Correlation between change of tongue area and skeletal stability after correction of mandibular prognathism

Evaluation of pharyngeal airway space after orthodontic extraction treatment in class II malocclusion integrating with the subjective sleep quality assessment

Orthodontic treatment with premolar extractions is typically used to relieve dental crowding and retract anterior teeth for lip profile improvement. The aim of the study is to compare the changes in regional pharyngeal airway space (PAS) after orthodontic treatment with Class II malocclusion and to identify the correlations between questionnaire results and PAS dimensions after orthodontic treatment. In this retrospective cohort study, 79 consecutive patients were divided into normodivergent nonextraction, normodivergent extraction, and hyperdivergent extraction groups. Serial lateral cephalograms were used to evaluate the patients' PASs and hyoid bone positions. The Pittsburgh Sleep Quality Index and STOP-Bang questionnaire were used for sleep quality evaluation and obstructive sleep apnea (OSA) risk assessment, respectively, after treatment. The greatest airway reduction was observed in hyperdivergent extraction group. However, the changes in PAS and hyoid positions did not differ significantly among three groups. According to questionnaire results, all three groups had high sleep quality and low risk of OSA, with no significant intergroup differences. Moreover, pretreatment-to-posttreatment changes in PAS were not correlated with sleep quality or risk of OSA. Orthodontic retraction with premolar extractions nither exhibit significant reduction in airway dimensions nor increase their risk of OSA.

Impacts of Development, Dentofacial Disharmony, and Its Surgical Correction on Speech: A Narrative Review for Dental Professionals

Speech is a communication method found only in humans that relies on precisely articulated sounds to encode and express thoughts. Anatomical differences in the maxilla, mandible, tooth position, and vocal tract affect tongue placement and broadly influence the patterns of airflow and resonance during speech production. Alterations in these structures can create perceptual distortions in speech known as speech sound disorders (SSDs). As craniofacial development occurs, the vocal tract, jaws, and teeth change in parallel with stages of speech development, from babbling to adult phonation. Alterations from a normal Class 1 dental and skeletal relationship can impact speech. Dentofacial disharmony (DFD) patients have jaw disproportions, with a high prevalence of SSDs, where the severity of malocclusion correlates with the degree of speech distortion. DFD patients often seek orthodontic and orthognathic surgical treatment, but there is limited familiarity among dental providers on the impacts of malocclusion and its correction on speech. We sought to review the interplay between craniofacial and speech development and the impacts of orthodontic and surgical treatment on speech. Shared knowledge can facilitate collaborations between dental specialists and speech pathologists for the proper diagnosis, referral, and treatment of DFD patients with speech pathologies.

Effect of Mandibular Advancement Surgery on Tongue Length and Height and Its Correlation with Upper Airway Dimensions

Introduction

The spatial position and dimensions of oral and pharyngeal soft tissues change post-mandibular advancement (MA) surgery which involves changes in position of soft palate, tongue and associated musculature. There is no study which simultaneously evaluates changes in tongue length and height post-MA surgery and correlates these changes with changes in upper airway dimensions and the amount of MA.

Materials and Methods

Treatment records of 18 patients that underwent MA with bilateral sagittal split ramus osteotomy were evaluated at T1 (01 week before surgery) and T2 (06 months post-surgery). Linear airway and tongue measurements were done on lateral cephalogram. Mean volume and mean pharyngeal area values were recorded from the acoustic pharyngometry (AP) records of patients.

Results

A statistically significant increase in tongue length (P value < 0.001) and nonsignificant change in tongue height were observed at T2 (P value > 0.05). A statistically significant increase in airway parameters recorded on both lateral cephalogram and AP was observed at T2 (P value < 0.001). Correlation analysis did not show a statistically significant correlation of change in tongue length and tongue height at T2 with the amount of MA, change in airway parameters on lateral cephalogram and AP (P value > 0.05).

Conclusions

Mandibular advancement surgery is a viable option for improvement in pharyngeal airway in skeletal Class II patients with retrognathic mandible. Changes in tongue length observed in our study may correspond to the stretch of protruders of tongue, especially genioglossus, and may point toward possible relapse on a long-term follow-up.

3D evaluation of the morphological and volumetric changes of the tongue and oral cavity before and after orthognathic surgery for mandibular prognathism: a preliminary study

BACKGROUND

The volumetric ratio of the tongue to the oral cavity has been recognized to be one of the important factors for the maintenance of stable occlusion. Oral cavity capacity is changed after orthognathic surgery in patients with mandibular prognathism; however, the volumetric changes of the oral cavity including the tongue before and after surgery have not been analyzed. The purpose of this study was to evaluate the morphological and volumetric changes of the tongue and oral cavity following orthognathic surgery using a newly developed vinyl polysiloxane impression method.

MATERIALS AND METHODS

The study was performed in fifteen subjects who underwent surgical orthognathic treatment. Impressions of the tongue together with the oral cavity were obtained before orthognathic surgery and 1, 3, and 6 months after orthognathic surgery. These impression patterns were scanned using cone-beam computed tomography (CT), and three-dimensional (3D) images of the oral cavity including the tongue, and the upper and lower dental arches were reconstructed. The morphological and volumetric changes in the oral cavity capacity and the tongue volume were examined.

RESULTS

The volume of the tongue with the volume of the oral cavity decreased after orthognathic surgery. There was a correlation between the decrease in the oral cavity capacity and tongue volume. The volumetric ratio of the tongue to the oral cavity seems to be maintained before and after orthognathic surgery.

CONCLUSION

VPS method, free from radiation exposure, may be useful for investigating the morphological and volumetric changes of the tongue and oral cavity, which may possibly influence the stability of the dental arch and occlusion during surgical orthodontic treatment.

Extension and validation of the protocol of orofacial myofunctional assessment for individuals with cleft lip and palate

PURPOSE

To perform the expansion, validation of the content, criterion and construct of an orofacial myofunctional assessment protocol for individuals with cleft lip and palate; and to define evaluation parameters for the instrument use.

METHODS

The expansion of the instrument was performed based on the MBGR protocol; the items, sub items and possibilities of answers of the amplified instrument were analyzed for their clarity by seven examiners for the content validation.. Assessment parameters were developed for the use of the instrument in order to minimize the subjectivity. Four examiners compared the aspects of the protocol to those of another instrument for the criterion validation, and the construct validation was performed comparing the results of pre and post orthognathic surgery treatment. The Content Validation Index and the Kappa, Spearman and Wilcoxon Correlation tests were applied for the validations.

RESULTS

The mobility, tonicity and sensitivity aspects of the evaluation were added to the protocol and at content validation, 72% of the items were classified as very clear and 28% as clear. A manual with assessment parameters for all items and sub items of the protocol was constructed. The inter-examiner agreement was moderate. In the comparison of the protocols, for the validation of the criterion, a good relation among them was observed. For the validation of the construct the protocol was able to identify outcome after the treatment.

CONCLUSION

The protocol was expanded and considered validated in its entirety: content, criterion and construct, and evaluation parameters for its use were established.