Effects of cyclic loading on selected post-and-core systems.

OBJECTIVE: The purpose of this study was to evaluate the resistance of selected post-and-core systems to fatigue testing. METHOD AND MATERIALS: A fatigue-testing machine and data acquisition software were developed for this in vitro test. Pulpless mandibular second premolars were treated with three different types of post-and-core system: (1) two different prefabricated posts with amalgam cores, (2) the same two prefabricated posts with resin composite cores, and (3) cast post and cores, which served as the control group. The fatigue-testing machine applied alternating buccal and lingual forces to the core until lateral movement of 0.0025 inches (63.5 microns) was detected by a transducer contacting the surface of the core. This criterion represented initial cement failure. RESULTS: Although groups using the resin composite core material exhibited a higher number of cycles prior to failure, there was no statistically significant difference between the different post-and-core systems. CONCLUSION: All of the post-and-core systems that were tested may be acceptable for restoring endodontically treated teeth.

The use of magnets in the comprehensive treatment of congenital partial anodontia: a case report.

This case report describes the treatment of an adult patient with a combination of fixed and removable prosthodontics. The treatment involved increasing the patient's vertical dimension of occlusion, placing two osseointegrated implants, making six surveyed crowns, fabricating a maxillary partial denture, and using magnets to help retain the mandibular partial denture. The clinical steps for using a type of intraoral magnet are described.

Practical, esthetic options for retention of removable partial dentures: a case report.

This case report describes the treatment of an adult patient with a combination of fixed and removable prosthodontics. The patient was very conscious of esthetics and asked to have no clasps showing. Therefore, retentive features that produced good esthetics without being overly complex or expensive were provided. This report describes two less commonly used yet very practical and esthetic retentive features that can be used in many situations.

Retention of complex amalgam restorations using self-threading pins, amalgapins, and Amalgambond.

PURPOSE: To compare the shear fracture resistance of complex amalgam restorations retained by four regular TMS pins, four amalgapins, Amalgambond, or four amalgapins in conjunction with Amalgambond. MATERIALS AND METHODS: Sixty maxillary molars free of caries were mounted in acrylic resin and the occlusal surfaces were ground flat to within 2 mm of the CEJ. The specimens were randomly divided into four groups of 15 teeth. Each group provided one of the four different methods of resistance. Dispersalloy was condensed into the prepared specimens. The specimens were adjusted to provide 4 mm height of amalgam. After 1000 thermocycles, the specimens were loaded at a 45 degree angle to the occlusal surface at a crosshead speed of 1 mm/second. RESULTS: Statistical analysis revealed that Amalgambond, four amalgapins and four amalgapins in conjunction with Amalgambond provided more resistance to shear force than four regular TMS pins.

Tooth loss during compulsory dental care.

The traditional model that teeth are lost due to caries early in life and periodontitis later has been challenged by recent studies. Randomly selected Air Force records were reviewed for the reasons for extractions. Between the ages of 20 to 50, the rate of loss due to caries declined from 0.11 to 0.03, whereas the rate due to periodontitis increased from 0 to 0.34. This study supported the traditional model that tooth loss due to caries decreases with age and that periodontitis is the major cause of loss later in life.

Oral rehabilitation of a patient with congenital partial anodontia using a rotational path removable partial denture: report of a case.

This case report describes the treatment of an adult patient with partial anodontia. Treatment began with the extraction of several retained primary teeth and the insertion of an immediate transitional removable partial denture that was used to evaluate the possibility of increasing the patient's vertical dimension of occlusion. Later, the entire mandibular arch was restored with fixed restorations. Once the vertical dimension of occlusion was established and controlled, the maxillary arch was restored. Metal-ceramic crowns placed on the central incisors were contoured to accommodate a rotational path removable partial denture. The partial denture utilized rigid metal retention on the distal surface of the central incisors instead of clasps. This design produced a very esthetic and stable prosthesis.

The effect of various surface coatings on fluoride release from glass-ionomer cement.

To protect glass-ionomer cement from moisture contamination and dehydration during initial setting, immediate application of a surface coating agent is recommended. This study compared the effect of various surface coatings on F release from glass-ionomer cement. Twenty glass-ionomer cement (Ketac Fil Aplicap) disks (4.52 cm2) were prepared from a Teflon mold. The control group was uncoated, while the experimental groups were coated with Visiobond, Scotchbond II, and Ketac Varnish. In addition, five specimens of Variglass were similarly prepared and remained uncoated as per the manufacturer's instructions. F release was measured each day during week 1 and on the last day of weeks 2, 3, and 4. The results indicated that the application of the surface coatings did not completely inhibit F release from glass-ionomer cements, and that F release during the first week for all groups was significantly greater than in the subsequent 3 weeks. Visiobond-coated glass-ionomer cement allowed significantly more F release than Scotchbond II-coated glass-ionomer cement, Ketac Varnish-coated glass-ionomer cement, or Variglass.

Immersion disinfection of irreversible hydrocolloid impressions with sodium hypochlorite. Part II: Effect on gypsum.

This study investigated the effects of various immersion times and concentrations of sodium hypochlorite on irreversible hydrocolloid impressions and resultant gypsum casts. Irreversible hydrocolloid impressions of a test die were immersed for 1, 5, or 10 minutes in water (control), 5.25%, 0.525%, and 0.0525% sodium hypochlorite and then cast in a Type III stone and a Type V stone. Each stone specimen was evaluated for detail reproduction, dimensional change, surface roughness, and surface hardness. The results indicated that impressions may be immersed in sodium hypochlorite for any of the experimental times and concentrations without negative effects on Type V stone casts. However, immersion of impressions in 5.25% sodium hypochlorite causes some surface deterioration on Type III stone casts.

Fracture resistance of complex amalgam restorations with peripheral shelves used as resistance features.

This in vitro study compared various peripheral shelves (steps) as resistance features for complex amalgam restorations. Three different sizes of peripheral shelves were evaluated: 1 mm x 1 mm, 2 mm x 2 mm, and 1 mm cervically x 2 mm pulpally. The resistance of these features was compared to a control group that utilized two amalgam pins. The 1 mm x 1 mm shelf provided significantly less resistance than the other groups.

The influence of matrix use on microleakage in Class 5 glass-ionomer restorations.

This in vitro study examined the relationship of matrix use to microleakage in class 5 Ketal-Fil glass-ionomer restorations. Class 5 glass-ionomer restorations were placed on the facial and lingual surfaces of 40 extracted human molars. The occlusal margin was located on enamel, and the cervical margin was located on cementum or dentin. Each tooth had one restoration placed with and without the aid of a soft metal matrix. Specimens were thermocycled (1234 cycles, 6 degrees C -60 degrees C, 30-second dwell time) and immersed in 5% methylene blue dye for four hours. The teeth were sectioned occlusogingivally through the center of each restoration, viewed with an optical microscope (X10), and each restoration was scored for dye penetration around the cavity walls. The enamel and cementum margins were scored separately for the extent of marginal leakage. No difference in leakage was found between restorations placed with or without a matrix (P > 0.05). Enamel restorations leaked significantly less than nonenamel margins, regardless of matrix use (P > 0.05).

Correcting space loss caused by severe decay: report of case.

A new application of the brass wire technique was used. Brass wire was used to upright a mandibular second molar that had tipped mesially as a result of severe decay of the adjacent mandibular first molar. This technique allowed proper restoration of the severely decayed first molar and maintenance of an intact dentition.