The aim of the study was to evaluate the precision of a reflectance spectrophotometer during longitudinal assessment of tooth colour in vivo. The spectrophotometric data of five standardized circular areas on the labial surfaces of six teeth (four upper and two lower), from 22 dental students, were recorded on three separate days (1st, 3rd and 30th) employing a repeated-measuring design (n = 3). Total colour differences were calculated according to the equation DeltaEpsilon = [(DeltaL*)(2) + (Deltaa*)(2) + (Deltab*)(2)](1/2). It was found that all measured teeth areas, recorded by the same examiner (DeltaEpsilon(INTRA)), demonstrated minor colour changes during the three different time intervals, which did not exceed in every case the 50:50% perceptibility threshold of DeltaEpsilon = 1, thus indicating a good match. The smallest DeltaEpsilon values were recorded for the upper central incisors, whereas lower central incisors and upper first premolars revealed the most significant colour differences (0.68 +/- 0.21 and 0.70 +/- 0.25 DeltaEpsilon-units, respectively). The central zone of the middle third of each labial tooth surface exhibited the most precise recordings. With regard to interexaminer reproducibility (DeltaEpsilon(INTER)), the mesial and distal areas of all measured teeth presented the most statistically significant colour differences (0.48 +/- 0.15 and 0.50 +/- 0.17 DeltaEpsilon-units, respectively). It is concluded that the spectrophotometer tested in the present study can provide a precise measurement of tooth colour in vivo. However, in rejection of the null hypothesis, the type (posterior teeth, mandibular incisors) and the mesial and distal areas of natural teeth affected the repeatability and reproducibility of intraoral spectrophotometric measurements.
The results of this study have shown that the presented intraoral appliance is an effective and reliable means of distalizing first and second maxillary molars simultaneously without the need for patient compliance. Appliance effects are limited primarily to the dentoalveolar structures. Mesial movement and slight protrusion of the anchorage unit have to be taken seriously into consideration during intraoral distalization.
To assess the in vivo colour alterations of two different clear thermoplastic retainers. Methods: Thirty patients were randomly allocated into two Groups (N = 15) following the completion of active orthodontic treatment. Group 1 received Vivera® and Group 2 Essix® C+ thermoplastic retainers. Each patient was provided with two fabricated retainers (one for use and the other to serve as a control). The CIELAB parameters of the patients' upper central incisors were measured with a SpectroShade™ spectrophotometer immediately after retainer placement (T 0 ) and again after 15 days (T 1 ), one month (T 2 ) and three months (T 3 ). The measurements were also performed on teeth without the retainer in place. ΔE differences were calculated. Results: ΔE changes from T 0 to T 1 , T 2 or T 3 showed no statistically significant differences between Groups 1 and 2 within any combination of measurements or teeth. ΔE (T3-T0) changes for used retainers were 1.55 times higher than control appliances (p = 0.002) and 1.44 times higher than for teeth-only (p = 0.004). For used retainers, changes between T 3 and T 0 were 1.56 times higher than between T 1 and T 0 and 1.47 higher than between T 2 and T 0 (p < 0.001). There were no statistically significant differences in ΔE between teeth 11 and 21. Conclusions: Used retainers exhibited greater colour change than control appliances or teeth-only readings, and increased commensurate with the duration of use. Vivera® and Essix® retainers exhibited similar colour stability. All differences observed were considered clinically acceptable (ΔE < 3.7), although prolonged use could cause clinically significant colour changes.
The new moisture-resistant adhesive systems under study were found to be clinically efficient, though Assure exhibited a significantly higher bond failure rate than Unite and Transbond MIP. The higher frequency of adhesive failures observed with Assure might indicate a possible weak point at the adhesive-bracket interface.
Structured Abstract
Objectives
To assess in vivo colour alterations of teeth following removal of fixed orthodontic appliances during retention.
Setting and Sample Population
The Department of Orthodontics at the Aristotle University of Thessaloniki. Forty‐eight patients after orthodontic treatment.
Material and Methods
Debonding and cleaning procedures after orthodontic treatment were performed using two different carbide burs attached to a low or high‐speed handpiece, respectively, in a non‐blinded cohort study with split‐mouth design. Spectrophotometric colour data of teeth were recorded: (a) after debonding, (b) three months later, prior to and following finishing with Soflex discs, and (c) after 1 year. The CIE Lab colour parameters were measured for each tooth, and the corresponding ΔΕ differences were calculated. The effect on colour was assessed with 3‐way mixed ANOVA and Bonferroni's comparisons test (a < 0.05).
Results
Orthodontic debonding and cleaning procedures were found to have statistically significant effects on the CIE colour parameters of treated teeth, since the L* values decreased 0.6 units (P < 0.001), a* values were stable (0.0 units) and b* values increased 1.4 units (P < 0.001), during the first retention year. Finishing temporarily decreased the enamel colour differences. Total ΔΕ differences for all types of teeth measured ranged from 1.4 to 2.1 units. The greatest changes were exhibited during the first 3 months in teeth on which high‐speed rotary instruments were used (1.6 units).
Conclusion
The clinical relevance of this study points out that the colour of natural teeth following removal of fixed orthodontic appliances changes in long‐term.
Further investigations focused on the improvement of the physical and mechanical properties of the water-activated bonding system are needed to make it a reliable alternative adhesive for the direct bonding of orthodontic brackets.
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