Predictors of oral health after spinal cord injury.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To examine predictors of oral health in people with spinal cord injury (SCI). METHODS: Ninety-two people with SCI (> or =6 months, 44% cervical level) completed questionnaires and underwent oral examination. Socio-economic, injury-related and oral habits variables were used for predicting oral health score (OHS); Decayed, missing and filled teeth (DMFT) score; and periodontal screen and recording index (PSR). RESULTS: Most people with SCI were able to bring at least one hand to the mouth (82%) and brush teeth independently (65%). Regarding daily oral habits, 84% reported brushing teeth, 48% rinsing mouth, 14% flossing, 33% tobacco use and 13% mouthstick use. Only 32% had teeth cleaned within the past year. Oral examination revealed three decayed and eight missing teeth on average, with prominent periodontal disease (64%). Employment before SCI and more risky oral habits were significant predictors of worse OHS (P=0.005 and P=0.014, respectively) and PSR score (P=0.010 and P=0.035, respectively). Older age was the only predictor of worse DMFT score (P<0.001). CONCLUSION: Oral health appears compromised in people with SCI. Identification of modifiable risk factors warrants examination whether intervention with focus on behavioral changes may improve oral health in this population.

Dimensional accuracy of improved dental stone and epoxy resin die materials. Part II: Complete arch form.

STATEMENT OF PROBLEM: Little information has been reported with regard to the dimensional accuracy of improved dental stone materials for reproduction of an entire arch form. PURPOSE: The purpose of this study was to evaluate the ability of an epoxy resin die material and a type IV dental stone to dimensionally reproduce an entire arch form. MATERIAL AND METHODS: Models were fabricated and measurements were made of reference marks to calculate dimensions from first molar to the midline bilaterally and between first molars. Each measurement was repeated three times and the mean measurement and percent relative change was calculated for each dimension. RESULTS: The results revealed that the difference in the relative change in two dimensions was statistically significant for the epoxy resin group (p < 0.05). CONCLUSIONS: The materials provided a similar degree of dimensional accuracy in reproducing a complete arch when used with addition silicone impression material.

Dimensional accuracy of improved dental stone and epoxy resin die materials. Part I: Single die.

STATEMENT OF PROBLEM: Improved dental stone has been widely used for producing dies for the fabrication of restorations with the lost-wax technique. Improved dental stone is used for several reasons, but it is selected most often because of its reasonable cost, ease of use, and ability to produce consistent results. PURPOSE: This study evaluated the ability of an epoxy resin die material and a type IV dental stone to dimensionally reproduce a custom-fabricated metal die. MATERIAL AND METHODS: Dies were fabricated and measurements were made from three reference lines. Measurements were repeated three times for the master die and for the specimen dies. A mean measurement and percent relative change for each dimension was calculated. RESULTS: A significant difference in the relative change for die height was found between the groups studied (p < 0.003). CONCLUSIONS: This epoxy die system will provide a degree of dimensional accuracy comparable to gypsum when used with addition silicone impression material.

Vital bleaching for aesthetic improvement.

Vital bleaching is one of the least invasive, most conservative, and most cost-effective procedures to dramatically improve the aesthetic appearance of a patient's smile and self-confidence. Bleaching began as an in-office procedure and required multiple visits. With the arrival of dentist-monitored at-home procedures, bleaching has become widely known and used. This presentation evaluates the advantages of the higher viscosity adhesive formulation bleaching materials, which prevent dehydration and reduce the subsequent color change upon rehydration.

Procedural hemostasis and sulcular fluid control: a prerequisite in modern dentistry.

As dental technology advances, clinicians are presented with a variety of new materials and application techniques for the restorative procedures. The learning objective of this article is to provide a sequential approach to the management of soft tissues and adhesive dentistry adjacent to the gingival tissues. Hemostasis and control of sulcular fluids are discussed as prerequisites for precise fitting and sealing of margins adjacent to gingival tissues. The utilization of a knitted displacement cord is introduced. The technique of applying hemostatic solution is presented for the clinician with a description of materials and application procedures.

Post-and-core assemblies made with an accelerated pattern elimination technique.

PURPOSE: Accelerated pattern elimination has the potential for increasing productivity. This study evaluated the accelerated pattern elimination technique using three commonly used phosphate-bonded investments. MATERIALS AND METHODS: Part one of this study determined the mean time interval from start of mixing to the maximum exothermic setting reaction temperature for each investment. A chromel/alumel thermocouple was placed at the heat center of a methylcellulose lined casting ring, using wet or dry ring liner. Investments were vacuum mixed at the recommended ratio for the accelerated technique. Colloidal silica solution and ddH2O were combined at a 50:50 ratio to meet the manufacturer's recommended liquid volume. Part two determined the dimensional reproduction of a standardized pattern and its casting using both casting techniques. Mixing ratios were the same as in part one for the accelerated technique and 75% colloidal silica to 25% double-distilled water (ddH2O) for the conventional technique. The accelerated technique used the mean setting time established in part one followed by a 15-minute furnace holding time at 725 degrees C (1350 degrees F). The conventional technique used a 1-hour bench setting time, followed by placing the mold into a cold furnace. A controlled rate of climb to a maximum temperature of 725 degrees C (1350 degrees F) was used with a 1-hour soak time. Each pattern and its casting were measured at four sites: (1) Length of the post-and-core assembly, (2) maximum core diameter, (3) post diameter at the core base, and (4) post diameter at its apex. RESULTS: A significant difference was found between the time interval to maximum exothermic setting reaction temperature for all the investments (P < .01). The accelerated technique produced castings with a relative dimensional increase of 0.11% to 4.80%. The conventional technique ranged from a 0.04% decrease in size to an increase of 3.65%. Castings made with the accelerated technique were significantly different than those made with the conventional technique (P < .01). CONCLUSIONS: Differences in the time interval to maximum exothermic setting reaction temperature indicate that each phosphate investment should have a recommended setting time before introduction into the furnace. The carbon-containing investment showed the least relative change of the three investments evaluated for both casting techniques.

Microhardness evaluation of a two-piece post and core technique.

This study compared the microhardness of one- and two-piece cast post cores. Twenty 0.070 inch Whaledent "burn-out" posts were invested in a phosphate investment, cast, and bench cooled to room temperature. Five samples, were grouped by Sturdicast or Midas metal and by casting technique. The specimens were cast in matched pairs with one of each technique per casting ring. The Vickers hardness number sites were centered on the post diameter with the core-to-post head junction used as a baseline, at the following sites: (1) 1.5 mm into the core to post head assembly; (2) at the junction of the post to the post head and core assembly; (3) 1 mm into the post; (4) 2 mm into the post; and (5) 3 mm into the post. There were no significant differences in microhardness at the sites tested for metal or casting technic (p < 0.05). This indicated that a two-piece post and core has similar hardness values to the one-piece casting.

The retention of amalgam and composite resin by a smooth, reverse-tapered pin.

In this study, the retention of composite resin and amalgam by a smooth, reverse-tapered pin was compared to that of threaded pins. The smooth pin was significantly lower in retention than the threaded pins for each material, and caused a greater frequency of failure of the restorative material than the threaded pins. The newer smooth pin is probably not an improvement over the conventional threaded design.

Margin configuration, die spacers, fitting of retainers/crowns, and soldering.

This article focuses on different margin configurations and the criteria they must meet to be considered clinically successful. In addition, the use of die spacers to lessen the cement film thickness to achieve a better marginal adaptation of cast restorations is presented. Also, the article presents a step by step method for fitting crowns or retainers in the laboratory and in a clinical setting to make this important procedure less time consuming, more precise, and easy to finalize. Finally, soldering in dentistry and the criteria required for its successful execution are discussed.

Retention design for amalgam restorations: pins versus slots.

The use of pins or slots to provide retention for amalgam restorations has been shown to be equally effective by some authors whereas the pin method has been shown to be more effective by others. This study was done to determine whether the different methods would be affected by the outline form of the preparation. One hundred forty melamine teeth were prepared in three outline forms determined by the cusp that was removed: (1) mesiopalatal, (2) mesiopalatal and distobuccal, and (3) mesiopalatal, distobuccal, and mesiobuccal cusps. Each outline form was restored with a uniform volume of hand-condensed amalgam with pin or slot retention and milled to an occlusal angle of 30 degrees. A load was placed on the milled occlusion with a stainless steel ball to the point of fracture with an MTS machine. No significant difference was found between the pin or slot design for the outline forms evaluated.

Threaded acetabular components for primary and revision total hip arthroplasty.

A clinical and radiographic review of 48 total hip arthroplasty patients with threaded acetabular components was undertaken at 24-44 months of follow-up study. Twenty-five patients had primary hip arthroplasties and 23 had revision procedures. Clinical scores revealed good to excellent results in 60% of primary and 30% of revision procedures. Radiographic analysis revealed stable acetabular components in 88% of primary and 61% of revision procedures. Potentially loose acetabular components were noted in 8% of primary and 4.3% of revision procedures and loose acetabular components in 4% of primary and 34.7% of revision procedures. The rate of acetabular component loosening was considered unacceptably high in revision cases and an area of concern in primary cases. Discretionary use of these components is advised.

Evaluation of a two-piece post and core fabrication technique.

Casting a core to a prefit post reduces the need for adjustments at cementation. This study compared two-piece post and core castings to one-piece castings of the same geometric configuration. The specimens were made with 0.070-inch Whaledent laboratory burnout posts invested in a phosphate investment and cast with Midas, Sturdicast, or Rexillium III alloys. Three groups (n = 10) with two-piece castings had the post cast followed by a second casting of a 1 mm thick core to the post head. Three groups (n = 5) were cast in one piece. The specimens were tested for tension at a head speed of 1 cm/min. One Midas alloy two-piece casting was dislodged at the post head-to-core interface whereas the other specimens failed within the post. There was no significant difference between the two techniques using a generalized linear model (p less than 0.05).

Porcelain-to-composite bond strengths using four organosilane materials.

The flexural strengths of porcelain bonded to composite resin specimens using four organosilane materials were compared. Eighty hand-condensed Vita porcelain specimens were stored in distilled water or ambient humidity before sectioning. Three groups (n = 30) of hydrated specimens were repaired to their original dimensions by using Silux composite resin with Kerr Ultrafine Porcelain Repair Bonding system, 3M Porcelain Kit with ScotchPrimer, or Fusion materials. A fourth group (n = 30) of hydrated specimens was repaired with the DenMat Ultrabond Restorative kit. Four groups (n = 10) of unhydrated specimens were repaired the same as the hydrated specimens. Fracture occurred at the porcelain-to-composite resin interface with three-point loading on the repair interface at 3 x 10(2) mm/min. No difference between Kerr, 3M, and Fusion products, when used with Silux composite resin, was found. The DenMat product had lower strengths. The unhydrated specimens had significantly higher bond strengths than the hydrated specimens with all products.

Coral-Eating Sea Stars Acanthaster planci in Hawaii.

An aggregation of 2 x 10(4) Acanthaster planci was observed from September 1969 to November 1970. The sea stars within the aggregation were very uniform in size, and their reproduction was seasonal. Their average diameter and weight also varied seasonally in a manner that suggests a correlation between average size and breeding condition. The aggregation remained compactly situated in a band a few to tens of meters wide and about 2 kilometers long, parallel to the shore. The band did not move appreciably during the observation period. The sea stars were feeding selectively on a coral which was a minor component of the total coral cover. The coral in the area was predominantly alive, and the proportion of dead coral did not increase appreciably during our period of observation.