Effect of dental wear, stabilization appliance and anterior tooth reconstruction on mandibular movements during speech

Abstract

This study described changes in mandibular movements during pronunciation of /m/ and /s/ sounds in Portuguese, in patients presenting dental wear before and after appliance insertion and tooth reconstruction. Subjects were divided into a control group of dentate patients and an experimental group of patients with incisal tooth wear due to bruxism. A magnetic jaw tracking device measured the jaw opening, and translations to left and right sides of the mandible during pronunciation of phonemes. Evaluations were carried out 1 week and immediately before appliance insertion; 24 h, 7, 30 and 60 days after appliance insertion; and 1 week and 1 month after tooth reconstruction. Data were submitted to two-way ANOVA, Mann-Whitney and Friedman tests (p<0.05). Jaw opening was different (p<0.05) for both sounds in all periods. The anteroposterior amplitude for /s/ showed differences immediately before and 1 month after appliance insertion (p<0.05). Lateral amplitude for the right side showed differences between groups after appliance insertion for /s/, and 1 and 2 months after appliance insertion for the /m/ (p<0.05). Volunteers with anterior tooth wear had a wider opening movement, and the movements during speech of /m/ and /s/ sounds were not changed after appliance insertion and reconstruction of teeth.

Influence of Occlusal Splint on Mandibular Movements in Patients with Bruxism: a Comparative Pilot Study

“…In this study, before the beginning of the treatment, mandibular movements in subjects with bruxism averaged 43.69 mm for mouth opening, 8.28 mm for left laterotrusion, and 8.17 mm for right laterotrusion. The increase in all mandibular movements after splint treatment established in this study was confirmed in similar studies in asymptomatic subjects, as well as in subjects with bruxism ( 12 ) and TMD ( 20 , 21 ). In this study, the highest increase in mandibular movements was found for mouth opening, which is consistent with the research by Serrano et al ( 12 ) and Katyayana et al ( 20 ).…”

“…The increase in all mandibular movements after splint treatment established in this study was confirmed in similar studies in asymptomatic subjects, as well as in subjects with bruxism ( 12 ) and TMD ( 20 , 21 ). In this study, the highest increase in mandibular movements was found for mouth opening, which is consistent with the research by Serrano et al ( 12 ) and Katyayana et al ( 20 ). The initial values of condyle displacement at mouth opening approach the values in asymptomatic patients from previously published studies ( 22 , 23 ) only after the occlusal splint treatment.…”

“…The condyle position in the temporomandibular joint has often been investigated, but as shown by Obrez and Gallo ( 13 ), only through the development of modern kinematic three-dimensional systems with six degrees of freedom it is possible to measure the condyle position and movement mathematically accurately. So far, the research in which such devices were used has confirmed that occlusal splint impacts the condyle position in a way that vertical displacement of the condyle between maximum intercuspation (MI) and centric relation (CR) is increased, while the horizontal and transversal condylar displacement show considerable variability ( 11 , 12 ). The objective of this pilot study was to examine the impact of the occlusal splint treatment on mandibular border movements and the condyle position in subjects with bruxism.…”

Pterygoid muscle activity in speech: A preliminary investigation

“…During speech, the mandible moves rapidly in the sagittal plane with frequent reversals in direction, and the trajectories can vary with the production of different consonants and vowels and with changes to the anterior teeth. [3][4][5] The medial pterygoid muscle (MPT), active in mandibular closing, and the lateral pterygoid muscle (LPT), active in mandibular opening, are critically important muscles in mastication, and are also likely to be two key contributors to the control of mandibular movements in speech. First, of the jaw muscles, the LPT is anatomically the best oriented to generate horizontal force vectors on the mandible in the sagittal plane, [6][7][8] and the superior, anterior, and medial orientation of each MPT 8,9 means that it can act synergistically with the LPT to provide the rapid reversals in mandibular direction in the sagittal plane during speech, and as well to help stabilise mandibular position to allow the lip and tongue muscles to operate during speech.…”

“…During speech, the mandible moves rapidly in the sagittal plane with frequent reversals in direction, and the trajectories can vary with the production of different consonants and vowels and with changes to the anterior teeth 3–5 . The medial pterygoid muscle (MPT), active in mandibular closing, and the lateral pterygoid muscle (LPT), active in mandibular opening, are critically important muscles in mastication, and are also likely to be two key contributors to the control of mandibular movements in speech.…”