Using a repositioning splint to determine reproducibility in the color registers of a dental spectrophotometer.

OBJECTIVES: The purpose of this study was to assess if the use of intraoral positioning guides could increase the reproducibility of color measurements with a dental spectrophotometer. METHODS: Twenty-three subjects were selected, and positioning guides for the maxillary arch of each participant were fabricated with clear 4 mm thermo-sheets. One orifice was made in the center of the clinical crown of the upper-right central incisor and another in the canine, with an external 6 mm diameter trephine. Color measurements were performed with a Vita EasyShade Compact IV dental spectrophotometer by the same operator in the same conditions. Forty measurements were taken per patient, 20 for each tooth, 10 with a positioning guide, and 10 without one. Before each measurement, the spectrophotometer was calibrated following the manufacturer's instructions. RESULTS: Using the Wilcoxon test to evaluate nonparametric variables, there are statistically significant differences (P < .05) between the use or not of positioner for color recording with spectrophotometer. Greater repeatability of the measurements is obtained using repositioning split. CONCLUSIONS: Within the limitations of this study, the use of positioning guides provides greater reproducibility in spectrophotometer measurements for all parameters of tooth 11 and for some parameters of tooth 13. CLINICAL SIGNIFICANCE: The use of a positioning guide for color measurement with a dental spectrophotometer allows a greater reproducibility of the measurements to be obtained. Achieving repeatable measurements is essential for studying the same area of the tooth, for example, in bleaching treatments and in color checks for prosthetic treatments.

Influence of treatment duration on the efficacy of at-home bleaching with daytime application: a randomized clinical trial.

OBJECTIVE: The aim of this study is to determine whether prolonging the daytime at-home bleaching treatment by 1 week increases the bleaching effect without causing more side effects. MATERIALS AND METHODS: Fifty participants were randomly divided into two groups, (A) with a 14-day treatment and (B) with a 21-day treatment. A gel with 10% carbamide peroxide was applied for 2 h a day in custom trays. Color measurement was performed using a dental spectrophotometer on the right maxillary central incisor and the canine at baseline, at the end of treatment, and 1 and 6 months afterwards. Daily, participants recorded their tooth sensitivity and gingival irritation. RESULTS: At the end of the treatment, the ΔE00 of group B (5.77 ± 2.15) was significantly higher than the ΔE00 of group A (4.74 ± 1.94) (p = 0.005 (95% CI: - 2.13 to - 0.39)). After 6 months, tooth color was more stable in group B. The ΔSGU values between the different appointment times were higher in the 3-week group. Participants from group B reported more side effects, but statistically, there were no differences compared with group A (p = 0.225 for tooth sensitivity and p = 0.758 for gingival irritation). CONCLUSIONS: Daytime application of at-home bleaching for 3 weeks achieves greater bleaching results than for 2 weeks, immediately after treatment and 1 and 6 months afterwards. However, slightly more side effects could occur. CLINICAL RELEVANCE: When daytime application of at-home bleaching is required, the treatment duration should be prolonged from 2 to 3 weeks to achieve greater and more stable results.

Jaw biodynamic data for 24 patients with chronic unilateral temporomandibular disorder.

This study assessed 24 adult patients, suffering from severe chronic unilateral pain diagnosed as temporomandibular joint (TMJ) disorder (TMD). The full dentate patients had normal occlusion and had never received an occlusal therapy, i.e., were with natural dental evolution/maturation. The following functional and dynamic factors were assessed: (1) chewing function; (2) TMJ remodeling or the condylar path (CP); and (3) lateral jaw motion or lateral guidance (LG). CPs were assessed using conventional axiography, and LG was assessed by K7 jaw tracking. Seventeen (71%) of the 24 (100%) patients consistently showed a habitual chewing side. The mean (standard deviation [SD]) of the CP angles was 47.90 (9.24) degrees. The mean (SD) of the LG angles was 42.95 (11.78) degrees. Data collection emerged from the conception of a new TMD paradigm where the affected side could be the habitual chewing side, the side with flatter lateral jaw motion or the side with an increased CP angle. These data may lead to improved diagnosis, therapy plans and evolution in TMD patients.

Long-term clinical evaluation of Dyract compomer in the restoration of non-caries cervical lesions: A 20-year retrospective study.

OBJECTIVE: The restoration of non-caries cervical lesions has long been a challenge. Until recently, compomers were the restorative materials of choice. The aim of this in-vivo study was to evaluate the long-term clinical performance of Dyract restorations in non-caries cervical lesions. METHOD AND MATERIALS: Forty-two patients with Dyract restorations of non-caries cervical lesions performed in 1995 by the same operator were included in this in-vivo retrospective study. After 20 years, restorations were evaluated by two calibrated examiners following the USPHS criteria modified by Ryge. RESULTS: After 20 years, 38 of the 54 restorations included in this study remain in service (70.4%). Debonding was the cause of all failures. Marginal adaptation and marginal discoloration were the categories with poor values. CONCLUSION: Dyract restorations can be considered a treatment option for non-caries cervical lesions, because they show good long-term clinical performance for 20 years. CLINICAL RELEVANCE: Dyract restorations continue to be an option to restore non-caries cervical lesions, due their good long-term clinical performance and the ease of the clinical procedure. The survival rate of these Dyract restorations was high after 20 years (70.4%). However, the limitations of marginal discoloration, marginal adaptation, and color match should be considered.

Titanium posts and bonded amalgam core longevity: A 22-year clinical survival retrospective study.

BACKGROUND: The authors conducted a retrospective study to evaluate the long-term (18-22 years) clinic results of titanium post and bonded amalgam core restorations with metal-ceramic crowns placed in patients. METHODS: From 1992 through 1996, the authors placed 88 restorations in 66 patients. They measured the ferrule effect in the minor dentin collar area. In 2014, the authors analyzed the following variables: ferrule length, length and thickness of the post, and tooth position. RESULTS: The overall survival of the restorations decreased over time with survival rates of 89.6% after 5 years of follow-up appointments and 64.2% after 18 years of follow-up appointments. There were 42 failures, and the maxillary premolars had the most failures. The teeth with 2 or more millimeters ferrule length had a higher survival rate than those with a 0 to less than 2 mm ferrule length; these results were not statistically significant. CONCLUSIONS: Statistically significant differences were detected according to the location of the tooth. The cores in the anterior teeth were 3.26 times more likely to fail than those in the molars, which presented higher survival rates; maxillary premolars had the most failures (28.5%). Both the metallic post length and its diameter did not influence restoration survival. The ferrule length was not statistically significant. PRACTICAL IMPLICATIONS: The clinical technique to restore endodontically treated teeth that includes a titanium post and bonded amalgam restorations results in greater coronal destruction but shows good long-term results, ease of fabrication, and modest cost in comparison with other techniques.

Mechanical properties related to the microstructure of seven different fiber reinforced composite posts.

PURPOSE: The aim of this in vitro study was to evaluate the mechanical properties (bending strength and hardness) of seven different fiber reinforced composite posts, in relation to their microstructural characteristics. MATERIALS AND METHODS: Two hundred eighty posts were divided into seven groups of 40, one group for each type of post analyzed. Within each group, 15 posts were subjected to three-point bending strength test, 15 to a microhardess meter for the Knoop hardness, and 10 to Scanning Electron Microscope in order to determine the diameter of the fibers and the percentage of fibers embedded in the matrix. To compare the flexural strength in relation to the type of fiber, matrix, and the hardness of the posts, a Kruskal-Wallis H test was used. The Jonckheere-Terpstra test was used to determine if the volume percent of fibers in the post influenced the bending strength. RESULTS: The flexural strength and the hardness depended on the type of fibers that formed the post. The lower flexural strength of a post could be due to deficient bonding between the fiber and the resin matrix. CONCLUSION: According to the results, other factors, besides the microstructural characteristics, may also influence the mechanical properties of the post. The feature that has more influence on the mechanical properties of the posts is the type of fiber.

A study of in vivo degradation of two vital home bleaching gels.

This study investigated hydrogen peroxide (H2O2) concentration of two home bleaching gels, in their dispensing syringes and their degradation in vivo in intraoral bleaching trays. Two bleaching gels were studied, 7.5% hydrogen peroxide (HP) and 20% carbamide peroxide (CP). The concentration of H2O2 was determined in dispensing syringes. Twenty individuals were involved in this study. The gels were placed in trays of both arches and their degradation determined at 5, 10, 15, 20, 30, 40, 60 and 75 min. The concentrations of H2O2 in syringes were (HP) 8.12% and (CP) 7.95%. For the HP gel in custom-trays the concentration of H2O2 was 73% at 5 min and 42% after 75 min. In the 20% CP gel it was 75% at 5 min and 39% after 75 min. Activity decreased linearly up to 75 min, where the mean concentration of H2O2 exceeded 35% for the CP and HP gels.

A standardised protocol for the quantification of lactate dehydrogenase activity in saliva.

UNLABELLED: The literature about salivary lactate dehydrogenase (LDH) activity shows different results, conditioned by the diversity of methods used for sampling, handling and analysis. OBJECTIVES: The aim of this study was to design a protocol for quantifying salivary lactate dehydrogenase activity. METHODS: Whole saliva samples were collected from 100 healthy volunteers by chewing a roll of cotton. Lactate dehydrogenase activity determinations were made with the Cobas Mira Plus II autoanalyser using the recommendations proposed by the International Federation of Clinical Chemistry (IFCC) and the French Society of Clinical Biology (SFBC). Samples were stored at room temperature (20-22 degrees C), in the refrigerator (4 degrees C) and freezer (-20 degrees C). The correction capacity of the autoanalyser was evaluated by making serial determinations in samples of saliva diluted in water. RESULTS: The frozen samples, but not those stored in the refrigerator or at room temperature, showed an important degradation of lactate dehydrogenase activity. When the samples were diluted in water, the lactate dehydrogenase activity varied substantially with the International Federation of Clinical Chemistry method after correction, but not when using the French Society of Clinical Biology method. CONCLUSION: For salivary lactate dehydrogenase activity quantification we suggest that samples be stored at 4 degrees C and analyse with the French Society of Clinical Biology method.

Inlays de metal-porcelana como retenedores de prótesis fija / Metal ceramic inlays as retainers for fixed prostheses

En ocasiones, las prótesis fijas convencionales resultan un tratamiento demasiado agresivo para los dientes pilares. El desarrollo de las técnicas adhesivas nos ha permitido diseñar puentes más conservadores. En este artículo detallamos una técnica para la elaboración de puentes retenidos mediante incrustaciones metal-cerámicas adheridas. El uso de inlays estaría indicado cuando se deben sustituir uno o dos dientes en tramos rectos de los sectores posteriores. La mayor conservación de los tejidos dentarios nos facilita una mejor estética y es más aceptado por los pacientes. Asimismo, como el inlay sólo ocupa una porción del perímetro dentario conseguimos una mayor salud periodontal. Clínicamente el tallado y la toma de impresiones se simplifica considerablemente (AU)

Construcción de muñones de amalgama adherida en dientes severamente destruidos / Bonded amalgam cores building-up in severaly destroyed teeth

El empleo de las técnicas de poste y muñón confeccionado directamente en clínica cada vez goza de mayor aceptación. En el presente artículo describimos la técnica para la obtención de un muñón de amalgama sobre dientes con lesiones destructivas que han obligado a dejar los márgenes subgingivalmente. En estos casos la amalgama es el mejor material de restauración directa. Como sistema de retención empleamos postes de titanio Unimetric y como mecanismo antirrotacional otro poste o un 'amalgampin'. La mayor dificultad del empleo de amalgama es aislar el campo operatorio y conseguir una matriz suficientemente estable que nos permita condensarla en su interior. El aro de cobre puede conseguir estos dos objetivos. Adaptándose íntimamente al contorno dentario consigue una gran estabilidad y nos aísla el diente de sangre y fluidos (AU)