The Relationships Between Perioral Musculature, Natural Tooth Position, and the Supporting Periodontium

Abstract

Precision medicine aims to prevent and treat disease using patient-specific data, including genetic and environmental factors. While precision medicine continues to improve the quality of care for patients worldwide, this customized approach to care is beginning to emerge within dentistry. The advancement of three-dimensional imaging and printing technology, artificial intelligence, and smart appliances have created a platform for precision orthodontics. However, there is still a lack of data in the literature regarding the effects of intrinsic patient forces on the outcome and stability of orthodontic treatment. This study aimed to explore the relationships between the natural position of teeth, the condition of their supporting periodontal tissue, and contraction forces of adjacent perioral musculature. There were three null hypotheses in this study:

there is no direct relationship between increased lip force surrounding the dentition and intercanine width, 2) there is no direct relationship between increased tongue force surrounding the dentition and incisor position, and 3) there is no direct relationship between the position of the mandibular incisors and the health of their supporting periodontium. The position and angulation of incisors for orthodontically untreated adult patients (N= 24, average age 24.5) were measured on lateral cephalograms and compared to maximum contraction forces of lip and tongue muscles obtained using a novel intraoral pressure gauge (TongueometerTM, E2 Scientific). Ultrasound images of the four mandibular incisors were also captured to examine the height of their facial alveolar bone. The null hypotheses were accepted. We could not identify any significant correlation between the maximum contraction force of the lip or tongue musculature on the inclination or sagittal positioning of the incisors. However, increased intercanine widths were positively correlated with increased lip muscle contraction strength and incisor-mandibular plane angle measurements were negatively correlated with the facial bone height of mandibular incisors. These preliminary findings may add further support to the existing literature that claims 1) increasing intercanine widths during orthodontic treatment may result in poor stability due to increased lip forces, and 2) individuals with increased incisor-mandibular plane angles lack hard periodontal support and are at greater risk for periodontal tissue damage. Future studies with an increased numbers of participants are necessary to identify other components of the dental equilibrium, such as resting perioral tissue pressures.