Quintessence International, 10/2001

Objectives: The purpose of this research was to demonstrate the effectiveness of hydroperoxide ion-phase transfer catalyst (HPI-PTC) cleaners and disinfectants for maintaining dental unit waterlines free of planktonic organisms. Method and materials: Water samples were taken from 117 sites, which included a variety of dental units and samples from the sink faucets of most operatories. Samples were plated on appropriate bacteriologic media and incubated. The presence or absence of biofilms was confirmed by scanning electron microscopy. Twenty-two of the dental units were retrofitted with independent water systems; the cleaning procedure involved an overnight application of an HPI-PTC cleaner followed by a 2-minute water rinse. Results: Water from both the air-water syringe and the high-speed handpiece lines from all untreated units contained at least 6x10² colony-forming units per milliliter of planktonic or free-floating bacteria; the average was 1.4x10⁵ CFU/mL. An initial 5% solution of HPI-PTC successfully cleared the lines of any apparent biofilm when applied for 3 consecutive days. Thereafter, once weekly use of the cleaner maintained the dental unit water supplies free of significant numbers of planktonic organisms. Conclusion: Routine weekly use of an HPI-PTC cleaner controlled dental unit waterline biofilm and reduced, with minimum effort, the microbial contamination level of water used for patient treatment to less than 200 CFU/mL.

Bizarre-appearing gingival recessions that do not correspond to any known gingival disease or oral manifestation of any known systemic disease are called factitial (self-induced) gingival disease. Psychological factors are very important in their etiology. Generally, the lesions occur during the time the child is experiencing stress associated with the frustration of his or her dependency needs. Four cases of self-induced gingival recessions involving children aged 4 to 6 years are presented and investigated from the pedodontic, periodontologic, and psychiatric viewpoints.

Objectives: The purpose of this study was to assess the effect on tooth sensitivity when potassium nitrate and fluoride were added to a 10% carbamide peroxide bleaching gel. Method and materials: Seventeen maxillary and four mandibular arches were bleached using the at-home bleaching technique. The bleaching treatment consisted of the simultaneous use of a 10% carbamide peroxide gel containing 3% potassium nitrate wt/vol and 0.11 fluoride ion wt/vol on one side of the midline and a 10% carbamide peroxide gel only (control) on the other side of the midline for 14 nights. A visual analog scale for each side of the dental arch was used by the patients to assess tooth sensitivity and tooth whitening. Preoperative and postoperative photographs were also taken. Results: The addition of potassium nitrate and fluoride significantly decreased the total tooth sensitivity reported by the patients. The addition did not significantly change the whitening efficacy of the carbamide peroxide bleach. Conclusion: A 10% carbamide peroxide bleaching gel containing potassium nitrate and fluoride produced less tooth sensitivity than did the control bleaching gel during a 2-week at-home bleaching treatment.

Tooth wear occurs during normal mastication. Pathologic wear, including abrasion and erosion, may also take place. Formation of reactionary and reparative dentin and obturation of dentinal tubules are biologic responses that compensate for the loss of tissue. Physical trauma to teeth will affect the blood supply to the pulp. Extensive physical trauma may result in the formation of mineralized, often bonelike tissue in the pulp chamber. Minor trauma, such as that associated with orthodontic tooth movement, may exert transient effects on the pulp or it may result in permanent structural changes. No experimental data involving restorative work on traumatized teeth have been published, but available evidence suggests that special care may be necessary in the restoration of such teeth because their reaction patterns may differ from those in nontraumatized teeth.

Objective: The purpose of this study was to determine the effect of a bidirectional rotation insertion technique on the force necessary to puncture and advance a needle through a tissuelike substance. Method and materials: Two in vitro penetration test models were constructed using different tissuelike substances of different densities. Each tissuelike substance was tested with 30-gauge, 27-gauge, and 25-gauge needles of two brands commonly used in dentistry. The needles were placed to a standardized depth of 0.5 inch (1.27 cm) at a standardized rate of insertion. A customized dental surveyor allowed controlled forces to be applied. A linear insertion technique and a newly described bidirectional rotation insertion technique were tested. The force of puncture and penetration drag was recorded with an electronic digital scale. A total of 400 needle insertions were performed. Results: A multivariate analysis of technique, material, needle gauge, and needle brand revealed the data to be statistically significant, demonstrating no overlap. The post-hoc analysis of between-subject effects found that the needle insertion technique accounted for the most powerful effect in reducing force penetration. The bidirectional insertion technique had the greatest influence on reducing the force penetration irrespective of material, needle gauge, or needle brand tested in this study. Conclusion: The bidirectional rotation insertion technique required two to three times less force than did a standard linear insertion technique. A continuous rotation in a single direction would be expected to produce similar results. Needle gauge and needle design appeared to have a smaller effect on reducing force penetration than did the technique used during insertion. The in vitro model used in this study represents a reliable dynamic testing system that can be used for future evaluation of needles.

Objective: Periotest values for dental implants depend on the type of prosthetic abutment utilized for the restoration. If Periotest value cannot be measured at the single crown, the Periotest values used for comparison must be derived from the same type of superstructure. Method and materials: Fifty-nine patients were selected from a regular follow-up program. At the end of the healing period, the Periotest values of Frialit-2 implants were measured at the gingiva former and abutment. The values were then compared with the Periotest measurements obtained at the placement of the final single crown and during the first follow-up examination. Results: Compared to values measured at single crowns, the Periotest value measured at gingiva formers decreased on average by 3.5. The measurement of the abutment revealed a decrease of 1.7. Until the first recall and under functional loading of implants, the Periotest value increased on average by 1.8. These differences significantly differed from 0. Conclusion: If measurements at different abutments such as crown abutments or single crowns are necessary, comparison of the Periotest values in accordance with the given mean values will lead to more precise results. It is recommended that Periotest measurements be performed for the first and subsequent prostheses, during all prosthetic stages, to allow comparison if some parts of the prosthetic abutment have to be replaced.

Restorations with marginal overhangs are frequently associated with localized periodontal defects. Access to overcontoured approximal margins of restorations can be difficult to obtain, however. A system featuring a multidirectional handpiece is an effective and efficient means of contouring, finishing, and polishing restoration surfaces and margins. In particular, the system facilitates access to approximal and subgingival areas for the removal of marginal excess and overhangs. This system may be a valuable addition to the practitioner's armamentarium for operative procedures.

Objective: The purpose of this study was to assess a new impression material used in conjunction with the dual-arch technique. Method and materials: Ten members were selected at random from the Product Research and Evaluation by Practitioners (PREP) panel, a United Kingdom-based group of dental practitioners who are prepared to undertake research projects in their practices. Explanatory letters, a questionnaire, packs of the impression material, and dual-arch trays were distributed to the evaluators, together with instructions on the use of the materials. The practitioners were asked to use the materials and return the questionnaire after using the materials for a minimum of 10 impressions. Results: Three evaluators had not previously used the dual-arch technique, six had used it in the past or occasionally, and one used the technique routinely. A total of 115 impressions were recorded with Quick Step. The overall rating for ease of removal of impressions from the mouth was 4.7 on a linear scale in which 5 represented easy to remove and 1 represented difficult to remove. Four of the evaluators rated the working time as excellent and the remaining six as good. Eight of the evaluators stated that the quality of fit of the single-unit restoration constructed with the combined-arch tray was the same as that obtained when a conventional tray technique was used. Conclusion: The impression material under test scored highly for application in circumstances where the fields above and below the preparation margin were dry or had limited moisture problems. Eighty percent of the evaluators considered the impression and dual-arch tray technique to be of benefit to their practice.

Objective: This investigation evaluated the leakage (diffusion) of lipopolysaccharide and dextran beneath cast-gold crowns luted with one of three cements. Method and materials: Thirty extracted molars were prepared for crowns. Thirty crowns with access ports (facial or lingual) were cast in gold and luted to their preparations with zinc phosphate, glass-ionomer, or an adhesive resin cement (10 per group). Teeth and crowns with filters inserted in the ports were immersed in a solution of labeled macromolecules (tetramethylrhodamine isothiocyanate-labeled lipopolysaccharide and fluorescein isothiocyanate-labeleddextran) and evaluated for leakage at 2 weeks and 1, 2, 3, 4, 5, and 6 months. Filters were retrieved and analyzed with microfluorimetry. Results: No filters retrieved from any crowns demonstrated any detectable leakage, and all filters were negative for both dextran and lipopolysaccharide for all evaluation periods. Conclusion: For the 6 months of this investigation, zinc phosphate, glass-ionomer, and adhesive resin cements were equally effective at preventing leakage of detectable molecular concentrations of lipopolysaccharide and dextran to the level of the access ports in the absence of thermal or mechanical stress.