Are dental measurements taken on plaster casts comparable to those taken from CBCT images and laser scanned surfaces?

Introduction: Intraoral scanning techniques, laser scans and cone-beam computed tomography (CBCT) are becoming widely diffused in dental practice. These instruments can replace dental plaster casts with digital models; recent investigations have found that measurements taken on digital models do not differ clinically from those obtained on CBCT scans and physical models, but only intra-examiner reliability has been assessed. In the current study we tested both intra- and inter-examiner variations, together with intertechniques reliability. Methodology: Data from six adult subjects were retrospectively obtained. Twelve dental distances were measured on dental plaster casts using a digital calliper; on digital 3D CBCT images using inVivoDental software (Anatomage, San Jose, CA); and on laser scanned surfaces using Mirror Vectra Software (Canfield Scientific, Fairfield, NJ). Two different operators performed all measurements twice. Bland-Altman analysis, Kruskal-Wallis and Wilcoxon tests were used for comparisons. Results: The intra- and inter-operator biases range was 0-0.34 mm. The reproducibility range was 72-99%. The three different techniques gave very similar measurements, with biases between \ub10.1 mm. Reproducibility ranged between 90 and 100%; the best reproducibility coefficients were found between plaster and digital casts, and only three differences were larger than 0.5 mm. Calliper measurements slightly overestimated digital casts values. Only the mesiodistal distance of tooth 24 (p=0.002) was significantly different among techniques. Conclusion: Measurements on digital dental models and CBCT reconstructions of the dental arches seem clinically reliable as direct calliper measurements. The inter- and intra-operator reliabilities were acceptable, some more care may be needed for CBCT measurements

Masticatory behavior and chewing difficulties in young adults with temporomandibular disorders

BACKGROUND: Difficulties and limitations on masticatory function are among the main reasons why patients with temporomandibular disorder (TMD) seek care. OBJECTIVE: To evaluate the masticatory behaviour and perception of chewing difficulties in adults with mild TMD of recent onset, considering the presence of malocclusion. METHODS: Eighty-one young adults were divided into groups according to the presence of TMD and malocclusion: Non-TMD Normal Occlusion (n = 18), Non-TMD Malocclusion (n = 22), TMD Normal Occlusion (n = 18) and TMD Malocclusion (n = 23). TMD was assessed using the TMD Research Diagnostic Criteria and volunteers also answered questionnaires regarding their perception about jaw functional limitation and difficulty to chew foods of different textures. Masticatory and swallowing behaviours were assessed using the Orofacial Myofunctional Evaluation with Scores (OMES) protocol. Chewing time and chewing frequency taken to ingest the test-food were also obtained. Two-way-ANOVA was used to analyse the TMD, occlusion and TMD 7 occlusion interaction effects. RESULTS: Temporomandibular disorder effect was observed on vertical jaw mobility and jaw function limitation total scores, meaning that groups differed in the perception of opening limitation and mandibular limitation according to TMD status with a medium effect size. Also, more changes in chewing function (OMES-chewing score) and higher chewing frequency was observed in the presence of TMD (P < 0.05). Occlusion effect was only observed on OMES-swallowing score and no TMD 7 occlusion interaction effect was observed. CONCLUSION: Changes in chewing behaviour, frequency and perception of mandibular limitation was observed in the presence of TMD, pointing out the importance of functional evaluation when planning and establishing a treatment plan

An index for the evaluation of 3D masticatory cycles variability

A comprehensive index for the analysis of the inter- and intra-subject variability of the 3D masticatory cycles trajectories was introduced and assessed in a healthy group and in patients with temporomandibular disorders

Laser scanner versus stereophotogrammetry : a three-dimensional quantitative approach for morphological analysis of pubic aymphysis

The reconstruction of biological profile is a crucial step for personal identification of unknown decedents, both in forensic and archaeological context. At this purpose, determination of age at death is a very important issue. Among the skeletal regions used for estimating it, the analysis of pubic symphysis by Suchey-Brooks method remains the most reliable aging technique. In the last years, technologies involving 3D image acquisition have acquired a growing importance in anthropology and may provide a relevant help in diffusion and sharing of skeletal specimens. In particular, among all the new available instruments, laser scanners and stereophotogrammetric systems are particularly useful to obtain 3D reconstructions of the pubic symphyseal surface. Furthermore, the possibility to create digital models of these bony structures allows researchers to easily and fast share their datasets worldwide, avoiding any possible damage to the real sample. This study aims at verifying the technical reproducibility of 3D acquisitions, performed by laser scanner and stereophotogrammetry, as a preliminary study to possible assessment of differences in age at death estimation. Since accuracy and reproducibility of these two instruments have already been evaluated, the study aims at comparing them in order to verify if there are some differences on relevant measurements obtained from the analysis of the 24 commercial casts (by Diane France). These 24 symphyseal casts (12 female and 12 male) were scanned by a dental laser scanner (Dental Wings series 3, Dental Wings Inc., Montreal, Canada) and a stereophotogrammetric system (Vectra 3D, Canfield Scientific, Fairfield, NJ). For each sample two scans were performed by the same tool and some measurements (symphyseal surface length, symphyseal surface area and billowing area) were taken twice on digitized surfaces, by the same operator. The second assessment was performed 15 days after the first one. Repeatability of operator measurements on different scans was assessed by paired Student t-test, or Mann-Whitney test, depending on data distribution. Linear regression was performed as well. To compare the two instruments, Bland-Altman analysis was carried out for billowing measurements. Results show no significant difference (p>0.05) in identification of the same parameter on different scans through both instruments and no significant difference between billowing areas, measured through laser scanner or stereophotogrammetry. In conclusion, data suggest that both 3D image acquisition systems may provide a technically reliable reproduction of pubic symphysis. However, the technical reproduction of skeletal specimens does not mean that the 3D scans are suitable for age estimation, which remains, in anthropological practice, a morphological procedure and requires a specific experience of the operator. Further studies are required to validate the opportunity to use this approach for anthropological age at death estimation