New insights in the reproducibility of visual and electronic tooth color assessment for dental practice.

BACKGROUND: The aim of the study was to compare a 2D and 3D color system concerning a variety of statistical and graphical methods to assess validity and reliability of color measurements, and provide guidance on when to use which system and how to interpret color distance measures, including ΔE and d(0M1). METHODS: The color of teeth 14 to 24 of 35 patients undergoing regular bleaching treatment was visually assessed and electronically measured with the spectrophotometer Shade Inspector™. Tooth color was recorded before bleaching treatment, after 14 days, and again after 6 months. VITAPAN® Classical (2D) and VITA-3D-Master® (3D) served as reference systems. RESULTS: Concerning repeated measurements, the 2D system was superior to the 3D system, both visually and electronically in terms of ΔE and d(OM1), for statistics of agreement and reliability. All four methods showed strong patterns in Bland-Altman plots. In the 3D system, hue was less reliable than lightness and chroma, which was more pronounced visually than electronically. The smallest detectable color difference varied among the four methods used, and was most favorable in the electronic 2D system. Comparing the methods, the agreement between the 2D and 3D system in terms of ΔE was not good. The reliability of the visual and electronic method was essentially the same in the 2D and 3D systems; this comparability is fair to good. CLINICAL RELEVANCE: The 3D system may confuse human raters and even electronic devices. The 2D system is the simple and best choice.

Differentiated analysis of orthodontic tooth movement in rats with an improved rat model and three-dimensional imaging.

Rat models currently available for analysis of orthodontic tooth movement often lack differentiated, reliable and precise measurement systems allowing researchers to separately investigate the individual contribution of tooth tipping, body translation and root torque to overall displacement. Many previously proposed models have serious limitations such as the rather inaccurate analysis of the effects of orthodontic forces on rat incisors. We therefore developed a differentiated measurement system that was used within a rat model with the aim of overcoming the limitations of previous studies. The first left upper molar and the upper incisors of 24 male Wistar rats were subjected to a constant orthodontic force of 0.25 N by means of a NiTi closed coil spring for up to four weeks. The extent of the various types of tooth movement was measured optometrically with a CCD microscope camera and cephalometrically by means of cone beam computed tomography (CBCT). Both types of measurement proved to be reliable for consecutive measurements and the significant tooth movement induced had no harmful effects on the animals. Movement kinetics corresponded to known physiological processes and tipping and body movement equally contributed to the tooth displacement. The upper incisors of the rats were significantly deformed and their natural eruption was effectively halted. The results showed that our proposed measurement systems used within a rat model resolved most of the inadequacies of previous studies. They are reliable, precise and physiological tools for the differentiated analysis of orthodontic tooth movement while simultaneously preserving animal welfare.

Correlation of condylar kinematics in children with gender, facial type and weight.

OBJECTIVE: The aim of the study has been to describe the normal range of mandibular movements and condylar kinematics in children as well as to test the null hypothesis that these variables are not associated with gender, facial type and weight. MATERIALS AND METHODS: The sample was comprised of 92 healthy children (7.2-10.6 years old) and 40 adult controls (18-34.7 years old). Examinations included the maximal mouth opening capacity and laterotrusion to the right and to the left. The condylar path inclination angle was calculated at 3mm and 5mm protrusion of the mandible. Kinematic variables were registered using the ultrasonic JMA system. RESULTS: Maximal mouth opening capacity averaged 46.73 mm for the children and 53.53 mm for the adults. The mean values of the lateral movements were 9.36 mm to the right and 9.62 mm to the left for the boys, and 9.91 mm and 9.68 mm for the girls, respectively. Mean condylar path inclination in the children was 36.5° (right) and 36.2° (left) at 3mm of protrusive movement, and 34.3° (right) and 34.0° (left) at 5mm of protrusive movement. Associations of the kinematic variables with gender, weight, or facial type were insignificant. CONCLUSION: Younger school children have not yet reached the maximum mouth-opening capacity. Correlation analysis suggests some weak, but insignificant associations of gender, facial type and weight with mouth opening, laterotrusion and the condylar path inclination angle. The null hypothesis was not rejected.

Alveolar ridge sockets preservation with bone grafting--review.

INTRODUCTION: Alveolar bone seems to play a key role in providing support to the teeth, which are anchored to the bone by desmodontal fibers. The progressive alveolar bone resorption process occurs due to a loss of anatomic, biologic and mechanical factors. Mechanical stimulation of alveolar bone during mastication is crucial in keeping the teeth and underlying bone healthy. Tooth extraction leads to typical bone deficiency of ridge width and height of alveolar crest and reduces the possibility of placing screw titanium implants. When tooth extraction is necessary, trauma should be minimized during the procedure and bone preservation should receive careful attention. The literature has shown that early bone loss can be significantly reduced by socket grafting. The process of socket grafting requires an understanding of wound healing and an appreciation of the biological properties of the products available for socket grafting. Augmentative measures may, thus, be required to guarantee optimal prosthetic replacement of the lost tissue. Success or failure of augmentation procedures is dependent on revascularization and remodelling of the grafted bone into a vital, load bearing bone. In contrast to a visible three-dimensional change, the concept of remodelling refers to the internal turnover of bone, which is a coupled process where osteoclastic resorption and osteoblastic formation are more or less balanced. To restore alveolar bone loss and support efficient placement of dental implants, many different bone substitute such as autografts, allografts, xenografts, synthetic biomaterials and osteoactive agents have been proposed. In order to avoid harvesting an autograft, and thereby eliminating additional surgical procedures and risks, bone grafting materials and substitutes are alternative filler materials to be used for ridge augmentation. PURPOSE: To present a literature review about biomaterials applicable in alveolar ridge sockets preservation to future implants insertion. CONCLUSION: The maintenance of the dental alveolar bone after extraction depend on the attentive surgery procedure and the use of materials capable to maintain the prior space and be helpful in bone tissue healing.

In vivo study of apoptosis as a creative agent of embryonic development of the primary nasal duct in rats.

INTRODUCTION: The first embryonic part of the nasal cavity is the primary nasal duct, beginning with the olfactory placode and ending with the oronasal membrane. Aim of this study was to investigate the cellular processes (apoptosis, proliferation) being responsible for development and opening of the primary nasal duct. MATERIAL AND METHODS: In this study developmental processes in at least three regions of the primary nasal duct (opening, middle, end) were examined by sectioning 38 rat fetuses on day 13.5 after conception. Apoptotic cells were detected by active caspase-3 antibodies and proliferating cells were examined by Ki-67 antibodies. RESULTS: Multiple apoptotic events were diagnosed on the basis and proliferative cells on the top of this duct. CONCLUSION: Apoptosis and proliferation play an important role in the process of opening the bottom of the primary nasal duct and for development of the nasal septum, philtrum as well as the primary palate. Mesenchymal proliferation seems to play a minor role in the process of opening the primary nasal duct.

Apoptosis as a creative agent of embryonic development of bucca, mentum and nasolacrimal duct. An in vivo study in rats.

INTRODUCTION: For embryonal facial development several fusion processes between different facial prominences are necessary. If fusion fails to appear, various facial clefts may occur, known as median (e.g. lower median cleft lip), oblique (e.g. open nasolacrimal duct) or lateral facial clefts (macrostomia, lateral cleft). MATERIAL AND METHODS: The development of 3 different facial regions (bucca, mentum, and nasolacrimal duct) was examined in rats using serial histological sections on day 13.5 after conception. Common procedures were used (staining for active caspase-3 and for Ki-67) for histological assessment about the role of apoptotic and proliferative processes in the fusion zones of buccal, mental and nasolacrimal areas. RESULTS: Multiple apoptotic events were detected in epithelial cells of the respective regions, the proliferative centers were located in the mesenchymal surroundings of fusion zones. CONCLUSION: A substantial precondition for fusion of facial prominences are proliferative and apoptotic processes in epithelial and mesenchymal cells. Apoptosis contributes to the development of bucca, mentum and the nasolacrimal duct. Absence of apoptoses may be responsible for facial clefts.

Cartilaginous septum deviation in children with cleft lip, alveolus and palate--an MRI analysis.

INTRODUCTION: This study aimed to investigate by MRI examination the degree of deviation of the cartilaginous septum in relation to cleft size in patients with cleft lip, alveolus and palate. MATERIAL AND METHODS: Six children with cleft lip, alveolus and palate at age 5-20 days were examined with a 1.0 Tesla scanner using a head coil. The following parameters were evaluated: maximal cleft size (millimeter) and degree of the nasal septum deviation from the median-sagittal plane (degrees). RESULTS: Two children with bilateral clefts had no deviation; 3 children with unilateral (left-sided) cleft had a deviation to the right and 1 patient with a unilateral right-sided cleft a deviation to the left side. In all 4 patients, the degree of the nasal septum deviation increased with cleft size. CONCLUSION: Cartilaginous nasal septum deviation was noticed only in patients with unilateral cleft lip and palate toward the non-cleft side and was greater with increasing cleft sizes.

Initial findings on teratological and developmental relationships and differences between neural tube defects and facial clefting. First experimental results.

Unless genetically caused, the occurrence of neural tube defects and clefts of the lip, alveolus and palate are not associated. These malformations do, however, share some common causes, one of which is folic acid deficiency. Nevertheless, it is not known why a neural tube defect resulting from folic acid deficiency does not occur in combination with facial clefts. Based on animal experiments and a review of the literature, it is assumed that other factors--such as vitamin B6 deficiency--though clinically not diagnosed, can more often cause malformations.