Longitudinal Quantitation of Tooth Displacement in Chinese Adolescents with Normal Occlusion

This longitudinal study aims to analyze the different modes of the maxillary and mandibular tooth displacement in subjects,who were aged 12.5-17.5 years(150-210 months),with untreated normal(Class I)occlusion.Longitudinal lateral cephalograms for a set of 10 subjects(7 females and 3 males)at consecutive annual time points were selected and monitored.Data were analyzed on the basis of the superimpositions of serial tracings of lateral cephalograms on stable anterior cranial base,the anatomies of the maxillary and mandibular structures.The horizontal and vertical displacements of the first molar and incisor were assessed by r-test.The local and the secondary tooth displacements with growth contributed to the total horizontal and vertical displacements of the molars and incisors of the subjects.In the total tooth displacement,the horizontal growth of maxilla and mandible had the same contribution as the local tooth displacements.The vertical maxillary growth played a smaller role than the local drift,and mandibular remodeling went in a reverse direction with the local tooth drift.The first molars moved more forward than the incisors in the upper and lower arches.Both the upper and lower first molars showed forward tipping.The analysis of tooth displacement may be utilized in making orthodontic treatment plan,including anchorage or torque control.

The Craniofacial Morphology in Adult Patients with Unoperated Isolated Cleft Palate

Objective： To address the effect of intrinsic factors on craniofacial growth by analyzing the craniofacial morphology of unoperated isolated cleft palate in Chinese adult. Materials and Methods： This study included 37 nonsyndromic isolated cleft palate and 39 age and gender matched non-clefts. Twenty-six cephalometric measurements were employed to evaluate the facial morphology. Independent samples T test and Mann- Whitney U were used for comparison. Significant difference was defined at 95% level. Results： Data from this study showed patients with unoperated isolated cleft palate have a reduced maxillary sagittal length （ANS-PMP, A-PMP, P〈0.05）, a smaller ANB angle （ANB, P〈0.05） and a retrusive ANS point （S-N-ANS, P〈0.05; Ba-N-ANS, P〈0.05）. Measurements descripted position of maxilla （S-Ptm, P〉0.05）, depth of bony pharynx （Ba-PMP, P〉0.05）, anterior and posterior maxillary height （N-ANS, P〉0.05; R-PMP, P〉0.05） and mandible morphology （including linear measurements and angle measurements） did not show any significant difference between case and control groups. Conclusions： Patients with isolated cleft palate were characterized by maxillary retrusion. Mandible morphology and cranial basal morphology in isolated cleft palate showed no significant difference with nonclefts. Patients with isolated cleft palate are more vulnerable to cross bite than nonclefts. Intrinsic deficiencies did detrimental effect on maxilla sagittal length, but did no detrimental effect on maxilla position, mandible size and position.

Successful Treatment of Postpeak Stage Patients with ClassⅡ Division 1 Malocclusion Using Non-extraction and Multiloop Edgewise Archwire Therapy: A Report on 16 Cases

Aim To determine cephalometrically the mechanism of the treatment effects of non-extraction and multiloop edgewise archwire （MEAW） technique on postpeak Class Ⅱ Division 1 patients. Methodology In this retrospective study, 16 postpeak Class Ⅱ Division 1 patients successfully corrected using a non-extraction and MEAW technique were cephalometrically evaluated and compared with 16 matched control subjects treated using an extraction technique. Using CorelDRAW software, standardized digital cephalograms preand post-active treatments were traced and a reference grid was set up. The superimpositions were based on the cranial base, the mandibular and the maxilla regions,and skeletal and dental changes were measured. Changes following treatment were evaluated using the paired-sample t-test. Student＇s t-test for unpaired samples was used to assess the differences in changes between the MEAW and the extraction control groups. Results The correction of the molar relationships comprised 54% skeletal change （mainly the advancement of the mandible） and 46% dental change. Correction of the anterior teeth relationships comprised 30% skeletal change and 70% dental change. Conclusion The MEAW technique can produce the desired vertical and sagittal movement of the tooth segment and then effectively stimulate mandibular advancement by utilizing the residual growth potential of the condyle.

Compensatory Head Posture Changes in Patients with Obstructive Sleep Apnea

Summary: The upper airway narrowing and changes in head posture and their relationship with apnea seventy in patients with obstructive sleep apnea (OSA) were investigated. In 86 male OSA patients and 37 healthy men, one-night polysomnographic examination was performed and a lateral cephalogram by digital image processing system was taken in each subject. Fifteen variables concerning the upper airway dimensions, area and head postures were measured by using a computer software (NIH Image). The results showed that upper airway dimensions in the OSA group at all levels were significantly smaller than those in the control group and the results hold true when the age and body mass index were well controlled in these two groups. Significant forward inclination of the cervical column was found in the patients with an apnea index (AI) greater than 35 episodes/h. And changes in the head posture variables in the whole study group were significantly correlated with AI and airway dimensions at various levels. It was suggested that there exist significant and extensive upper airway narrowing in OSA patients even in upright position and awake state; And as the apnea seventy progresses, patients may assume certain compensatory head postures in an attempt to maintain an adequate airway patency.

Sex Predictive Value of Frontal Sinus Index Compared to Maxillary Sinus Index:Lateral Cephalometric Study

Sex estimation is a crucial step to outline the biological profile of unknown human remains.The frontal and maxillary sinuses have unique anatomical features and can be utilized efficiently in individual identification.Previous studies investigated the frontal and maxillary sinus indexes separately for sex prediction.However,comparing the predictive value of the frontal sinus index(FSI)to the maxillary sinus index(MSI)has not been investigated yet.This study aimed to evaluate the sex predicting value of FSI compared to MSI assessed on digital lateral cephalometry.This retrospective cross-sectional study included 88 digital lateral cephalometric images of known sex(44 males and 44 females)and age(20-50 years).Two radiologists measured the maximum anteroposterior sinus width and height of the frontal sinus and maxillary sinus.Then,the sinus index was calculated for each radiograph.The obtained frontal and maxillary sinuses parameters were tabulated,along with the patient’s sex and age,and subjected to statistical analysis.Our results revealed significant differences between males and females regarding frontal sinus width,FSI,and MSI.The discriminant function analysis obtained in this study accurately predicted sex with an overall accuracy of 71.6%(81.8%of males and 61.4%of females)using FSI,and 60.2%(63.6%in females and 56.8%in males)using MSI.Frontal and maxillary sinus indexes can be useful tools for sex prediction.Discriminant function equations were developed for both the frontal and maxillary sinus indexes with higher accuracy rates for FSI compared to MSI.

X线头影测量与阻塞性睡眠呼吸暂停低通气综合征

X线头影测量能较好的显示上气道软组织和硬性解剖结构的关系,为阻塞性睡眠呼吸暂停低通气综合征(obstructive sleepapnea hypopnea syndrome,OSAHS)患者寻找阻塞部位提供依据。该方法定位较准确,可重复性好,价廉,使用简便,已形成一整套标志和测量体系,在OSAHS的早期研究阶段就得到应用,从形态学上获得了对该病的大量认识,为探讨该病的发病机制,并指导临床的诊断和治疗发挥了重要作用。本文对该方法在OSAHS诊断、治疗中的应用和自身的局限性等问题做一综述。