Posture Assessment in Dentistry for Different Visual Aids Using 2D Markers.

Attention and awareness towards musculoskeletal disorders (MSDs) in the dental profession has increased considerably in the last few years. From recent literature reviews, it appears that the prevalence of MSDs in dentists concerns between 64 and 93%. In our clinical trial, we have assessed the dentist posture during the extraction of 90 third lower molars depending on whether the operator performs the intervention by the use of the operating microscope, surgical loupes, or with the naked eye. In particular, we analyzed the evolution of the body posture during different interventions evaluating the impact of visual aids with respect to naked eye interventions. The presented posture assessment approach is based on 3D acquisitions of the upper body, based on planar markers, which allows us to discriminate spatial displacements up to 2 mm in translation and 1 degree in rotation. We found a significant reduction of neck bending in interventions using visual aids, in particular for those performed with the microscope. We further investigated the impact of different postures on MSD risk using a widely adopted evaluation tool for ergonomic investigations of workplaces, named (RULA) Rapid Upper Limb Assessment. The analysis performed in this clinical trial is based on a 3D marker tracker that is able to follow a surgeon's upper limbs during interventions. The method highlighted pros and cons of different approaches.

Influence of oscillating and rotary cutting instruments with electric and turbine handpieces on tooth preparation surfaces.

STATEMENT OF THE PROBLEM: Rotary and nonrotary cutting instruments are used to produce specific characteristics on the axial and marginal surfaces of teeth being prepared for fixed restorations. Oscillating instruments have been suggested for tooth preparation, but no comparative surface roughness data are available. PURPOSE: To compare the surface roughness of simulated tooth preparations produced by oscillating instruments versus rotary cutting instruments with turbine and electric handpieces. MATERIAL AND METHODS: Different grit rotary cutting instruments were used to prepare Macor specimens (n=36) with 2 handpieces. The surface roughness obtained with rotary cutting instruments was compared with that produced by oscillating cutting instruments. The instruments used were as follows: coarse, then fine-grit rotary cutting instruments with a turbine (group CFT) or an electric handpiece (group CFE); coarse, then medium-grit rotary cutting instruments with a turbine (group CMT) or an electric handpiece (group CME); coarse-grit rotary cutting instruments with a turbine handpiece and oscillating instruments at a low-power (group CSL) or high-power setting (group CSH). A custom testing apparatus was used to test all instruments. The average roughness was measured for each specimen with a 3-dimensional optical surface profiler and compared with 1-way ANOVA and the Tukey honestly significant difference post hoc test for multiple comparisons (α=.05). RESULTS: Oscillating cutting instruments produced surface roughness values similar to those produced by similar grit rotary cutting instruments with a turbine handpiece. The electric handpiece produced smoother surfaces than the turbine regardless of rotary cutting instrument grit. CONCLUSION: Rotary cutting instruments with electric handpieces produced the smoothest surface, whereas the same instruments used with a turbine and oscillating instruments achieved similar surface roughness.

Accuracy of a new photometric jaw tracking system in the frontal plane at different recording distances: An in-vitro study.

OBJECTIVES: To evaluate the accuracy of a new photometric jaw tracking system (JTS) in recording linear vertical movements in the frontal plane at different distances. METHODS: A mandibular plaster cast of a patient was placed on a simulation machine capable of linear movements along two spatial axes. Cyclops JTS (Itaka) was adapted to the plaster cast, while the head frame was attached to the simulation machine. The latter performed five linear movements from 20 to 40 mm in the y-axis; each movement was repeated five times at five different recording distance (380 to 420 mm). The recorded movements were measured and compared with those obtained with a laser Doppler vibrometer (LDV) for accuracy analysis. Data were statistically processed (α = 0.05). RESULTS: No statistically significant differences were found between Cyclops and LDV measurements on the y- and z-axes (p = 0.5). Changes in linear vertical motion and distance positions did not affect the accuracy, which remained relatively constant with similar trends and values less than 1 % for each parameter variation. The best condition observed was linear vertical movement of 30 mm at 420 mm (0.010 ± 0.023 mm). CONCLUSIONS: Cyclops has proven to be an accurate JTS in recording linear vertical movements in the frontal plane at different recording distances. For optimal recordings, the scanner should be placed as close as possible to the markers; excessive vertical movements decreased the accuracy. However, this study has limitations and requires in-vivo confirmations. CLINICAL SIGNIFICANCE: The tested JTS proved accurate in recording linear vertical movements in the frontal plane. However, given the limitations of the study, further investigation under real conditions is needed to support prosthetic and gnathological rehabilitations.

The Smile Esthetic Index (SEI): A method to measure the esthetics of the smile. An intra-rater and inter-rater agreement study.

PURPOSE: To propose a method to measure the esthetics of the smile and to report its validation by means of an intra-rater and inter-rater agreement analysis. MATERIALS AND METHODS: Ten variables were chosen as determinants for the esthetics of a smile: smile line and facial midline, tooth alignment, tooth deformity, tooth dischromy, gingival dischromy, gingival recession, gingival excess, gingival scars and diastema/missing papillae. One examiner consecutively selected seventy smile pictures, which were in the frontal view. Ten examiners, with different levels of clinical experience and specialties, applied the proposed assessment method twice on the selected pictures, independently and blindly. Intraclass correlation coefficient (ICC) and Fleiss' kappa) statistics were performed to analyse the intra-rater and inter-rater agreement. RESULTS: Considering the cumulative assessment of the Smile Esthetic Index (SEI), the ICC value for the inter-rater agreement of the 10 examiners was 0.62 (95% CI: 0.51 to 0.72), representing a substantial agreement. Intra-rater agreement ranged from 0.86 to 0.99. Inter-rater agreement (Fleiss' kappa statistics) calculated for each variable ranged from 0.17 to 0.75. CONCLUSION: The SEI was a reproducible method, to assess the esthetic component of the smile, useful for the diagnostic phase and for setting appropriate treatment plans.

Immediate loading of full-arch fixed prostheses supported by axial and tilted implants for the treatment of edentulous atrophic mandibles.

OBJECTIVES: This study aimed to evaluate the long-term prognosis of immediately loaded fixed full prostheses for the treatment of edentulous patients with extreme bone atrophy in the posterior mandibular region. MATERIAL AND METHODS: Twenty-four edentulous patients with atrophic posterior mandibles were treated by means of a complete prosthesis sustained by both axial and tilted fixtures. The insertion of tilted implants was carefully planned by means of computed tomography scan analysis and measuring width and height of residual bone. Implant type, length, and diameter were chosen, as well as implant angulation, according to the All-on-Four protocol and avoiding the course of the mandibular nerve. The prosthesis was delivered no later than 2 days after implant surgery. Implant survival and prosthesis success were assessed clinically and radiographically up to 42 months of follow-up. Measurement of peri-implant bone loss was based on periapical radiographs after 12 months of loading. RESULTS: All implants survived and all prostheses were successful at the time of this study reporting. The mean follow-up was 30.1 months with a range of 14 to 44 months. The average peri-implant bone loss was 0.85 mm after 12 months (0.8 mm for tilted implants and 0.9 mm for axial implants). No significant difference in marginal bone loss was observed between axial and tilted implants. CONCLUSIONS: The immediate rehabilitation of patients with extreme atrophic mandibles can be successful with careful planning and particular attention during the surgical placement of the implants, as shown by the excellent outcomes of the present study.