The use of clear aligners is becoming more common for aesthetic orthodontic treatment, but there are still concerns about how they affect mastication biomechanics in the short and long term. The clear aligners treatment (CAT) mechanism changes the position of the mandible and maxilla, especially impacting the masseter muscle. Surface electromyography (sEMG) proves to be a useful method to evaluate masticatory muscle activity (MMA). To analyze the effect of clear aligners treatment on alterations in masticatory muscles (masseter, temporalis) using surface electromyography. Five databases (PubMed, Web of Science, SCOPUS, Cochrane Library, and Google Scholar) were searched up to March 2024. Studies in which MMA was evaluated after the installation of orthodontic clear aligners. Screening, data extraction, and quality assessments were performed by four investigators independently. The data, which evaluated temporalis and masseter muscle characteristics during CAT using surface electromyography, was extracted, and the quality of the studies was evaluated. The risk of bias was assessed using the Newcastle-Ottawa Scale (NOS). Six studies (two prospective cohort studies, three observational longitudinal studies, and one observational longitudinal case–control study) with low and moderate risk of bias were included in the qualitative synthesis. Six of these were also included in the meta-analysis. Our study investigated the dynamics of masseter and temporalis muscle activity during CAT. The results show that during maximal voluntary clenching, the masseter muscle demonstrated a significant initial increase (P < .05) followed by a subsequent non-significant decrease. It also showed that submaximal voluntary clenching consistently exhibited a significant reduction in muscle activity throughout the study period (P < .01). Assessment of muscle activity at the mandibular resting position revealed a variety of responses, with some participants showing a significant increase while others exhibited non-significant changes (P < .05, P > .05, respectively). However, the meta-analysis showed a non-significant difference in measuring masseter and temporalis muscles activity during CAT. Based on existing evidence, it is reasonable to conclude that CAT affected MMA. During maximal voluntary clenching, masseter muscle activity initially increased but later decreased, while temporalis muscle activity showed mixed results. Submaximal voluntary clenching revealed a consistent decrease in muscle activity over time. Mandibular resting position assessments showed both increases and no significant changes in muscle activity. However, the existing literature is insufficient to draw concrete conclusions; therefore, well-conducted further research is needed to confirm this statement. This systematic review and meta-analysis were registered in the International Prospective Register of Systematic Reviews (PROSPERO CRD42024522231).

Background and Objectives: Recent years have been marked by a search for new relationships between malocclusions and the morphological features of the cranial base and upper cervical spine. The aim of this study was to evaluate the relationship between skeletal orthodontic malocclusions and the morphological features of sella turcica bridging (STB) and ponticulus posticus (PP). Materials and Methods: The study sample consisted of 300 randomly selected pre-orthodontic treatment patients aged 7–40 years. Cephalometric analysis was performed twice by two researchers. The patients were divided into three groups according to the type of skeletal malocclusion. Statistical analysis was performed using SPSS 29.0 software. Results: The prevalence of incomplete PP was 40%, and the prevalence of complete PP was 11.33% and was significantly more common in males (56.7%). STB had a prevalence of 52.67% (15.67% complete, 37.0% partial), with a significantly higher prevalence in females (60.1%, p < 0.001). PP and STB were more common in Class II patients, followed by Class I and Class III. However, only PP showed a statistically significant difference (p = 0.042). According to logistic regression, men were twice as likely to have an open groove of PP (p = 0.015), while females had higher odds of partial and complete STB (p < 0.05). Class II malocclusion increases the odds of type 2 and type 4 PP as well as partial STB. However, it was not statistically significant (p > 0.05). Conclusions: The morphological features of sella turcica bridging and ponticulus posticus were related to sex and the orthodontic skeletal pattern. Ponticulus posticus was more prevalent in males, while sella turcica bridging was more prevalent in females; both conditions were more common in patients with a Class II skeletal pattern. Males were more likely to have an open groove of ponticulus posticus, whereas females were twice as likely to have both forms of sella turcica bridging.

The growth and development of the maxillofacial complex share a common embryological origin with the cranial base and upper cervical spine; therefore, anomalies in these regions may be linked to variations in the skeletal pattern. This study aimed to evaluate the relationships between the morphological features of the sella turcica bridging, ponticulus posticus, posterior arch deficiency of the first cervical vertebra, known as the atlas, and the cervical vertebral maturation stages and vertical malocclusions. Randomly selected 300 pre-orthodontic treatment patients (aged 7 to 40 years) were divided into groups according to cervical stage (CS1-CS6) and type of vertical malocclusion. According to the study protocol, cephalometric analysis and evaluation of the sella turcica and atlas were performed twice by two researchers under the supervision of a radiologist. Statistical analysis was performed using SPSS 29.0. Sella turcica bridging was significantly more common in postpubertal patients (58.2%; p < 0.05). Ponticulus posticus and sella turcica bridging occurred more frequently in patients with low mandibular plane angle (43.3% and 51.1%, respectively), whereas atlas posterior arch deficiency occurred more frequently in patients with high mandibular plane angle (24.2%). However, only atlas posterior arch deficiency showed significant difference (p < 0.05). According to logistic regression, patients in the CS6 stage were less likely to have type 1 ponticulus posticus and more likely to have type 2 sella turcica bridging (p < 0.05). Patients with low angle were less likely to have atlas posterior arch deficiency (p < 0.05). Sella turcica bridging and atlas posterior arch deficiency are associated with the skeletal pattern and cervical stage. Sella turcica bridging was more prevalent during the postpubertal period, whereas atlas posterior arch deficiency was more prevalent in those with a high mandibular plane angle.