Facially driven guided crown lengthening using a complete digital workflow: A dental technique

A facially driven digital guided crown lengthening method using the virtual smile design approach supplemented with a static 3-dimensional face scan that demonstrates the digital data of extraoral soft tissue is presented. The technique enables the practitioner to virtually design the new smile and surgically plan the crown lengthening procedure.

Preorthodontic functional long-term trial restoration of a worn dentition for optimizing outcomes: A clinical report

Orthodontic tooth movement is often required before restorative treatment to maximize the esthetic and functional outcomes. Diagnostic waxing is a crucial step before active treatment to validate the optimal tooth position for future restorations. In this clinical report, a bonded prototype of the diagnostic waxing was used to guide and facilitate orthodontic treatment with the definitive restorations mind. The orthodontic treatment created the required space between the teeth for the ceramic restorations, improved dental and facial features, and restored appropriate incisal guidance.

Comparison between stereophotogrammetric, digital, and conventional impression techniques in implant-supported fixed complete arch prostheses: An in vitro study

STATEMENT OF PROBLEM

Conventional impressions and digital intraoral scanning for implant-supported fixed complete arch prostheses still have many problems that influence accuracy. Although stereophotogrammetry may offer a reliable alternative to other techniques, it has seldom been investigated.

PURPOSE

The purpose of this in vitro study was to measure and compare the intraoral scan body deviations of the reference cast with the intraoral scan body distortions obtained by conventional, digital, and stereophotogrammetric techniques.

MATERIALS AND METHODS

An edentulous maxillary "all-on-four" cast was prepared with 2 straight and two 17-degree angled screw-retained abutments screwed on the implant. Three capture techniques were compared: the conventional impression technique (CI group) using impression plaster (IP), the digital intraoral scanning (DIS group) technique, and the stereophotogrammetry (SPG group) technique. A calibrated extraoral scanner was used to digitize the definitive cast to compare its intraoral scan body positions with those of the other techniques in terms of global angular distortion and 3D deviations of the whole scan body and flat angled surface alone by using an inspection and metrology software program and the best fit alignment technique. The Kolmogorov-Smirnov and Shapiro-Wilk tests showed normal distribution of the quantitative variables. Thus, the repeated measures analyses of variance followed by univariate analysis and Bonferroni multiple comparison tests were performed to analyze the data (α=.05).

RESULTS

Significant global angular discrepancies and 3D deviations of the whole scan body and flat angled surface were found among the CI, DI, and SPG groups for both trueness (P<.001) and precision (P<.001).

CONCLUSIONS

The stereophotogrammetry capture technique reported the highest accuracy in terms of trueness and precision for the intraoral scan bodies of all the techniques evaluated. However, at the flat angled surface region of the scan body, higher trueness was detected with the digital technique. Conventional impressions showed better trueness results than the digital ones, but the opposite was true of precision.

The Prevalence and Predicting Factors of Temporomandibular Disorders in COVID-19 Infection: A Cross-Sectional Study

Introduction

During the pandemic of coronavirus disease 2019 (COVID-19), an increase in temporomandibular disorders (TMDs) was noticed in infected patients. In the present study, we aimed to assess the prevalence of TMDs during COVID-19 infection and to evaluate associated factors.

Methods

An observational cross-sectional online survey was conducted in April and May 2021 in order to estimate the prevalence of TMDs in participants who were previously infected with COVID-19. A multivariable logistic regression model was carried out to explore predicting factors of TMDs during COVID-19 infection.

Results

In total, the prevalence of TMDs during the COVID-19 infection period among participants was 41.9%. High fever episodes (adjusted odds ratio {aOR}: 3.25), gastro-esophageal reflux (aOR: 2.56), and toothache (aOR: 3.83) during COVID-19 illness were found to be positive predictors of TMDs, while vitamin D deficiency was found to be a negative predictor (aOR: 0.28).

Conclusion

Our study has highlighted a relatively high prevalence of TMDs in COVID-19-infected patients that may conclude TMDs as a possible COVID-19 symptom. Further studies are warranted to confirm the association between TMDs and COVID-19 infection and thereupon include TMDs among the known symptoms of COVID-19.

Effect of implant scan body geometric modifications on the trueness and scanning time of complete arch intraoral implant digital scans: An in vitro study

STATEMENT OF PROBLEM

The effect of the surface geometry of implant scan bodies (ISBs) on the accuracy and scanning time of complete-arch implant digital scans remains uncertain.

PURPOSE

The purpose of this in vitro study was to evaluate whether geometric modifications on implant scan bodies (nonmodified, subtractively modified, and additively modified ISBs) affect the trueness and scanning time of complete-arch intraoral implant digital scans.

MATERIAL AND METHODS

A completely edentulous maxillary cast with 2 anterior parallel and two 17-degree posteriorly tilted implant abutment analogs was prepared. A digitized reference was created from this cast with polyetheretherketone (PEEK) (CARES Mono Scanbody for screw-retained abutment) ISBs by using a desktop scanner (E3). Three different groups were created: nonmodified (NM group), subtractively modified (SM group), and additively modified (AM group). For the NM group, no modifications were made to the ISBs. For the SM group, 4 round-shaped grooves were created on the buccal, lingual, mesial, and distal sides. For the AM group, PEEK beads were printed and cemented on the same areas of the ISB of the SM group. Fifteen consecutive scans were captured with an intraoral scanner (TRIOS 3) for each group, and the scanning time was recorded. By using a metrology software program, scans of each group were superimposed on the reference file to determine the 3D surface, linear, and angular position discrepancies of each ISB. Repeated-measures analyses of variance followed by univariate analysis and Bonferroni multiple comparison tests were performed to analyze the data (α=.05). To compare the mean time among groups, 1-way analysis of variance was performed followed by the Tukey post hoc tests.

RESULTS

Significant 3D surface, linear, and angular position discrepancies were found when measuring trueness among the NM, SM, and AM groups (P<.001). Discrepancies in 3D surface deviation were highest for the AM group (0.266 ±0.030 mm), and the lowest mean angular deviation values were for the SM group (0.993 ±0.062 degrees). However, the mean scanning time was not significantly different among the groups tested (P=.237).

CONCLUSIONS

For complete-arch intraoral implant digital scans, subtractive modifications on ISBs enhanced scanning trueness, while additive modifications on ISBs decreased scanning trueness. However, implant scan body geometric modifications did not affect scanning time.

Assessment of the golden proportion in natural facial esthetics: A systematic review

STATEMENT OF PROBLEM

Faces considered attractive tend to possess a general harmony; however, scientific studies on the quantitative basis of human facial attractiveness are still sparse. The golden proportion has been the most documented ratio, but the actual existence of codified facial ratios in facially attractive individuals remains unclear.

PURPOSE

The purpose of this systematic review was to evaluate the deviation from the golden proportion in the measurements of different natural vertical facial ratios.

MATERIAL AND METHODS

A comprehensive search of the electronic databases that included PubMed/MEDLINE, Web of Science, Embase, Scopus, Scopus Secondary documents, and the Cochrane Database of Systematic Reviews was conducted using the terms "golden proportion", "golden proportions", "golden ratio", "golden ratios", "golden number", "golden section", "divine proportion", "divine proportions", "divine ratio", "divine ratios", and "Fibonacci" in combination with 1 or more of the ensuing terms: "facial proportion", "facial proportions", "facial measurement", and "facial measurements". Deviation of the facial proportions from the golden proportions was further analyzed by using a 1-sample t test (α=.05).

RESULTS

The 1-sample test showed no significant difference among the means of each variable (P>.05), suggesting that the golden proportion is found in natural facial esthetics.

CONCLUSIONS

No significant association was found between the golden ratio and facial evaluation scores among all ethnicities. The measurements and proportions for facial balance in the study population showed that the participant's facial height proportions did not follow the golden proportion.

Evaluation of the golden proportion in the natural dentition: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Different proportions of tooth width ratios have been evaluated, and the golden proportion is the best known. Although the prevalence of the golden proportion has been evaluated in different ethnic groups and populations, a meta-analysis of these studies is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to investigate the existence and suitability of the golden proportion for tooth width ratios and to assess the prevalence of the golden proportion among populations.

MATERIAL AND METHODS

A systematic search based on the Patient, Intervention, Comparison, Outcome (PICO) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted in PubMed, Cochrane, Scopus, Web of Science, and Embase in January 2021 without any time limitations and included English and non-English-language articles. Additional studies were identified by searching the reference lists of the retrieved articles. Two reviewers independently performed the literature search and data extraction, selecting articles based on the inclusion and exclusion criteria. Eligible studies were selected based on the inclusion criteria, and quality assessments were conducted. Descriptive statistics were applied for a number of outcome measures. Using a meta-analysis software program, data extracted from each selected study were statistically combined by using weighted mean differences and 95% confidence intervals, and heterogeneity was calculated for each measurement.

RESULTS

A total of 566 articles were retrieved based on the keyword search. After the articles were assessed based on the inclusion and exclusion criteria, only 6 articles were included in the meta-analysis.

CONCLUSIONS

The outcomes of the review and analyses demonstrate that evidence supporting the existence of the golden proportion in natural smiles is lacking and that the existence of the golden proportion in dentistry is a myth and not a fact. However, the golden percentage theory can be applied with modified percentages that consider critical aspects of esthetic dentistry.