed in root canal systems that do not comply with the normal anatomical features described in standard textbooks. The present case describes root canal treatment in a maxillary first molar with two roots and a type IV canal configuration in the buccal root. KEY LEARNING POINTS Careful examination of radiographs and the internal anatomy of teeth is essential. Root canal treatment is likely to fail if the entire system is not debrided and filled. Anatomic variations can occur in any tooth.

Dental Pulp Cavity↗
PubMed2000

Compressive shear strength of core materials and restoring techniques.

In this study, ninety extracted endodontically treated mandibular molars were mounted in acrylic resin blocks. Five groups of eighteen extracted teeth were prepared by two different techniques. A peripheral shelf 2 mm deep and 1.4 mm wide was prepared as a first technique, while TMS pins were used in the second group. The teeth were then restored with five different core materials: silver-reinforced glass-ionomer, resin-modified glass-ionomer, self-cured glass-ionomer, polyacid-modified composite resin, and titanium-reinforced composite resin. An Instron testing machine was used to apply shear force at a crosshead speed of 2 mm/min until fracture occurred. The results were obtained statistically using analysis of variance and least significant difference tests. According to the results of this study, Ti-core and composite resin were the strongest core materials when subjected to shear forces, and the most retentive preparation design was the vertical-pin design. The fractures of these materials with a vertical-pin design were mostly seen at the core and the tooth.

Analysis of Variance↗
PubMed2004

Clinical response to a vacant post space.

AIM: To report a case demonstrating a radiolucency of developing adjacent to an unfilled post space. SUMMARY: A mandibular left first molar was root filled before post-space preparation. The tooth was restored coronally but the post space was left empty, and 14 months later, pain and furcal radiolucency developed. Cleaning, shaping, medicating and filling the post space resulted in the resolution of symptoms and healing of the radiolucency. KEY LEARNING POINTS: Post space should be prepared under conditions of asepsis. A post space must not be allowed to remain empty when a tooth is restored.

Adult↗
PubMed1997

Indirect posterior restorations: steps to clinical success.

Continued advances in adhesive dentistry allow predictable bonding of tooth-supporting restorations using conservative preparation. As tooth-colored restorative materials continually yield improved durability and esthetic properties, treatment options expand. There has been slow acceptance of both direct and indirect posterior esthetics. The focus of this article is to review clinically proven techniques that when followed will consistently result in long-term functional indirect restorations.

Bicuspid↗
PubMed1996

Polylactic acid (PLA) root replica in ridge maintenance after loss of a vertically fractured incisor.

A periodontally affected tooth was prepared for a special treatment: Calcium hydroxide was introduced into the apical half of the root canal whereas its cervical part was filled with glass ionomer cement. The tooth was shortened subgingivally. After 6 weeks of epithelization over the residual root a palatal full-thickness flap was mobilized. The root was carefully extracted and chairside copy-milled from the biodegradable polylactic acid (PLA) material. The PLA-replica was implanted immediately into the socket and the flap was sutured. Aim of the treatment was to prevent the ridge collapse of the extraction area. Ridge height could be preserved during the 21 months of observation. With time the radiographic density of the cancellous bone increased in the implanted area, indicating that a PLA-replica is replaced by host's bone tissue.

Adult↗