A spectrophotometric analysis of dentinal leakage in the resected root.

The purpose of this study was to compare dye leakage in the dentin of resected and nonresected roots. Fifty-four single rooted extracted teeth were used. The two groups were subdivided into young, middle age, and old age samples. Each sample was biomechanically prepared in a standard fashion and obturated using lateral condensation with sealer and gutta-percha. All root surfaces were sealed with nail polish, leaving the apical portion exposed. The apical portion of the roots were placed in 2% methylene blue dye for 72 h, rinsed, and placed in 15 ml of 35% HNO3 for 72 h. The supernatant was analyzed at 640 nm using a visible light spectrophotometer. The amount of leakage was extrapolated from a standard linear regression curve constructed from the stock 2% methylene blue dye solution. The percentage of concentration leakage in all samples ranged from less than 0.0600 to 0.1658. It was concluded that there is a greater amount of leakage in resected versus nonresected extracted teeth. The data also suggest that older teeth exhibit less leakage than younger teeth.     

Measuring Beliefs about Orthodontic Treatment: A Questionnaire Approach

Objectives : Few studies have examined what parents and orthodontists expect from and value about orthodontic treatment. In this study, we designed and tested a questionnaire to outline what drives consumer demand for children's orthodontic care. Further, we present data from the questionnaire to illustrate how expectations and values pertaining to orthodontic treatment relate to sociodemographic variables. Methods : Subjects were 220 Pennsylvania orthodontists and 220 parents at a university orthodontic clinic who were administered a questionnaire designed to assess what parents and orthodontists value about and expect from orthodontic treatment. Items for the questionnaire were developed via a qualitative, telephone interview process. Data were analyzed using factor analysis and reliability analysis for scale development, and analysis of variance for preliminary validity assessment. Results : Through factor analysis, the questionnaire was reduced from 84 to 52 items, and eight scales were examined: expected treatment benefits, expected treatment risks (short- and long-term), expected treatment inconveniences, value of treatment benefits, value of risks (short- and long-term), and value of treatment inconveniences. For parents, the reliability for all scales was in the acceptable range. For orthodontists, only the “short-term risks” scale failed to attain an acceptable reliability. Preliminary validity was assessed through examining relationships between demographic variables and subscale scores. For parents, income, father's education level, and sex of respondent were related to treatment expectations and values. For orthodontists, age, sex, and patient volume were related to treatment values. Conclusions : The questionnaire developed in the present study was found to be practical and reliable for use with providers and consumers of orthodontic care and can be used to explore factors affecting the demand for orthodontic care. Implications of possible unrealistic treatment expectations on the part of orthodontists and parents also are discussed.     

Effectiveness and dentin bond strengths of two materials for reinforcing thin-walled roots.

OBJECTIVES: To investigate the effectiveness of two restorative materials for reinforcing thin-walled roots and their microtensile bond strengths to root canal dentin. METHODS: Twenty-one decoronated maxillary central incisor roots were root filled and the canals enlarged to leave approximately 1.0 mm thick dentin walls. The roots were distributed randomly to three equal groups. Group 1 (control): a large tapered cast post-core was fabricated. Group 2 (BIS-CORE): a thick layer of dual-cured composite was placed in the post-hole before fabrication of a small-diameter tapered cast post-core. Group 3 (ChemFil Superior): a thick layer of glass-ionomer was placed, as before. Metal-ceramic crowns were fabricated for all teeth. Microtensile bond strength tests and optical and atomic force microscope observations were employed to examine adhesion between the two restorative materials and the root canal dentin. RESULTS: Mechanical loading (kN) demonstrated that composite 0.64 (S.D. 0.05), but not glass-ionomer 0.49 (0.05), significantly reinforced the fracture resistance of thin-walled roots, P<0.001. Microtensile bond strengths (MPa) were 21.7 (1.6) for composite and 12.9 (1.7) for glass-ionomer, P=002. SIGNIFICANCE: A thick intermediate layer of resin-bonded composite, sandwiched between the root dentin and a small-diameter cast Ni-Cr post or dowel, increased significantly the fracture resistance of the roots.     

Potential Remineralization of Postorthodontic Demineralized Enamel and the Use of Enamel Microabrasion and Bleaching for Esthetics

Prevention of enamel demineralization during orthodontic treatment is of utmost importance. Should enamel demineralization occur (white spot lesions), early diagnosis and intervention is appropriate. Improved brushing with fluoridated dentifrice and over-the-counter fluoride rinses would be the first recommended intervention. If more aggressive intervention is considered to be necessary due to the extent of demineralized enamel or expected noncompliance with oral hygiene by the patient, professionally applied and/or prescribed fluorides are recommended. Likewise, casein phosphopeptide-amorphous calcium phosphate systems have demonstrated remineralization effects.     

Comparison of apical transportation in four Ni-Ti rotary instrumentation techniques

A new radiographic technique was used to compare apical transportation in four Ni-Ti rotary instrumentation sequences. Mesiobuccal canals of 60 extracted mandibular molars were randomly divided into four groups. Groups 1 and 3 were instrumented by crown-down and groups 2 and 4 by step-back technique with 0.06 ProFiles series 29 to size 6. In groups 3 and 4 Greater Taper files were first used in a crown-down manner. The central axes of initial and final instruments were radiographically superimposed to measure loss of working length (WL) and transportation at 0, 0.5, 1, 3, and 5 mm from WL. ANOVA test showed no significant differences among groups regarding degree of transportation or loss of WL. Transportation was negatively correlated with radius of curvature at 0.5 and 5 mm from WL. The results indicate that the operational sequence of ProFiles or preinstrumentation with GT files has no effect on degree of transportation and loss of WL.     

Elevated antibody to D-alanyl lipoteichoic acid indicates caries experience associated with fluoride and gingival health

Background  

Acidogenic, acid-tolerant bacteria induce dental caries and require D-alanyl glycerol lipoteichoic acid (D-alanyl LTA) on their cell surface. Because fluoride inhibits acid-mediated enamel demineralization, an elevated antibody response to D-alanyl LTA may indicate subjects with more acidogenic bacteria and, therefore, an association of DMFT with fluoride exposure and gingival health not apparent in low responders.     

Combined orthodontic-orthognathic surgical treatment of a Class II, Division 1 malocclusion

This case report shows the need to extract four first premolars in addition to orthognathic surgery, even though the initial treatment plan involved a nonextraction strategy. The extractions were necessary to reduce maxillary dental protrusion and proclination and also to recover from the mandibular incisor proclination that occurred as a consequence of leveling the mandibular arch. (Am J Orthod Dentofac Orthop 1997;111:640-5.)     

Testing causal mechanisms of nonsyndromic craniosynostosis using path analysis of cranial contents in rabbits with uncorrected craniosynostosis.

OBJECTIVE: Various causal mechanisms of familial nonsyndromic craniosynostosis have been presented. One hypothesis suggests that overproduction of bone at the suture is the primary origin of craniosynostosis, which affects brain and cranial growth secondarily through altered intracranial pressure (Primary Suture Fusion Model). Other hypotheses suggest that decreased cranial base growth or abnormal brain growth are the primary cause of craniosynostosis (Cranial Base, Brain Parenchyma Models, respectively). This study was designed to investigate which model best describes neurocranial changes associated with craniosynostosis in a rabbit model through multivariate path analysis. DESIGN: Serial magnetic resonance imaging scans and intracranial pressure measurements were obtained at 10, 25, and 42 days of age from 18 rabbits: six controls, six with delayed-onset synostosis, and six with early-onset synostosis. Five variables were collected from each rabbit: calvarial thickness at the affected suture, cranial base length, brain volume, cerebrospinal fluid volume, and intracranial pressure. This data set was used to test causal pathway relationships generated by the proposed models. Goodness of fit was measured by experimental group for each model. RESULTS: Primary Suture Fusion Model best explained the variables in both delayed-onset and early-onset synostotic rabbits (Goodness of fit = 93%, 97%, respectively). Cranial Base Model (Goodness of fit = 94%) best explained the data in control rabbits. CONCLUSION: Results suggest that the primary site of craniosynostosis in craniosynostotic rabbits is most likely the synostosed suture. Other cranial vault anomalies are most likely secondary compensatory changes. Results of the present study may provide insight regarding the causal pathway of craniosynostosis.     

Safety and efficacy of a nightguard bleaching agent containing sodium fluoride and potassium nitrate.

OBJECTIVES: Transient sensitivity during bleaching is generally reported to affect 67% of patients. While most people tolerate this sensitivity, some find it impossible to continue treatment. The purpose of this study was to determine the safety and efficacy of an experimental, low-sensitivity bleaching agent. METHOD AND MATERIALS: Twenty-two participants bleached for a minimum of 6 hours per night over a 2-week period. The bleaching agent used, Experimental Product E, is a 10% carbamide peroxide gel containing potassium nitrate and sodium fluoride. Evaluations were performed at baseline and 1,2,13, and 26 weeks. Color change was measured using a value-ordered Vita classic shade guide and a colorimeter. Sensitivity of the teeth, gingiva, tongue, and/or throat was measured daily using a patient log. RESULTS: The median color change after 2 weeks was eight tabs. Approximately 36% reported sensitivity during the active whitening phase of the study. As a group, participants reported sensitivity during 13.7% of the total days spent whitening. CONCLUSION: Experimental Product E was shown to be safe. Participants experienced minor sensitivity during the active bleaching phase only. Experimental Product E was shown to be an effective bleaching agent for the subjects tested in this study.