Spatial agreement of demineralized areas in quantitative light-induced fluorescence images and digital photographs.

OBJECTIVES: Previous work has shown qualitatively that detection of demineralized tooth areas (white spot lesions, WSLs) is more reliable in digital photographs (DP) as in quantitative light-induced fluorescence (QLF) images. Based on non-rigid, multimodal image registration, we now quantitatively compare manual and automatic markings in both modalities. METHODS: After braces removal, pairs of DP and QLF were acquired from 124 teeth of 31 patients. Three experienced raters marked the WSL on both DP and QLF images, each of which was presented twice in randomized order. For each tooth and each modality, a ground truth (GT) was established using the simultaneous truth and performance level estimation algorithm on the total of six manual markings per image. DP and QLF image pairs were spatially registered, by aligning the outline of the tooth area in DPs to that of the corresponding tooth area in QLF. Between all pairs of markings for all teeth, position and size were compared quantitatively by the Dice coefficient and the novel coefficient of inclusion. RESULTS: Our hypotheses: (i) the clinical inspection supported by DP is more sensitive to WSL as that by QLF, disregarding whether the automatic analysis or the experts' manual assessment of QLF is applied, and (ii) detected lesions in QLF are included in those of DP, were confirmed and not confirmed, respectively. CONCLUSION: DP and QLF are valuable methods to detect WSL in demineralized teeth. Combining both modalities can provide additional information on early lesion assessment.

Quantitative light-induced fluorescence images and digital photographs - Reproducibility of manually marked demineralisations.

OBJECTIVE: Hard tooth tissue demineralisation is an undesirable side effect of orthodontic treatment with fixed appliances. Whereas both clinically and in digital photographs (DP), demineralisations appear as white spot lesions, WSLs appear as dark areas when quantitative light-induced fluorescence (QLF) imaging is used. This study aims at comparing the reproducibility of the detection of decalcified tooth areas in DP and QLF. MATERIALS AND METHODS: DP and QLF pairs were acquired from 139 teeth of 32 patients after braces removal. Three raters manually marked the decalcified area on both DP and QLF images. The markings were repeated after 2 weeks. A ground truth was estimated for each tooth and modality using the simultaneous truth and performance level estimation (STAPLE) algorithm. The Dice coefficients (DC) of each rater marking to the ground truth were calculated for all teeth and modalities to quantify the spatial agreement. A three-way repeated measures analysis of variance (ANOVA) was used to compare the means of the DCs for both modalities ([Formula: see text]). Intra-observer and intercycle variabilities were assessed comparing the means across the raters and the cycles for both modalities. RESULTS: ANOVA revealed a statistical significant difference between the modalities [[Formula: see text], [Formula: see text]]. The standard deviation of the DC for the photographs are lower than those for the QLF images. Intra-observer and intercycle differences are rather small as compared to the intermodality differences. CONCLUSIONS: The results indicate a higher spatial reproducibility in identifying a decalcified area on a tooth surface using visual inspection of DP rather than QLF images.

[Uprighting of a tipped lower second molar with the aid of a microscrew anchorage. A case report]. / Aufrichtung eines gekippten unteren zweiten Molaren mit Hilfe von Mikroschrauben-verankerung. Ein Fallbericht.

Titanium microscrews for orthodontic anchorage purposes have been developed in different designs and dimensions by a number of manufacturers. Whereas conventional implants need a relatively extensive bone supply and the insertion sites are limited, microscrews offer a more flexible range of applications. They also offer crucial advantages such as simple, atraumatic insertion and removal, a minimum patient stress and a favourable cost-benefit ratio. In the present case report the successful orthodontic uprighting of a tipped second lower molar using a microscrew demonstrated.

Anchorage quality of deciduous molars versus premolars for molar distalization with a pendulum appliance.

PURPOSE: The aim of this study was to assess dental anchorage qualities when the pendulum appliance is used for distal molar movement. MATERIAL: Thirty adolescents in various dentition stages received a modified pendulum appliance with a distal screw and a specially preactivated pendulum spring for bilateral molar distalization in the maxilla. The subjects were subcategorized into 3 groups of 10 according to the dental anchorage used: deciduous molars, premolars and deciduous molars, or only premolars. Dentoalveolar effects and side effects in the anchorage unit and in the molar area were determined by cephalometric analysis. RESULTS: Statistical analysis of the measurements showed significant differences between groups in the extent of molar distalization and the resulting incisor protrusion. Distal tipping of the 6-year molars was significantly less severe (2.3 degrees +/- 1.58 degrees to the palatal plane and 2.55 degrees +/- 1.52 degrees to the anterior cranial base) in patients with premolar anchorage than in those with deciduous molar anchorage (6.15 degrees +/- 3.42 degrees and 6.35 degrees +/- 3.46 degrees ). Incisor protrusion was significantly more pronounced in patients with deciduous molar anchorage (2.75 +/- 1.4 mm) than in the other 2 groups (1.65 +/- 0.82 mm, mixed deciduous molar and premolar anchorage, and 1.75 +/- 0.75 mm, premolar anchorage). Additionally, incisor protrusion was translatory compared with controlled tipping in subjects with deciduous molar anchorage or premolar and deciduous molar anchorage. CONCLUSIONS: Deciduous molars and premolars can be used for anchorage for molar distalization with a pendulum appliance; however, anchorage with premolars only results in the least pronounced dentoalveolar side effects. The anchorage quality of deciduous molar and mixed deciduous molar/premolar anchorage is limited.

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage.

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG 1 (18 patients), eruption of the second molars had either not yet taken place or was not complete. In PG 2 (15 patients), the second molars had already developed as far as the occlusal plane, with the third molars at the budding stage. In PG 3 (3 patients), germectomy of the wisdom teeth had been carried out, and the first and second molars on both sides had completely erupted. Analysis of cephalograms to identify any changes in the sagittal plane showed that, in the direction of distalization, a tooth bud acts on the mesial neighboring tooth like a fulcrum, and that tipping of the first molars in patients in whom the second molar was still at the budding stage was thus greater. In patients whose second molars had erupted completely, the degree of tipping was greater again when a third molar bud was located in the direction of movement. After previously completed germectomy of the wisdom teeth, almost exclusively bodily distalization of both molars is possible, even without bands being applied to the second molars. However, if the first and second molars are distalized simultaneously with a pendulum appliance, the duration of therapy will be longer, greater forces will have to be applied, and more anchorage will be lost. Statistical analysis of the results of dental-angular measurements showed significant differences in the degree of molar tipping and reciprocal incisor protrusion. The degree of distal tipping of first molars was less in patients with erupted second molars (PG 2 and PG 3) than in those whose second molars were not yet erupted (PG 1). For instance, the measured angles were 0.9 degrees +/- 3.43 degrees (to the palatal plane) and 0.8 degrees +/- 3.4 degrees (to the anterior cranium floor) in PG 2, and -0.33 degrees +/- 0.58 degrees and 0.67 degrees +/- 2.08 degrees, respectively, in PG 3, contrasting with respective values of 5.89 degrees +/- 3.74 degrees and 5.36 degrees +/- 3.49 degrees in PG 1. Tipping of erupted second molars was much more marked in PG 2 (7.92 degrees +/- 5.83 degrees to the palatal plane and 7.55 degrees +/- 5.28 degrees to the anterior cranium floor), but much less pronounced in PG 3 (2 degrees +/- 1.73 degrees to the palatal plane and 2 degrees +/- 2 degrees to the anterior cranium floor) than the corresponding movement of the second budding-stage molars in PG 1 (4.06 degrees +/- 2.15 degrees and 3.97 degrees +/- 2.27 degrees, respectively). The degree of incisor protrusion occurring reciprocally with molar distalization was much less in these patients (measured angles of 3.28 degrees +/- 1.97 degrees and 2.89 degrees +/- 2.17 degrees to the palatal plane and anterior cranium floor, respectively) than in the patients presenting different stages of the dentition (angles of 5.5 degrees +/- 3.33 degrees and 6.03 degrees +/- 4.29 degrees, respectively, in PG 2, and angles of 5.5 degrees +/- 3.28 degrees and 6.67 degrees +/- 3.09 degrees, respectively, in PG 3). Moreover, measurement of dental casts in the horizontal plane showed not only the targeted mesiobuccal rotation of both maxillary molars, but also a vestibular drift of the unbanded second molars.

Radiopacity of fiber-reinforced resin posts.

PURPOSES: (1) To determine the radiopacity of one titanium and seven fiber-reinforced resin posts by densitometric analyses of radiographs, taken from the separate posts and from posts after seating in extracted root-treated human canine teeth with and without a radiopaque luting resin, respectively, and (2) To receive a ranking order by 20 dental practitioners of 16 randomly selected radiographs (2 for each post brand) by radiodensity and by acceptability assessment of the posts' radiographic appearance. MATERIALS AND METHODS: One reference titanium post (1) and the following 7 commercial fiber post brands were investigated: AEsthetiPlus/RTD (2), FiberKor/Jeneric Pentron (3), Light-Post/RTD (4), LightPost/Dentatus (5), Mirafit/Hager & Werken (6), Snowlight/Carbotech (7), and Snowpost/Carbotech (8). Standardized radiographs of the separate posts and of posts in extracted canines both before cementation and after cementation with Panavia 21 EX were produced and evaluated densitometrically together with a reference aluminum step-wedge. The cemented posts' radiodensities were determined from radiographs taken without and with 10 mm Plexiglass shielding. The optical densities were recorded in mm Al equivalents. Sixteen radiographs (2 for each post) were presented in random order to 20 dentists for ranking by decreasing radiopacity and by clinical acceptability scores from good (1), adequate (2), acceptable (3), not acceptable (4), to no radiopacity (5) of the posts' radiographic appearance. Statistical evaluation by ANOVA and Duncan post-hoc test at P< 0.05. RESULTS: Statistically the posts' radiodensities were significantly different. For separate and cemented posts, recorded from radiographs of Plexiglass shielded specimens, respectively, the following Duncan rankings were obtained: 1>7, 8>3>2, 4, 5>6 and 1>7, 8> 3, 5, 2, 6>6, 4. The dentist ranking by radiopacity scores was 1>7, 8>3>5,6>4>2, and by clinical acceptability scores 1>7, 8>3>2, 4, 5, 6. The titanium post (1) and posts 7 and 8 received scores better than acceptable, post 3 was assessed acceptable, whereas posts 2, 4, 5 and 6 were characterized as "not acceptable" or "not radiopaque".

Primary preparation of class II cavities with oscillating systems.

PURPOSE: To assess the effectiveness and side effects of three sonoabrasive systems and conventional rotary cavity preparation. MATERIALS AND METHODS: Standardized artificial carious lesions were placed in 48 human premolars at mesial and distal surfaces. Three dentists prepared eight cavities each using (1) diamond burs, (2) Sonicflex 2000 L/N (HS), (3) an experimental air scaler (HS.EXP), and (4) the Piezon Cavity System (PCS). A small hemispherical preparation tip (Sonicsys micro) was utilized with the airscalers in Groups 2 and 3. Loss of substance was determined by weighing. Residual caries and damage to the adjacent tooth were assessed by two calibrated investigators. Each cavity was digitally photographed prior to planimetrical measuring of its circumferential dimension. Quality of the cavities' margins was examined by SEM. RESULTS: Rotary preparation required less time (4 minutes 53 seconds) than oscillating preparation with HS (6 minutes 45 seconds) or PCS (7 minutes 45 seconds), (Scheffé, P< 0.05). Preparation with HS.EXP (5 minutes 52 seconds) was not different from rotary and HS. 64% of all cavities were completely excavated, 28% showed distinct and 8% marked residual caries. However, chi2-tests did not reveal differences in caries removal between the systems. Oscillating preparation with HS as well as the experimental air scaler in combination with the hemisphere resulted in less trauma to adjacent tooth surfaces than rotary preparation and the PCS system, (chi2-tests P< 0.05). HS.EXP caused less loss of substance (Scheffé, P< 0.05). Regarding circumferential extension of the cavities, there were no differences between the groups.