Smith-Magenis Syndrome—A Developmental Disorder with Circadian Dysfunction
Merlin G. Butler, F. John Meaney in Genetics of Developmental Disabilities, 2019
Craniofacial features in SMS are distinct across all ages (Fig. 2), but often subtle during infancy. The head is brachycephalic with a square-shaped face and prominent forehead. The eyes are close and deep set with upslanting palpebral fissures. Although the marked midface hypoplasia persists across all ages, it may not be fully appreciated in early infancy. In the infant/toddler stage, children with SMS have a smiling, almost angelic (cherubic) appearance, due to their rosy and pudgy cheeks, marked midface hypoplasia, and upslanting palpebral fissures. Their facial features have been described as reminiscent of the Hummel porcelain angel figurines. Eyebrows are usually heavy and dark with mild to complete synophrys that becomes more apparent with age. The nose is short (reduced nasal height) and broad with anteverted nares. The face may appear expressionless with an open mouth posture. The mouth is very distinct and characteristic of the syndrome, especially at younger ages. The upper lip is down-turned with a cupid’s bow or “tented” appearance. Micrognathia changing to relative prognathism occurs with age. In a few instances, the micrognathia may lead to a clinical diagnosis of Pierre Robin sequence with/ without associated cleft palate (2,26). The facial appearance is most distinctive by mid-childhood (school age) and appears to coarsen with age (Fig. 2). The midface hypoplasia persists into adulthood, and the lower jaw grows, becomes more angulated and exhibits relative prognathia (56).
Neuroendocrine disease
Philip E. Harris, Pierre-Marc G. Bouloux in Endocrinology in Clinical Practice, 2014
Clinical features may relate primarily to the somatic overgrowth engendered by elevated GH and IGF-I levels, to the size of the tumor itself, and/or due to symptoms of associated hypopituitarism. Key features of the condition relate to the somatic overgrowth that results in the characteristic symptoms (Table 1.12) and signs (Table 1.13) of acromegaly. Frequently, the features can best be appreciated by retrospective comparison of the patient’s photographs (Figure 1.22). Thickening of the skin is a cardinal physical sign. This thickening can be objectively demonstrated by the measurement of heel pad thickness on x-ray. As a result, venipuncture is often difficult. Skin cuts tend to heal quickly. Patients frequently describe excessive sweating and greasy skin. Skin tags are a common feature, particularly in the axilla and around the nape of the neck. Glossomegaly is also a cardinal sign. The glossomegaly can interfere with mastication that is exacerbated by prognathism and dental malocclusion.
The Basal Cell Nevus Syndrome
Roger M. Browne in Investigative Pathology of the Odontogenic Cysts, 2019
The characteristic facies of BCNS are well known and occur in 70 to 80% of patients3,4 (Figure 1). Increased size of the skull, due to bossing of the frontal and parietal bones, and overdevelopment of the supraorbital ridges are particularly common and noticeable, while hypertelorism and a broad nasal root are less constant and more variable in degree.5 Mandibular prognathism occurs in some patients, but it is not established if this is due to an absolute increase in mandibular dimensions or relative to maxillary underdevelopment. Clefting of the lip and/or palate occurs in about 5% of cases.
The Biomechanical Effects of Sagittal Split Ramus Osteotomy on Temporomandibular Joint
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2018
Zhan Liu, Jingheng Shu, Yuanli Zhang, Yubo Fan
The mandible of a patient with mandibular prognathism anteriorly overgrew, and contributed to the abnormal masticatory functions. O’Ryan and Epker’s study showed that the shape and function of the TMJ were significantly different in populations with different occlusal morphologies (O'Ryan and Epker 1984). Under the central occlusion, the contact area of the disc and condylar cartilage was greater than that of the disc and temporal cartilage, in agreement with related studie (Beek et al. 2000, 2001). The maximum and minimum contact stresses of the disc were located at the posterior band and the anterior band, respectively. However, at the contact pair of the disc and temporal cartilage, the contact stress distribution of the disc showed an opposite trend. The smaller contact stress between the disc and temporal cartilage would lead to the less stresses of the disc, located at its posterior band, consistent with the results in previous research (Beek et al. 2001; Chen et al. 1998).
Comparison of stress distribution of TMJ with different mandibular deformities under incisal clenching
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Annan Li, Bingmei Shao, Zhan Liu
A total of 34 individuals over 18 years old from the Affiliated Hospital of Stomatology of Chongqing Medical University were involved in this study, including 10 asymptomatic subjects (four females and six males, 26.7 ± 4.8 years old) as the control group, 10 patients with mandibular prognathism (seven females and three males, 23.6 ± 3.2 years), five patients with mandibular retrusion (five females and zero male, 29.2 ± 11.6 years) and nine patients with mandibular deviation (four females and five males, 22.4 ± 4.1 years). All the subjects were from the clinical cases without artificial selections. Each participant signed an informed consent agreement. The lower incisors of the subjects with mandibular prognathism were in front of the upper incisors. As for the subjects with mandibular retrusion, the lower incisor tips were behind the root of the upper incisors. If the mandibular midline deviation from facial midline is more than 3 mm, the patient is considered as having mandibular deviation. According to the previous studies (Ueki et al. 2000), for the patients with mandibular deviation to one side, this side was considered as the non-deviated side while the other side was considered as the deviated side.
Effect of sagittal split ramus osteotomy on stress distribution of temporomandibular joints in patients with mandibular prognathism under symmetric occlusions
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Hedi Ma, Jingheng Shu, Quanyi Wang, Haidong Teng, Zhan Liu
Mandibular prognathism affects the facial appearance and quality of daily life negatively. It was reported that mandibular prognathism alone accounted for 43% of all mandibular deformities (Tsang et al. 1998). Sagittal split ramus osteotomy (SSRO) is the representative orthognathic surgery for patients with mandibular prognathism (Fang et al. 2007). However, postoperative complications, such as skeletal relapse, condylar absorption, and temporomandibular joint disorder (TMD), are found to occur (Martis et al. 1984; Mitsukawa et al. 2013). Inappropriate condylar positioning can lead to postoperative complications (Rebellato et al. 1999). Biomechanical studies have demonstrated that postoperative complications are related to changes in stresses in the postoperative osteotomy area and the temporomandibular joint (TMJ) (Ueki et al. 2006). Condylar positioning is related to joint spaces. The reduction in joint spaces can lead to the squeezing of the articular disc, leading to an increase in the stress levels in the TMJ and osteoarthritis (Zhang et al. 2018). This in turn may cause pain in the joint and other symptoms of TMD. Thus, it is essential to understand the biomechanical environment of TMJ to analyse the effects of SSRO on mandibular prognathism patients.
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