Mentolabial angle and aesthetics : a quantitative investigation of idealized and normative values

BACKGROUND: This study is a quantitative evaluation of the influence of the mentolabial angle on perceived attractiveness and threshold values of desire for surgery. METHODS: The mentolabial angle of an idealized silhouette male Caucasian profile image was altered incrementally between 84° and 162°. Images were rated on a Likert scale by pretreatment orthognathic patients (n = 75), lay people (n = 75) and clinicians (n = 35). RESULTS: A mentolabial angle of approximately 107° to 118° was deemed the most attractive, with a range of up to 140° deemed acceptable. Angles above or below this range were perceived as unattractive, and anything outside the range of below 98° or above 162° was deemed very unattractive. A deep mentolabial angle (84°) or an almost flat angle (162°) was deemed the least attractive. In terms of threshold values of desire for surgery, for all groups, a threshold value of ≥162° and ≤84° indicated a preference for surgery, although clinicians were least likely to suggest surgery. The clinician group was the most consistent, and for many of the images, there was some variation in agreement between clinicians and lay people as to whether surgery is required. There was even more variability in the assessments for the patient group. CONCLUSIONS: It is recommended that in orthognathic and genioplasty planning, the range of normal variability of the mentolabial angle, in terms of observer acceptance, is taken into account as well as threshold values of desire for surgery. The importance of using patients as observers in attractiveness research is stressed

Relationship among unilateral TMJ osteoarthritis/osteoarthrosis, mandibular asymmetry and the EMG activity after performing orthognathic surgery

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Relationship between head posture and dentofacial morphology in patients with TMJ osteoarthritis/osteoarthrosis.

AIM: To test whether there is a relationship between head and cervical posture and dentofacial morphology in patients with temporomandibular joint osteoarthritis/osteoarthrosis (OA). METHODS: The subjects consisted of 34 Japanese females with TMJ OA (aged 24.7 +/- 6.1 years). Six craniocervical angular measurements were constructed for head posture. Two angular and 6 linear measurements were constructed for the skeletal relationship, while 1 angular and 6 linear measurements were constructed for the dental relationship. Pearson correlation coefficients were calculated between head posture and dentofacial variables. RESULTS: In the skeletal relationship, increased craniocervical angulations were significantly associated with a more posterior position of the maxilla, a decreased Frankfort to mandibular plane angle, decreased mandibular length, and a decreased lower facial height. In the dental relationship, increased craniocervical angulations were significantly associated with more posterior positions of the anterior teeth to the basal bone and decreased alveolar height of the anterior-posterior teeth. CONCLUSION: The hypothesis was rejected. These results suggest that an association may exist between head and cervical posture and dentofacial morphology in patients with TMJ OA.link_to_subscribed_fulltex

Relationship between the unilateral TMJ osteoarthritis/osteoarthrosis, mandibular asymmetry and the EMG activity of the masticatory muscles: A retrospective study

The purpose of this retrospective study was to investigate the relationship between the unilateral temporomandibular joint (TMJ) osteoarthritis/ osteoarthrosis (OA), mandibular asymmetry and electromyographic (EMG) activity of the masticatory muscles. Twenty-two Japanese women (aged 23·2 ± 5·4 years) and 10 Japanese men (aged 22·4 ± 2·8 years) exhibiting unilateral TMJ OA were included in this study. Two angular and seven linear measurements were obtained for the analysis of the skeletal hard tissues. The cephalometric measurement values (CV) were normalized using the CV ratio for the evaluation of the degree of mandibular asymmetry. The EMG was recorded during maximal voluntary clenching efforts for 10 s in the intercuspal position. The average values of integral EMG (iEMG) of three trials were normalized using the iEMG ratio for the evaluation of the functional balance of the masticatory muscles. The mandibular midline was shifted to the TMJ OA side with a median value of 9·85 mm. The CV ratio of the ramus height of the TMJ OA side was significantly smaller than that of the non-OA side. For the masseter muscle, the iEMG ratio of the TMJ OA side was significantly larger than that of the non-OA side (P < 0·05). These results suggest that unilateral TMJ OA is related to the dentofacial morphology, thus resulting in a mandibular midline shift to the affected side and it is associated with a masticatory muscle imbalance. © 2009 Blackwell Publishing Ltd.link_to_subscribed_fulltex

TMJ osteoarthritis/osteoarthrosis and dentofacial morphology in Japanese females

The temporomandibular joint (TMJ) is the principal adaptive center for determining the intermaxillary relationship in all three planes of space. The joint diseases, such as TMJ osteoarthritis/osteoarthrosis (OA) might associate with dentofacial morphologic changes. The purpose of this study was to investigate the relationship between TMJ OA and dentofacial morphology in Japanese females and compare findings to a normal control group. The subjects consisted of 24 Japanese females with TMJ OA (aged 22.5 ± 4.4 years) and a control group of 24 asymptomatic Japanese females (aged 23.6 ± 1.3 years). Linear and angular cephalometric measurements were noted to evaluate the skeletal, dental and soft tissue relationships of the two groups. Unpaired t-tests were used to compare the mean differences of each cephalometric measurement between the TMJ OA and the control group. The subjects with TMJ OA had a more significant posteriorly rotated mandible as well as a smaller mandible compared with the subjects in the control group. They also had more protrusive lower incisors, upper lips and lower lips. These results suggest that there might exist association between TMJ OA and dentofacial morphology in Japanese females. © 2006 Elsevier Ltd and the Japanese Orthodontic Society.link_to_subscribed_fulltex