Comparison of clinical and electromyographic rest vertical dimensions in dolichofacial and brachyfacial young adults: A cross-sectional study

Development of craniometry-based predictive model to determine occlusal vertical dimension by using the eye-ear distance in a French population

STATEMENT OF PROBLEM

Techniques for determining occlusal vertical dimension (OVD) have limitations, including the lack of reproducibility or invasiveness. Recently, a craniometry-based predictive model comparing OVD with eye-ear distance (EED) was developed in Chile. However, this study included a specific population and excluded patients with a history of orthodontics. For verification, studies on other populations are required.

PURPOSE

The purpose of this clinical study was to follow the previously described protocol to obtain an equation for determining OVD in a French cohort (mostly White with an orthodontic history).

MATERIAL AND METHODS

Dentate adults with a stable occlusion and no known maxillofacial, otolaryngeal, or temporomandibular problems were included in this study. Demographic information, including participant age, sex, and history of orthodontic treatment, was collected. Facial height and width were measured with digital calipers, and the left EED and OVD were recorded with a craniometer. The facial index was calculated to classify participants into euryprosopic, mesoprosopic, or leptoprosopic types.

RESULTS

Of the 300 included participants (28 ±11 years), 60% were women, and 67% reported a history of orthodontic treatment. Euryprosopic represented 17% of participants, mesoprosopic 48%, and leptoposopic 35%. A positive correlation was found between the left EED and OVD in all facial types, but it was more important in women. The following equation was obtained: OVD=44.58+(0.45×left EED)+sex (women=-4.57; men=0)+facial type (leptoprosopic=0; mesoprosopic=-3.35; euryprosopic=-7.27).

CONCLUSIONS

The occlusal vertical dimension is correlated with sex, left EED, and facial type. This straightforward method can be applied in conjunction with other techniques to determine the OVD in the French population.

[The value of an occlusal adjustment: why?, how?, and when? case report]

The aim of optimal dentistry is to stabilise the stomatognathic system (teeth, periodontium, muscles and temporomandibular joint). All of these must work in harmony, as together they provide optimal care from diagnosis through planning to treatment. However, many clinicians currently give little importance to the identification of premature contacts and/or interferences prior to any dental treatment, which should be taken into account to provide improved stability in mandibular closure, correct anterior and canine guidance in mandibular movements.This clinical case describes the treatment of a patient with a diagnosis of functional occlusal disorder due to premature contact, whose treatment consisted of an occlusal adjustment by selective wear, following the technique described by the author Klineberg, with the aim of preserving the dental structure as much as possible while maintaining control during the occlusal adjustment and returning the greatest number of symmetrical and pointed contacts.

Mandibular ramus height and condyle distance asymmetries in individuals with different facial growth patterns: a cone-beam computed tomography study

PURPOSE

This study aimed to quantify mandibular ramus height and condylar distances asymmetry indexes in adult patients with different vertical facial growth pattern using Cone Beam computed tomography (CBCT).

METHODS

An observational cross-sectional study was conducted by using CBCT of 159 patients (mean age 26.36 ± 5.32 years). Vistadent 3D^® software was used to determine the facial pattern in 3 groups (N = 53): hypodivergent, normodivergent and hyperdivergent-by Ricketts VERT index. Mandibular ramus height and the condylar linear distance in relation to the median sagittal plane were evaluated. The asymmetry index was calculated considering the right and left sides. Data were analyzed by generalized linear models and Tukey post-hoc test (α = 0.05).

RESULTS

Significantly lower values were found for the left and right mandibular ramus height in the hyperdivergent skeletal pattern (P < 0.05). There was no statistically significant difference for condylar and intercondylar distances among the facial groups (P > 0.05). Asymmetry indexes (mandibular ramus height and condylar distance) were similar, and no statistically significant differences were found among the skeletal patterns. In most subjects, the severity of mandibular ramus height asymmetry varied from light to not clinically significant independently of the facial type.

CONCLUSION

The findings suggest that vertical facial growth pattern not affected the asymmetry index of mandibular ramus height and the intercondylar distance. The results also demonstrated significantly shorter mandibular ramus height for the hyperdivergent skeletal pattern individuals.

A craniometry-based predictive model to determine occlusal vertical dimension

STATEMENT OF PROBLEM

Craniometry is a method of determining the occlusal vertical dimension (OVD); the current prediction models do not consider factors such as facial type and sex or normalizing the OVD by using 1 main variable.

PURPOSE

The purpose of this clinical study was to determine whether sex, facial type, and age can influence the creation of a predictive model by using the right or left eye-to-ear distance to determine the OVD in dentate and edentate individuals.

MATERIAL AND METHODS

Healthy individuals (N=385) (238 women, 147 men) aged between 18 and 50 years were classified according to sex, age, and facial type. A single operator recorded all distances in millimeters between the anatomic landmarks proposed by Knebleman (nose-to-chin and right and left eye-to-ear distances) by using a computer numerical control (CNC) machined aluminum anatomic gauge. Measurements were converted into z-scores to determine abnormal values (±3 standard deviations criteria). The Pearson correlation coefficient was calculated for each facial type and for the entire sample between nose-to-chin and the right and left eye-to-ear distances. Multiple regression analysis was performed to establish the dependence of the measured variables on the OVD and the development of a further predictive model (α=.05).

RESULTS

According to the z-scores of the measured distances, 4 participants were discarded, leaving a final sample of 381 participants (237 women, 144 men; 115 leptoprosopic, 164 mesoprosopic, 102 euryprosopic). The left eye-to-ear distance showed a better correlation with the nose-to-chin distance (leptoprosopic r=0.54, mesoprosopic r=0.60, euryprosopic r=0.55, total sample=0.56) than the right eye-to-ear distance (leptoprosopic r=0.48, mesoprosopic r=0.56, euryprosopic r=0.54, total sample=0.51). Multiple regression analysis revealed that age was not a predictive variable (P=.57), that OVD depended on sex (P<.001) and facial type (P<.01), and that women had shorter OVD than men, as well as more euryprosopic faces than leptoprosopic faces. Using these relationships, the following equation to determine OVD was constructed as a model: OVD=42.17+(0.46×left eye-to-ear distance)+sex (women=-3.38, men=0)+facial type (leptoprosopic=0, mesoprosopic=-1.19, euryprosopic=-2.19).

CONCLUSIONS

OVD depends on facial type and sex, both of which are craniometric variables. This study proposed a baseline method of determining OVD by using the left eye-to-ear distance as an initial reference that involves a straightforward mathematical calculation.