Quintessence International, 03/2003

When single-tooth implants are not appropriate, the use of resin-bonded fixed partial dentures is a preferred treatment option when the abutments are relatively sound. However, the use of resin-bonded fixed partial dentures (RBFPDs) for replacing two or more missing teeth is considered to have a guarded prognosis, as long-span RBFPDs have been shown to be less successful than single pontic prostheses. The use of properly modified nonrigid connectors may well improve the success of long-span RBFPDs by reducing harmful interabutment stresses that appear to be responsible for retainer debonding in long-span RBFPDs. For such long-span prostheses, it is advised that the major retainer have wraparound on at least three surfaces of the abutment or have strategically placed opposing axial grooves or slots. It is considered essential that the connector allow interabutment movement in both the horizontal and vertical planes so that the retainer with the greater resistance and retention form does not stress and possibly debond the minor retainer. The upside-down positioning of the nonrigid connector and the matrix incorporated with the major retainer is considered important for successful maintenance, if a debond should occur due to greater loading on the major retainer, because it can be removed and recemented easily. Clinical cases are described that replace two or more missing teeth using fixed-movable RBFPDs with nonrigid connectors.

Objective: The increased popularity of alumina-based restorations has resulted in an interest in proper adhesive techniques to assure a strong and predictable bond to these restorations. This study investigated the early bond strength of three different resin-cement systems to densely sintered alumina (aluminum- oxide ceramic) with and without the use of their corresponding silane coupling agent (silanization). Method and materials: Ninety samples of densely sintered high-purity aluminum-oxide ceramic were randomly divided into three groups. Composite cylinders were bonded to the ceramic samples with three resin-cement/bonding-agent systems: Noribond DC (NOR), Panavia 21 EX (PAN), and Variolink II (VAR). Each resin-cement/bonding-agent system was used with and without their corresponding silane (SIL) coupling agent (n = 15). After fabrication, the specimens were stored in distilled water for 3 days at room temperature, and shear bond strength was tested. Results: Application of the silane-coupling agent on sandblasted densely sintered alumina did not significantly influence bond strengths with PAN. Silanization significantly improved shear bond strengths with NOR and VAR. NOR-SIL and VAR-SIL revealed the statistically highest values, with NOR-SIL showing the highest mean bond strength of all groups. Conclusions: Silanization of sandblasted densely sintered alumina had mixed effects on the applied resin cements: It had no effect on the performance of the phosphate-modified resin cement PAN, but significantly improved shear bond strength of the Bis-GMA composite resin cements VAR and NOR. NOR-SIL revealed the highest overall mean bond strength.

This article describes a convenient technique for making impressions of complete dentures using two newly developed silicone materials. One of these materials, a heavy-bodied silicone material, is used for simultaneous molding of all borders. The material is available in automatic mixing systems, so it can be easily and evenly applied on the tray borders. The material is designed to have a low elasticity after setting so that excess material can be carved or deficient sites corrected with a small mix. The other newly developed material, a light-bodied silicone material, possesses better flow than the usual light-bodied silicones. In addition, since viscosity is controlled and adequate flow is maintained during seating in the mouth, mucosal detail is superior.

The quantitative light-induced fluorescence (QLF) method is based on the natural fluorescence of teeth. Currently, the method is predominantly used in vitro and in clinical studies for early detection of carious lesions and for monitoring of de- and remineralization of white spots by quantifying the mineral loss and the size of smooth surface lesions. The objective of this paper was to demonstrate the potential of QLF for application in routine dental care. Experience with QLF was reported by selected cases, which enlightened the advantages of the method for caries detection and for evaluation of preventive interventions in caries-prone patients in daily practice.

Objective: The objective of this investigation was to measure and compare the dimensions of casts made using four types of impression trays and two impression materials to the dimensions of the original master model. This study differed from previous studies by using three-dimensional measurement. Method and materials: Vinyl polysiloxane and polyether impressions were made of two crown preparations of ivorine teeth cemented into an acrylic master model. Two grooves were placed into each of the preparations. In addition, six points were placed on each occlusal surface and six were placed on each finish line. Impressions were poured with a Type IV dental stone at 48 hours. A three-dimensional measuring system was used to determine coordinates of 32 points on the master model and resulting casts. Inter- and intratooth dimensions were calculated from the measured coordinates. Results: The accuracy and precision of the impression techniques were assessed using analysis of variance (ANOVA) and Dunnett's t test. The ANOVA and Dunnett's t test indicated that only the custom tray did not detect any inaccuracies and was as reproducible as the master model. Conclusion: This study suggests that the custom tray technique is most accurate, even though all other techniques evaluated apparently produce clinically acceptable results.

Objective: The aim of this in vitro study was to compare the retention of five different esthetic post systems of similar dimensions in extracted teeth using titanium posts as controls. Method and materials: Sixty recently extracted single-rooted, caries-free teeth were sectioned horizontally and mounted in acrylic resin. The samples were randomly allocated into six groups of 10 for post preparation. Post space preparation was carried out according to the individual manufacturer's instructions. All posts were bonded using Panavia F. A 4-mm hollow, metal sleeve was luted over the free end of each post prior to mounting in a universal testing machine, and the forces required to dislodge the posts using a cross-head speed of 5 mm/min were recorded. Results: It was found that the parallel-sided Lightposts were significantly more retentive than all of the other posts. Parapost Fibrewhite posts were more retentive than tapered Lightposts and Snowposts. There was no significant difference between the retention of stainless steel Paraposts and any of the other groups. Conclusions: Serrated parallel-sided stainless steel posts were no more retentive than either parallel-sided or tapered tooth-colored posts in this study. When all groups were considered, post dimension appeared to influence retention, with parallel-sided posts being more retentive than tapered posts.

The application of the rubber dam (dental dam) is indicated in endodontics and for restorative dental treatments involving the acid-etch technique. The frequency of the technique's use varies significantly according to individual circumstances, and is generally too low given its advantages. One possible reason for many dentists' reluctance to use it could be frustrating results in the past with technically difficult applications. Such conditions arise, for example, when the taut rubber dam sheet exerts too much pull on the rubber dam clamps, causing them (and the entire rubber dam) to come loose. Particularly susceptible here are clamps attached to molars. This undesired tension results from stretching the rubber dam material-a necessary step-for attaching the sheet to the traditional rubber dam frame. As an alternative, a new easy-to-use rubber dam frame (Safe-T-Frame) has been developed that offers a secure fit without stretching the rubber dam sheet. Instead, its "snap-shut" design takes advantage of the clamping effect on the sheet caused when its two mated frame members are firmly pressed together. In this way the sheet is securely attached, but without being stretched. Held in this manner, the dam sheet is under less tension, and hence, exerts less tugging on clamps-especially on those attached to molars. Even in cases where there are no distinct anatomic undercuts, this lack of tension in the sheet eases isolation procedures and permits the use of standard rubber dam clamps. As a further benefit, the frame's raised edging provides a barrier around the sheet, which prevents small amounts of fluids from escaping. This contributes to greater patient comfort.

A 53-year-old Caucasian female presented to the Oral Medicine Department at the hospital of the University of Pennsylvania for consultation regarding facial pain. A panoramic radiograph revealed multilocular radiolucencies in the right articular eminence. A CT scan was then performed, and the radiolucencies were determined to be pneumatization of the articular eminence.

Congenital neutropenia is characterized by a severe reduction in absolute neutrophil counts, resulting in an almost total absence of neutrophils. It is well known that severe neutropenia affects periodontal status. Oral manifestations include ulcerations, gingival desquamation, gingival inflammation, attachment loss, and alveolar bone loss which may result in tooth loss. Treatment with granulocyte-colony stimulating factor (G-CSF) may improve this periodontal condition. This article reports the relationship between periodontal disease status and peripheral neutrophil levels in two consanguineous siblings with severe congenital neutropenia who did not receive routine G-CSF for 2 years prior to examination. Both siblings were given scaling, root planing, and periodontal prophylaxis in regular follow-up visits. This report demonstrates that periodontal therapy supported by adequate oral hygiene may result in restoration of neutrophil counts in siblings with congenital neutropenia.

Objectives: The purpose of this study was to identify the most frequently encountered predisposing factors in relation to the etiology of pericoronitis in young adults and to compare these findings with similar studies. Method and materials: The patients included in this prospective study were those presenting for treatment of signs and symptoms of pericoronitis in the mandibular third molar area during an 8-year period from 1994 to 2001. A standard check sheet of subjective and objective observations was completed, and female patients were asked about menstruation or pregnancy. Each patient with a diagnosis of pericoronitis was interviewed and observations were recorded. Patients were asked about the symptoms relating to the pericoronitis. Patients were divided into five 5-year age groups ranging from 16 to 40 years. Results: During the 8-year period, 2,151 patients presented diagnosed cases of pericoronitis; 932 (43.3%) patients were male and 1,219 (56.7%) were female. The peak age of occurrence of pericoronitis varied from 21 to 25 years (55.2% of the patients). The incidence of pericoronitis was highest in September (207 [9.6%]), followed by April (181 [8.4%]); for subacute pericoronitis, the highest was in February (128 [5.95%]) and April (112 [5.2%]), followed by October (97 [4.5%]). The most frequently seen predisposing factor was upper respiratory tract infection in 815 (37.9%) patients, followed by stress in 473 (22%) patients. Conclusion: It was concluded that the upper respiratory tract infection was the most frequently predisposing factor, which could precipitate pericoronitis.