Despite many advances in dentistry, no objective and quantitative method is available to evaluate gingival shape. The surface curvature of the optical scans represents an unexploited possibility. The ...present study aimed to test surface curvature estimation of intraoral scans for objective evaluation of gingival shape.
The method consists of four main steps, i.e., optical scanning, surface curvature estimation, region of interest (ROI) definition, and gingival shape analysis. Six different curvature measures and three different diameters were tested for surface curvature estimation on central (n = 78) and interdental ROI (n = 88) of patients with advanced periodontitis to quantify gingiva with a novel gingival shape parameter (GS). The reproducibility was evaluated by repeating the method on two consecutive intraoral scans obtained with a scan-rescan process of the same patient at the same time point (n = 8).
Minimum and mean curvature measures computed at 2 mm diameter seem optimal GS to quantify shape at central and interdental ROI, respectively. The mean (and standard deviation) of the GS was 0.33 ± 0.07 and 0.19 ± 0.09 for central ROI using minimum, and interdental ROI using mean curvature measure, respectively, computed at a diameter of 2 mm. The method's reproducibility evaluated on scan-rescan models for the above-mentioned ROI and curvature measures was 0.02 and 0.01, respectively.
Surface curvature estimation of the intraoral optical scans presents a precise and highly reproducible method for the objective gingival shape quantification enabling the detection of subtle changes. A careful selection of parameters for surface curvature estimation and curvature measures is required.
The aim of this study was to test the clinical application of an intraoral scanner for serial evaluation of orthodontic tooth movement. The maxillary dentitions of eight patients with fixed ...orthodontic appliances were scanned using an intraoral scanner at the beginning of treatment (T0), and at 1 month (T1), 2 months (T2), 3 months (T3), and 4 months (T4) after T0. The serial digital models were superimposed on the palatal surface as a reference area, and the linear and angular changes of the central incisors, canines, and first molars were evaluated. The intraclass correlation coefficient and method errors showed that this method was clinically acceptable. Various types of orthodontic tooth movements, including minute movements, could be observed every month. The intraoral scanner and digital superimposition technique enabled the serial evaluation of orthodontic tooth movement without taking serial impressions and/or acquiring radiographs.
Objective
To evaluate whether dental arch relationships at 6 years of age can categorize treatment outcome and predict later need for orthognathic surgery in children with unilateral cleft lip and ...palate (UCLP).
Setting and sample population
A retrospective longitudinal single‐centre study. The study sample comprised 70 consecutive non‐syndromic children (47 boys) with complete UCLP operated on by pushback techniques during 1981‐1989 and followed until early adulthood in the same cleft centre.
Materials and methods
Dental casts and maxillomandibular relationships were assessed before orthodontic treatment and secondary alveolar bone grafting at mean age 6.1 years (range 5.6‐6.8) using the 5‐year‐olds' index and lateral cephalograms. The need for orthognathic surgery was retrieved from patient files. Student's t test, Pearson's correlation, and Kappa statistics were used in statistical analyses.
Results
Orthognathic surgery frequency was 41% (29/70). Those needing orthognathic surgery comprised all 3 patients with an index score of 5 (very poor), 14 of 17 (82%) scoring 4 (poor), 10 of 26 (38%) scoring 3 (fair), and 2 of 19 (11%) scoring 2 (good). Of the five patients with index score 1 (excellent), none needed osteotomies. The mean index score was 2.9. The score was significantly better in those without orthognathic surgery (2.4 versus 3.6). A significant negative correlation existed between the 5‐year‐olds' index and cephalometric angles ANB and anb.
Conclusion
The use of 5‐year‐olds' index may help to predict treatment outcome and the clinical need for orthognathic surgery especially in patients with the lowest and highest index scores.
Objective: This study aimed to compare the maxillary and mandibular transverse dental arch widths and buccolingual inclinations of the molar teeth in patients with and without bilateral posterior ...crossbite (BPC) divided into different age groups. Methods: The study included dental models from 120 patients (age: 12-18 years), including 60 with BPC (32 boys and 28 girls) and 60 without BPC (controls; 30 boys and 30 girls), who were divided into three age groups (12-14, 14-16, and 16-18 years). The centroid and lingual transverse arch widths, dental arch perimeters, dental arch depths, and buccolingual angulation of the molar teeth in the maxillary and mandibular regions were evaluated using scanned three-dimensional dental models. Results: Dental arch parameters and buccolingual molar angulation did not significantly differ between the different age groups in either the patients with BPC or the controls (p>0.05). However, several dental arch width parameters differed significantly between sexes in both groups, with higher values in boys than in girls (p<0.05). The difference in the upper and lower molar buccolingual angulation between patients with BPC and controls was greater at the age of 16-18 years than the age of 12-14 years (p<0.05). Conclusion: Patients with BPC have smaller maxillary dental arch widths and larger mandibular intermolar widths than those without BPC. The difference in the molar buccolingual angulation between them increases with advancing age. Keywords: Posterior crossbite, dental model analysis, buccolingual angulation
The purpose of this study was to evaluate the accuracy of a dental model fabricated using the CAD/CAM milling method and the 3D printing method. Materials and Method: This study was conducted in ...sequence of the digitization of the master model using an intraoral scanner, the manufacturing of working models (milling model, Multi-jet printing model and Color-jet printing model) by using the scan data of the master model, the digitization of the working model by using a laboratory scanner, the superimposition of the digital data of the master model and working models using inspection software, and 3-dimensional analysis. Ten measurements per group were done by one practitioner. One-way ANOVA and Tukey’s post-hoc test were performed to compare the difference between the three groups. Results: The overall difference in models caused by the manufacturing method was measured as 73.05μm±9.64μm, 84.52μm±4.78μm, and 96.05μm±5.43μm in the milling group, Multi-jet printing group and Color-jet printing group, respectively. The difference according to the shape of the teeth, the abutment teeth among the three parts was recorded with the lowest values as 19.18±2.08μm, 77.10±7.48μm, and 56.63±4.58μm. Conclusions: Dental models manufactured by the CAD/CAM milling method presented superior accuracy over the models manufactured by the 3D printing method. Therefore, the use of optimized CAD software and appropriate materials is crucial for the fabrication accuracy of dental models.
A translational ex vivo perfusion-based mandibular pig model was developed as an alternative to animal experiments, for initial assessment of biomaterials in dental and maxillofacial surgery and ...training. This study aimed to assess the face and content validity of the novel perfusion-based model.
Cadaveric porcine heads were connected to an organ assist perfusion device for blood circulation and tissue oxygenation. Dental professionals and dental trainees performed a surgical procedure on the mandibula resembling a submandibular extraoral incision to create bone defects. The bone defects were filled and covered with a commercial barrier membrane. All participants completed a questionnaire using a 5-point Likert scale to assess the face and content validity of the model. Validation data between the two groups of participants were compared with Mann-Whitney U test.
Ten dental professionals and seven trainees evaluated the model for face and content validity. Participants reported model realism, with a mean face validity score of 3.9 ± 1.0 and a content validity of 4.1 ± 0.8. No significant differences were found for overall face and content validity between experts and trainees.
We established face and content validity in a novel perfusion-based mandibular surgery model. This model can be used as an alternative for animal studies evaluating new biomaterials and related dental and maxillofacial surgical procedural training.
The aim of this study was to appraise a recently developed preparedness model for the provision of oral health care during a threat such as the COVID-19 pandemic from the perspectives of oral health ...care providers, administrators/staff, and patients.
An exploratory qualitative inquiry via at-a-distance semi-structured interviews and group discussions engaged a purposefully selected sample of oral health care workers and patients in British Columbia (BC), Canada. Participants were asked to appraise a preparedness model by considering how to prepare for oral care during a pandemic, while answering open-ended questions about the model content and visual presentation. Interviews and group discussions occurred between April 2020 and January 2021, were audio recorded, and transcribed verbatim. An inductive coding process was used to identify themes, subthemes, and categories of information until saturation was achieved.
Seventy-four participants, including 19 dentists, 15 dental hygienists, 10 certified dental assistants, 9 administrators, and 21 patients, suggested modifications to the recently developed preparedness model. Individual interviews (41 participants) and group discussions (33 participants in groups ranging from 2 to 9 attendees each) lasted for an average of 53 min. Eighty-four hours of audio recordings led to more than 1110 single-spaced pages of transcripts. The thematic analysis identified 82 codes, 12 categories, and four main themes: life-long learning, critical thinking, personal and professional risk, and patient-centred care. These themes were understood within provider characteristics and social and environmental contexts. Participants highlighted the need for the model to focus on information and communication, developing awareness and understanding, inferring risks, and performing oral health care during a threat such as a pandemic or disease outbreak. A modified portrayal of the model was suggested to better represent participants' perspectives.
A recently developed preparedness model for the provision of dental care during an unfolding threat like the COVID-19 pandemic was appraised and modified by oral health care workers. Future studies are warranted to evaluate the modified model for use in the event of another unfolding threat collaboratively with providers, patients and stakeholders.
This study aimed to assess the reliability of two intraoral surface scanners for the representation of the alveolar process in vivo. Complete maxillary scans (CS 3600, Carestream and TRIOS 3, 3Shape) ...were repeatedly obtained from 13 fully dentate individuals. Scanner precision and agreement were tested using 3D surface superimpositions on the following reference areas: the buccal front teeth area, the entire dental arch, the entire alveolar process, or single teeth by applying an iterative closest point algorithm. Following each superimposition, the mean absolute distance (MAD) between predefined 3D model surfaces was calculated. Outcomes were analyzed through non-parametric statistics and the visualization of color-coded distance maps. When superimpositions were performed on the alveolar process, the median scanner precision was below 0.05 mm, with statistically significant but negligible differences between scanners. The agreement between the scanners was approximately 0.06 mm. When single-tooth superimpositions were used to assess the precision of adjacent alveolar soft-tissue surfaces, the median error was 0.028 mm, and there was higher agreement between the scanners. The in vivo reliability of the intraoral scanners in the alveolar surface area was high overall. Single-tooth superimpositions should be preferred for the optimal assessment of neighboring alveolar surface areas relative to the dentition.
The surgery-first approach (SFA) is conducted to decrease the difficulty and duration of orthodontic treatment by correcting the skeletal discrepancy at the initial stage of treatment. However, the ...indication of the SFA has not been well defined yet. This study explored the dental occlusion characteristics for treatment decision-making regarding the SFA. A total of 200 skeletal Class III patients were consecutively collected and divided into two groups: the orthodontic-first approach (OFA) group and the SFA group. The pretreatment digital dental models and lateral cephalograms were measured. Logistic regression was completed and receiver operating characteristic (ROC) curves were obtained to predict the probability of the SFA. Results showed that the ROC model with L1-MP, upper and lower arch length discrepancy, overbite, and asymmetric tooth number as influencing factors revealed that the sensitivity and specificity for determining SFA were 83.0% and 65.0%, respectively; the accuracy of prediction was 75.0%. In conclusion, our findings indicate that the six measurements from digital dental models and lateral cephalograms can be effectively applied in treatment decision-making for the SFA with satisfactory accuracy.
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