Ability to control directional lip-closing force in skeletal class III patients.

BACKGROUND: The relationship between the maximum lip-closing force (LCF) and malocclusion has long been studied. Recently, a method to measure the ability to control directional LCF from eight directions (upper, lower, right, left and the four directions in between) during lip pursing was established. OBJECTIVE: It is considered important to evaluate the ability to control directional LCF. The aim of this study was to investigate the ability of skeletal class III patients to control directional LCF. METHODS: Fifteen skeletal class III patients (mandibular prognathism group) and 15 people with normal occlusion (normal occlusion group) were recruited. The maximum LCF and the accuracy rate (the ratio of the matched time in which the participant was able to keep the LCF in the target range over a total time of 6 s) were measured. RESULTS: The maximum LCF was not significantly different between the mandibular prognathism group and the normal occlusion group. The accuracy rate in the mandibular prognathism group was significantly lower in all six directions than that in the individual normal occlusion group. CONCLUSION: As the accuracy rate in all six directions was significantly lower in the mandibular prognathism group than that in the normal occlusion group, occlusion and craniofacial morphology might influence lip function.

Morphological changes in the temporomandibular joint before and after sagittal splitting ramus osteotomy of the mandible for skeletal mandibular protrusion.

Changes of temporomandibular joint (TMJ) morphology were analyzed in 21 patients with mandibular protrusion corrected using bilateral sagittal split ramus osteotomy (SSRO) and mini-plate fixation with TMJ cephalometric laminographs. The condylar pass angle, eminence to the FH plane angle, and total height of fossa and lower height of fossa in both left and right sides, significantly decreased after surgery. The width of the condyle, in both left and right sides, significantly increased after treatment. However, in the joint spaces, there were no significant differences before and after treatment. The amount of change in the eminence to the FH plane angle, total height of fossa and lower height of fossa, before and after surgery, showed significant positive correlations with that of SNB, before and after surgery. These results suggest that adaptive bone remodeling of the TMJ might occur due to the correction of occlusion and craniofacial morphology by SSRO in patients with mandibular protrusion.

A cross-sectional study on the relationship between craniofacial morphology and the coronoid process.

Although there have been some reports on the relationship between craniofacial morphology and the activity of the temporal muscle attached to the coronoid process, such relationship is still unclear. The aim of the present study was therefore to investigate the relationship between the coronoid process and overall craniofacial morphology using lateral cephalograms of 60 female subjects (mean age 9.6 years) without mandibular deviation. Statistical testing was undertaken using stepwise regression analysis. Anterior coronoid marginal depth correlated negatively (r = 0.71) with gonial angle, SNA, and overjet. The coronoid angle also correlated negatively (r = 0.86) with both the vertical and horizontal lengths from sella to the coronoid tip as well as with the horizontal length from sella to the posterior ramus margin. Furthermore, the coronoid length correlated positively (r = 0.61) with the coronoid angle and the anterior coronoid marginal depth. The coronoid width was also positively (r = 0.69) correlated with overbite. Coronoid process morphology is related not only to mandibular morphology and position but also to maxillary position and the dental relationship in the anterior region. It therefore seems clear that coronoid process morphology might be related to temporal muscle functioning and its associated craniofacial morphological measurements.

Unilateral condylar bone deformity and slope of articular eminence related to mandibular asymmetry.

The present study was undertaken to investigate the correlation between condylar position, articular eminence morphology, and mandibular deviation using helical CT in a group of 22 female subjects (mean age 19.2+/-5.3 years) with mandibular deviation. There was a significant difference in the angles of the posterior-slope of the articular eminence (PSA) between the deviated (44.27+/-10.29 degrees) and non-deviated (42.50+/-9.90 degrees) sides. Mandibular deviation also correlated significantly with both medial joint space (r=0.581) and the PSA (r=0.653). A significant negative correlation was also found between mandibular deviation and the anterior/posterior joint space ratio (r=-0.450). These results demonstrated that patients with mandibular deviation possibly show asymmetries not only in their glenoid fossa morphology but also in their condylar position.

Postoperative stability of bimaxillary surgery in Class III patients with mandibular protrusion and mandibular deviation: a frontal cephalometric study.

The aims of this study into bimaxillary surgery were to investigate and compare the postoperative stability of deviated side (lengthened side) and non-deviated side (shortened side), the effect of the type of surgery performed in the mandible, and the changes in signs and symptoms of temporomandibular joint (TMJ) disorders before and after surgery. The sample consisted of 31 Class III patients in whom imbalance between the maxilla and the mandible were corrected by Le Fort I osteotomy combined with bilateral intraoral vertical ramus osteotomy (BIVRO group, n=9), bilateral sagittal split ramus osteotomy (BSSRO group, n=10), or IVRO and SSRO (IVRO+SSRO group, n=12). IVRO+SSRO and BIVRO are more effective in improving TMJ signs and symptoms. There was no significant post-surgical difference between deviated and non-deviated sides in any group. BIVRO and BSSRO showed excellent post-surgical stability on both sides; less was found in the IVRO+SSRO group. The IVRO+SSRO group showed greater transverse displacement in menton point than the BIVRO group. In conclusion, after bimaxillary surgery and in asymmetric patients there were no differences between deviated and non-deviated sides, BIVRO and BSSRO appear to be more stable than IVRO+SSRO.

A precise and useful method for coordinating computed tomography and jaw movement frames of reference.

PURPOSE: The aim of this study was to develop a means of coordinating helical computed tomography (CT)- based morphological data in 3 dimensions (3-D) with that pertaining to jaw movement as recorded by a device that measures jaw movement in six-degrees-of-freedom (6-DOF), thus producing multi-point movement analysis of the condyle. METHODS: The study sample was two volunteers. One of the subjects had erosive bony changes in both condyles, while the other had healthy condyles. We employed a customized facebow, which enabled us to coordinate jaw movement data and morphological volume data from CT. Total uncertainty of the coordination was computed, according to International Organization for Standardization (ISO). In order to demonstrate the effects of multi-point analysis for complex condylar movement, we tried to visualize the trajectory of the working condyle in lateral excursion. RESULTS: The overall uncertainty at a condylar center chosen as an example to illustrate the method was 0.38 mm, 0.19 mm, and 0.50 mm in antero-posterior, lateromedial, and supero-inferior directions, respectively, in terms of 95% coverage as defined by the ISO. CONCLUSION: We developed facebow-based X-ray markers with high clinical operability, which could correlate the helical CT's coordinate system with our 6-DOF jaw movement measuring system for precise analysis of 3-D condylar movements. In motion analysis of rotational condyle, even a small amount of measurement error cannot necessarily be neglected. Then, a multi-point approach such as that realized by our system presents the best option.

Morphological changes in the temporomandibular joint after orthodontic treatment for Angle Class II malocclusion.

OBJECTIVE: The aim of this study was to examine the morphological temporomandibular joint (TMJ) changes that occur after orthodontic treatment in patients with Angle Class II malocclusion. METHODS: The post-treatment changes in TMJ morphology were analyzed, based on TMJ cephalometric laminographs in 19 patients with Angle Class II malocclusion and labial inclination of the upper incisors after premolar extraction. RESULTS: The condylar pass angle, articular eminence to the Frankfort horizontal plane angle, and total, upper, and lower heights of the articular fossa increased significantly on both sides after treatment and retention. The anteroposterior width of the articular fossa decreased significantly on both sides after treatment and retention. DISCUSSION: These results suggest that adaptive bone remodeling of the TMJ occurs during the correction of occlusion with labial inclination of the upper incisors by orthodontic treatment after premolar extraction in patients with Angle Class II malocclusion.

Temporal change in the occlusal vertical dimension and its involvement in modulation of jaw movement in bite-reduced animals.

The occlusal vertical dimension (OVD) in guinea pigs is maintained by tooth eruption and grinding. It has been reported that the experimentally raised OVD recovers to the innate OVD within a few days in guinea pigs. However, the mechanisms underlying OVD adjustment are not entirely understood. This study thus aimed to clarify whether the experimentally reduced OVD would recover. Bite-reduced guinea pigs were created by applying bilateral intermaxillary elastics for 10 days. Guinea pigs without elastics were used as a control. The OVD after removal of the elastics in the experimental group was compared with that of the control group. Jaw movement during chewing was also compared between the experimental and control groups. After removal of the elastics, the experimentally reduced OVD did not recover fully and a significant difference was observed between the experimental and control groups for up to 25 days during the recording period. The minimum closed position during chewing was significantly higher in the experimental group than in the control group, whereas the maximum open position was no different between the groups. The present findings indicated that the experimentally reduced OVD could not be fully recovered, suggesting that reduction of the OVD may have limited influence on jaw movement.

Soft-tissue cephalometric norms in Yemeni men.

INTRODUCTION: The main purpose of this study was to develop soft-tissue cephalometric standards for Yemeni men and compare them with the cephalometric standards of normal North American white people. METHODS: Fifty Yemeni men (ages, 20-27 years; mean, 23.1 years) with normal occlusion were selected. With double selection by orthodontists and laypersons, a subsample of esthetically pleasing subjects was selected. Lateral cephalometric radiographs of all subjects were analyzed according to the Legan-Burstone and the Holdaway analyses. RESULTS: The Yemeni esthetically pleasing subjects (YPG) and the remaining subjects (YNG) showed significant differences with respect to mandibular prognathism, lower face-throat angle, nasolabial angle, mentolabial sulcus depth, and interlabial gap, when compared with the Legan-Burstone norms for white Americans; the YPG also had significantly less obtuse facial convexity angle than the YNG. Most values of both Yemeni groups were generally within the range of the values reported by Holdaway, except for 3 variables: skeletal profile convexity, basic upper-lip thickness, and H-angle, which were all significantly larger than those of Holdaway; the YPG showed less skeletal profile convexity than the YNG. CONCLUSIONS: These results show that the soft-tissue facial profiles of white Yemenis and Americans are different in certain respects; these racial differences must be considered during diagnosis and treatment planning. These results should serve as a useful reference for orthodontists and maxillofacial surgeons who treat Yemeni patients and also contribute to more satisfactory diagnosis and treatment planning for them.

Analysis of head and mandibular tapping movements in patients with mandibular protrusion.

The present study was conducted to investigate whether there was a functional coupling between the head and mandibular movements in ten patients with mandibular protrusion (MP) and ten control subjects with normal occlusion (Normal), using a six degrees-of-freedom measuring device. Single-peak waveforms were predominantly seen in both MP (98.2%) and Normal (99.3%). However, vertical displacements of the upper and lower incisor points (VD(UIP) and VD(LIP)) were all significantly larger in MP than those in Normal. The ratio VD(UIP)/VD(LIP) also increased more sharply with an increase in VD(LIP) in MP, compared to that in Normal. Mandibular rotation in MP was also significantly larger than that in Normal. The results showed that, in MP, the head moves more vertically in rhythmical coordination with mandibular movement during tapping. Finally, it may be that this larger vertical head movement is related to the greater condylar rotation in MP subjects.

Association between number of teeth present and mandibular cortical erosion in Japanese men and women aged 40 years and older: A cross-sectional study.

Mandibular cortical erosion detected on dental panoramic radiographs is associated with increased risk of osteoporosis in older adults. Additionally, many reports have demonstrated an association between decreased number of teeth present and osteoporosis. However, whether mandibular cortical erosion is associated with a decreased number of teeth remains unclear. The purpose of this study, therefore, was to clarify the association between mandibular cortical erosion and number of teeth present in Japanese men and women aged 40 years and older. Among patients who visited our university hospital and underwent dental panoramic radiography for the diagnosis of dental diseases, 839 patients (293 men and 546 women) aged 40-89 years (mean [SD], 63.7 [10.6] years) participated in this study. Multiple regression analysis revealed that mildly to moderately eroded cortex (p = 0.007) and severe eroded cortex (p < 0.001) were significantly associated with a decreased number of teeth present. Analysis of covariance adjusted for covariates revealed a significant association between mandibular cortical erosion category and number of teeth present (p < 0.001). Subjects with a severely eroded cortex had significantly fewer teeth present than those with a normal cortex (mean [SE], 20.7 [0.5] vs. 23.4 [0.3], p < 0.001) or mildly to moderately eroded cortex (22.2 [0.4], p = 0.04). Subjects with a mildly to moderately eroded cortex had significantly fewer teeth present than those with a normal cortex (p = 0.033). Our results suggest the significant association between mandibular cortical erosion and number of teeth present in Japanese men and women aged 40 years and older.

Double contours and craniofacial morphology.

This study was done to try to clarify the relationship between double contours and craniofacial morphology. The study sample included 56 pre-orthodontic patients with signs and symptoms of temporomandibular joint (TMJ) disorders. A comparison of craniofacial structures was done on 32 subjects with bilateral condylar bone change (BBC group: 28 female and 4 male) and 24 subjects with no condylar bone change (NBC group: 21 female and 3 male). The BBC showed significantly greater antegonial and ramus notch depths, as well as significantly more retruded mandibles, shorter ramus heights, and larger mandibular plane angles than the NBC. BBC subjects with bilateral double contours showed significantly more retruded mandibles, larger antegonial notch depth, and shorter lengths from the Sella to the Articulare than BBC subjects with no double contours. The study showed that important relationships exist between the presence of double contours and mandibular morphology and TMJ position.

Craniofacial morphology and inclination of the posterior slope of the articular eminence in female patients with and without condylar bone change.

This study investigated the association of craniofacial and glenoid fossa shapes and temporomandibular joint (TMJ) pathology in 39 orthodontic patients with signs and symptoms of TMJ disorders, using helical CT scans. Cephalometric measurements showed that 21 subjects with bilateral condylar bone change (BBC) had significantly smaller SNB angles, ramus heights and S-Ar/N-Ba ratios, as well as larger mandibular plane angles and lower anterior facial height than the 18 subjects with no condylar bone change (NBC). The average posterior slope of the left and right articular eminence in their central and lateral sections was significantly steeper in NBC than in BBC. Condylar bone change might, therefore, not only be related to the morphology of the mandible, but also of the glenoid fossa and cranial base. This appears to reflect adaptive changes in the condyle, articular eminence and cranial base in response to changes in loading.

Condylar bone change and sagittal incisal and condylar paths during mandibular protrusive excursion.

This study showed significant differences in sagittal condylar and incisal path angles during mandibular protrusive excursion, as well as flattening of the condylar path related to the existence and type of condylar bone change. Twenty-eight (28) patients with signs and symptoms of TMJ disorders were studied, using a six-degrees-of-freedom measuring device and helical CT. Sagittal incisal and condylar path angles at two mm and three mm condylar path lengths (CPL) were significantly shorter in the bilateral condylar bone change (BBC), compared to the no bone change (NBC) group. Also, NBC incremental sagittal condylar path angles from three to five mm CPL and NBC condylar path curvature at five mm CPL were both significantly larger than in BBC. Comparing types of bone change, incremental sagittal condylar path angles from three to five mm CPL was significantly less in osteophyte than in NBC or erosion groups. Condylar path curvature at five mm CPL was also significantly less in osteophyte than in NBC.

Single-action implantation of a 3-piece acrylic intraocular lens with an injector.

We report a method to insert a 3-piece AcrySof MA30BA acrylic foldable intraocular lens (IOL) (Alcon) in a single action using a Monarch II (Alcon) injector. The technique was used in 134 eyes. The incision widths ranged from 3.00 to 3.75 mm. The IOLs were successfully inserted in the capsular bag. Complications included cracks in the IOL optic in 3 eyes (3%), haptic damage in 3 eyes (3%), and inadequate self-sealing of the incision in 18 eyes (13%).

The relationship between morphological changes of the condyle and condylar position in the glenoid fossa.

AIMS: To investigate whether condylar morphological changes influence the condyle position in the glenoid fossa as well as the amount of condylar movement from the intercuspal position (IP) to the reference position (RP). METHODS: Helical computed tomography was used for precise measurement of the joint spaces at IP and RP in 22 subjects (mean age 22.7 years). Subjects were divided into 2 groups, those without condylar bone changes (n = 11) and those with condylar bone changes (n = 11). The latter group was further subdivided into a flattening subgroup and an osteophyte subgroup, according to the type of condylar bone change. RESULTS: There were no significant differences in the width of the anterosuperior or posterosuperior joint spaces at IP between either the 2 groups or the 2 subgroups. On the other hand, during condylar movement from IP to RP, the condyles moved significantly more superiorly and posterosuperiorly in the bone-change group than in the no-bone-change group. There was also greater absolute horizontal condylar movement between IP and RP in the bone-change group. In addition, within the bone-change group, the type of condylar bone change influenced the amount of condylar movement. Joints with osteophyte formation showed the most superior, posterosuperior, and absolute horizontal movement from IP to RP. CONCLUSION: The findings that condyles of the bone-change group, especially those with osteophyte formation, were located significantly more anteroinferiorly in the glenoid fossa at IP than RP than the condyles of the no-bone-change group suggest that condylar IP-RP positional changes might be related to condylar shape alteration.

The relationship between retruded contact position and intercuspal position in patients with TMJ osteoarthritis.

This study was conducted to investigate the relationship between posterior mandibular excursion movement and temporomandibular joint osteoarthntis (TMJ OA) in 25 orthodontic patients with Angle Class I and Class II, using a six degrees-of-freedom measuring device and helical computed tomography. There were significant differences found in three-dimensional length, antero-posterior, absolute latero-medial and supero-inferior incisal, and condylar intercuspal position (IP)-retruded contact position (RCP) slides between bilateral, unilateral, and no condylar bone change groups. With respect to the types of condylar bone change, there were significant differences found in three-dimensional length, antero-postenor, and absolute latero-medial condylar IP-RCP slides between flattening, erosion and osteophyte groups. These results suggest that large three-dimensional, not only incisal but also condylar, IP-RCP slides might be related to the uni-/bilaterality and kind of TMJ pathosis, which might make such slides useful as clinical indices of TMJ OA.

Can the presence of carotid artery calcification on panoramic radiographs predict the risk of vascular diseases among 80-year-olds?

OBJECTIVE: The purpose of this study was to evaluate whether subsequent vascular diseases and related death could be predicted by the presence of carotid artery calcification detected on panoramic radiographs among elderly persons. STUDY DESIGN: We evaluated 659 panoramic radiographs from 262 male and 397 female 80-year-old subjects and their general medical examination data to assess the relationship between the presence of carotid artery calcification and vascular disease risk at baseline examination. Of these subjects, the occurrence of vascular diseases within 5 years after baseline examination was examined in 191 subjects. Further, the causes of death were examined in 108 subjects who died within 5 years after baseline examination. RESULTS: There was a significant difference in the history of past vascular diseases among subjects with and without carotid artery calcifications; however, no significant difference in the occurrence of subsequent vascular diseases was found among them. Further, there was no significant difference in the occurrence of vascular disease-related death within 5 years after baseline examination among subjects with and without carotid artery calcifications (P = 0.719). CONCLUSION: Our results suggest that the presence of carotid artery calcifications on panoramic radiographs may be related to the history of past vascular diseases; however, this is not a useful marker for subsequent vascular diseases and related death among 80-year-olds.

Effect of sevelamer on dyslipidemia and chronic inflammation in maintenance hemodialysis patients.

BACKGROUND: Hemodialysis (HD) patients often experience cardiovascular events, that might be related to altered calcium-phosphate metabolism, dyslipidemia, and chronic inflammation in addition to hypertension. Sevelamer, a non-calcium-containing phosphate binder, may improve the lipid profile of HD patients. However, the influence of sevelamer on chronic inflammation has not been clarified. METHODS: We enrolled 36 maintenance HD patients with a serum calcium (Ca) or phosphate (P) level constantly greater than 9.5 mg/dL and 5.5 mg/dL, respectively. The dose of sevelamer was titrated to achieve a serum Ca and P in the target ranges. The study period was 24 weeks. Patients underwent the following measurements: bone mineral markers, lipids, and a high-sensitivity C-reactive protein (hs-CRP). RESULTS: In the 28 patients who completed the study, sevelamer significantly reduced the mean non-high-density lipoprotein cholesterol (non-HDL-C) level by 15% and 20% (p < 0.0001) after 12 and 24 weeks, respectively, in addition to reducing the serum P level and Ca x P product. Similarly, there was a significant reduction of the serum hs-CRP level after 12 and 24 weeks [median at baseline: 1.03 mg/dL (interquartile range 0.26-3.98 mg/dL) versus 0.57 (0.17-1.47) and 0.38 (0.16-1.03), respectively, p = 0.0259]. The reduction rate of hs-CRP was significantly correlated with those of non-HDL-C (r = 0.451, p < 0.0401) and P (r = 0.453, p < 0.0008) CONCLUSION: Hs-CRP levels were reduced by sevelamer administration, as well as non-HDL-C, P, and the Ca x P product. Sevelamer may have an anti-inflammatory effect, in addition to lowering phosphate and lipid levels in HD patients.

Relationship between facial asymmetry and masseter reflex activity.

PURPOSE: In this study, we evaluated the tonic vibration reflex (TVR) of the masseter muscles in patients with facial asymmetry. SUBJECTS AND METHODS: The study was conducted with 10 volunteers without facial asymmetry and 12 orthognathic patients with facial asymmetry. Subjects were seated in a chair and held a stimulator composed of an electric motor and an acrylic bite block between the upper and lower dentitions at facial midline, to elicit TVR. Electromyographic activity was recorded using a pair of silver electrodes affixed bilaterally with adhesive tape to the skin over the superficial masseter. The amount of mandibular deviation was measured on the frontal cephalogram. The reflex response was evaluated with the following: TVR index (%) = integral TVR x 100/ integral maximum voluntary contraction (MVC), and with the TVR ratio: integral TVR on the high MVC side/ integral TVR on the low MVC side. RESULTS: In the patient group, the average TVR index on the deviated side was significantly higher than that on the nondeviated side. In all subjects, including the control and patient groups, a negative correlation between the amount of mandibular deviation and the side-to-side difference in TVR index was seen (r = -0.536, P <.05, n = 22). In addition, patients with a lower MVC on the deviated side than on the nondeviated side showed a significantly higher TVR ratio than did the control group. CONCLUSIONS: These results suggest that the difference between the right and left reflex responses elicited by TVR might be related to frontal craniofacial morphology.