Immediate loading and implant-bar overdenture.

Immediate loaded implants may be used with an implant-bar overdenture to provide fixed splinting. This is a relatively new system that provides for immediate implant placement and restoration.

The effect of impression volume and double-arch trays on the registration of maximum intercuspation.

STATEMENT OF PROBLEM: The type of double-arch trays used may affect occlusion. PURPOSE: The purpose of this study was to determine what effect, if any, double-arch tray design and impression material volume had on the registration of maximum intercuspation (MI). MATERIAL AND METHODS: Quadrant impressions were made on articulated fracture-resistant dental casts mounted in maximum intercuspation occlusion. Three types of sideless double-arch impression trays were used: First Bite with nylon webbing, Sultan's 3-Way with double crosshatch webbing, and Premium's 3-in-1 Tray with single crosshatch webbing. Vinyl polysiloxane impression material (Aquasil Ultra Rigid Fast Set) was distributed at 2 different volumes (5.4 ml and 8.3 ml), and 60 impressions were made (n=10). A weight of 1.2 kg was placed on the upper arm of an Artex articulator, ensuring complete closure. The impressions were allowed to polymerize for 5 minutes. After polymerization, specimens were placed on a light box, and a camera set at a fixed distance was used to capture the light transmission that was projected through the impression material. The camera transferred the information to an image analysis program (ImageJ). This system allowed the different amounts of light projected through the impression to be translated into a gray scale value (GSV), which was assigned a thickness value, in millimeters, of a specified occlusal contact area. To assess reliability of the experimental design, 10 control impressions were made by directly applying impression material onto the typodont. These were analyzed in the same manner as the impressions made with trays. A 2-way ANOVA comparing volume by tray type was used (alpha=.05). This was followed by a Tukey HSD test. RESULTS: There was no main effect for volume of impression material (P=.71). Tray type was significantly different (P<.001). Impressions made with Sultan trays were significantly less accurate than impressions made with First Bite or Premium impression trays. The Premium tray type had the highest mean (SD) GSV, 179.8 (8.1), significantly higher than First Bite (164.7 (19.8); P<.001) or Sultan (82.8 (7.4); P<.001) trays. CONCLUSIONS: This in vitro study demonstrated that certain trays hinder closure into MI, which may negatively affect the accuracy of record making.

Communication: a case against underocclusion.

Hypo-occlusion is another term for underocclusion. This condition is often caused during crown-and-bridge procedures where an incorrect mounting of opposing dental casts, the injudicious polishing of the occlusal surface of a cast restoration, or the intended placement of an occlusal shim prior to the casting will guarantee a close occlusal contact--one that doesn't make contact. Hypo-occlusion may also take place during routine restorative work where the clinical operator "ditches" the restoration for assumed longevity. Implant specialists often advocate to the restorative dentist that their implants should be constructed with no lateral interferences and with a light centric contact or one that is just underocclusal contact. What exactly does this mean?

Know your indicator.

Recently, someone asked me what kind of occlusal indicator I used to determine occlusal contacts. I thought about it, but I couldn't give a definitive answer. Then I did a library search, but didn't get very far since there are few papers on this subject. There are also no American Dental Association standards on the subject. So I figured out a way to see for myself. This is not a scientific paper and there are no statistics. But I can visually see a difference. I am working within the "least-damaging principle, " which relates to the adage of "do no harm. "

An effective method for spreading flowable composites in resin-based restorations.

UNLABELLED: Cavity lining with flowable composites has been suggested for better marginal adaptation and a reduction in interfacial stress and post-operative sensitivity. The following in vitro study compares the spreading of flowable composite that lines the inner wall of a test cavity using an explorer and a specially designed smooth, oscillating, off-center rotating bur spun at 300 to 600 rpm. Two commercial flowable materials were used in this study. RESULTS: With use of the rotating bur, a more consistent, uniform cavity lining was achieved. This was not possible using the dental explorer. CONCLUSION: The specially designed rotating bur provides an effective way for clinicians to form a uniform cavity lining.

Influence of eugenol contamination on the wetting of ground and etched dentin.

Forty third molars were sectioned parallel to the occlusal surface in order to expose superficial and deep dentin. Exposed surfaces were ground flat with 500-grit sandpaper. Contact angle measurements were performed to assess wettability using the ADSA-CD technique. Specimens were divided into two groups. Group 1 was the control group (no contamination). Group 2 served as the test group. Dentin surfaces were covered with a provisional eugenol-containing material (IRM) and were placed into a humidor at 37 degrees C for one week. The provisional material was removed. Wettability measurements of the two groups were made with water on ground dentin, with water and resin on etched dentin. Data were statistically analyzed by ANOVA, Student-Newman-Keuls multiple comparison and Student t-tests. Eugenol contamination did not affect the dentin wetting. Acid etching significantly diminished contact angle values. Dentin wetting was greater on deep dentin than on superficial dentin.