中国汉族成人后牙区硬腭黏膜厚度测量及各组织学层次分布规律研究

目的 本文测量中国汉族人群中后牙区硬腭黏膜的厚度,分析其变化规律及相关因素,观察硬腭黏膜固有层结缔组织各组织学层次的厚度、特点及分布规律。方法 36例患者根据牙龈生物型（gingiva biotype）分为三组,使用骨探测法（bone sounding）测量由尖牙至第二磨牙腭侧共45个位点硬腭黏膜的厚度,采集牙周软组织增量手术中移植软组织修剪下来的剩余组织,筛选具有硬腭黏膜全层的样本,采用免疫组化技术,镜下观察结缔组织的组织学特点及分布规律。结果 硬腭黏膜平均厚度(3.52±1.02）mm、尖牙区为(3.26±0.81）mm、第一前磨牙区为(3.57±1.05）mm、第二前磨牙区为(3.72±1.04）mm、第一磨牙区为(3.33±0.96）mm、第二磨牙区为(3.73±1.11）mm;硬腭黏膜的厚度与性别、年龄无显著相关性,与牙龈生物型之间存在统计学差异;HE染色显示硬腭黏膜结缔组织层具有致密的胶原纤维,由第二前磨牙区域开始出现明显的黏膜下层,在第一磨牙区域多见疏松结缔组织,内含大量脂肪组织、血管、腺体等。结论 在中国汉族人群中硬腭黏膜厚度由尖牙向后逐渐增厚,在第一磨牙区变薄,向第二磨牙区再次变厚;在尖牙、第一前磨牙和第二磨牙区可见由龈缘向腭中缝处黏膜厚度逐渐变厚;硬腭黏膜固有层含有致密的结缔组织,由第二前磨牙区开始出现黏膜下层,含大量脂肪组织、血管、腺体等。     

Thickness of palatal masticatory mucosa associated with age.

BACKGROUND: The palatal masticatory mucosa is widely used as a donor material in periodontal plastic surgery. However, there are relatively few studies investigating the volume or thickness of the palatal mucosa. The purpose of this study was to determine the thickness of palatal masticatory mucosa in Asian subjects aged 14 to 59 years by a direct clinical technique. The associations of age and gender with the thickness of palatal mucosa were also examined. METHODS: Sixty-two systemically and periodontally healthy Asians (31 males; 31 females; age range 14 to 59 years) participated in this study. The younger age group (age 14 to 21 years) consisted of 32 subjects with a mean age of 16.8 years, whereas the older age group (age 30 to 59 years) consisted of 30 subjects with a mean age of 38.7 years. A bone-sounding method using a periodontal probe with minimal anesthesia and a prepared clear acrylic stent were utilized to assess the thickness of palatal mucosa at 15 measurement sites defined according to the gingival margin and mid-palatal line. Multiple linear regression analysis was performed to examine the associations of age and gender with the mean mucosal thickness at the subject level. The Wilcoxon test was used to determine the difference in mucosal thickness between the 2 age groups, and between gender at each measurement point. RESULTS: The mean thickness of palatal masticatory mucosa ranged from 2.0 to 3.7 mm. The younger age group had significantly thinner mucosa (mean 2.8 +/- 0.3 mm) than the older age group (mean 3.1 +/- 0.3 mm). Females had thinner mucosa than males in the same age group, but the difference was not statistically significant. Overall, the thickness of palatal mucosa increased from the canine to second molar areas and in the sites furthest from the gingival margin towards the mid-palate (with the exception of the first molar area, where significantly decreased thickness was observed). CONCLUSIONS: Within the limits of the present study, the canine and premolar areas appear to be the most appropriate donor site for grafting procedures in both young and adult individuals. The subepithelial connective tissue graft procedure can be considered as a treatment modality in young patients, since a sufficient volume of donor tissue can be obtained from the hard palate area. Other factors that may influence the thickness of palatal mucosa such as racial and genetic factors and body weight need to be further investigated.     

Connective tissue graft for gingival recession treatment: assessment of the maximum graft dimensions at the palatal vault as a donor site

BACKGROUND: The palatal masticatory mucosa is widely used as a connective tissue donor site in gingival recession treatment. However, concern has been raised regarding the potential risk of damaging the greater palatine artery (GPA) due to anatomical variations in the palatal vault. The anatomy of the palatal vault in terms of size and shape may affect the maximum dimensions of the graft that can be safely taken from the palatal vault. In a cohort of patients free of periodontal disease, the purpose of this study was to assess the maximum dimensions of the graft, particularly the height and length, that could be safely taken from the palatal vault. METHODS: Plaster impressions were made from 198 patients free of periodontal disease. Because the connective tissue graft is usually taken from an area extending from the mid-palatal aspect of the canine to the mid-palatal aspect of the second molar, this interval was measured and represented the maximum length dimension. The emergence of the GPA was assumed to be localized at the junction of the vertical and horizontal palatal walls of vault, and its course was marked on the plaster casts. The maximum height of the graft corresponded to the distances measured from the gingival margin to the marked course of the GPA of each tooth at its interproximal and mid-palatal aspects. RESULTS: The length of the maximum available tissue graft was 31.7 +/- 4.0 mm. The distance extending from the gingival margin to the greater palatine artery ranged from 12.07 +/- 2.9 mm at the canine level to 14.7 +/- 2.9 mm at the mid-palatal aspect of the second molar level. Therefore, in the premolar area, it was possible to harvest a connective tissue graft measuring 5 mm in height in all cases and 8 mm in height in 93% of cases. CONCLUSION: Our findings suggest that the maximum available tissue graft as measured in the palatal vault was large enough to allow a safe withdrawal from this donor site in a high percentage of our patient population free of periodontal disease.     

A new method to assess and measure palatal masticatory mucosa by cone-beam computerized tomography

Aim: The aim of this study was to apply a novel method to obtain high-quality images by cone-beam computerized tomography (CBCT) that consistently allowed the determination of the dimensions of the palatal mucosa.
Materials and Methods: Thirty-one patients participated in this study. At the time of the CBCT scanning, the patients wore a plastic lip retractor and wooden spatulas to retract soft tissues away from the teeth and gingiva. The thickness of the palatal mucosa was obtained at forty different locations on each patient.
Results: Retraction of the lips and cheek allowed a clear observation and measurements of the thickness of the palatal masticatory mucosa. The average thickness of the palatal mucosa was 2.92 mm in the canine area, 3.11 mm at the first pre-molar, 3.28 mm at the second pre-molar, 2.89 mm at the first molar and 3.15 mm at the second molar. Statistical differences were observed at different ages and heights of measurements.
Conclusions: A new non-invasive method to consistently obtain high-quality images of the palatal masticatory mucosa is described. Measurements of this mucosa could be obtained at different locations on the palate.     

Masticatory mucosa in subjects with different periodontal phenotypes

AIMS: The aim of the present investigation was to study thickness of masticatory mucosa and gingival width in subjects with different periodontal phenotypes. METHODS: Periodontal phenotypes were defined with the aid of cluster analysis of standardised parameters including mean gingival thickness and width as well as ratio of crown width to its length at maxillary canines, lateral and central incisors of 40 young adults with healthy periodontal conditions. RESULTS: 3 groupings could be observed. Clusters A1 and A2 comprised 75% of all subjects. They were characterised by thin gingiva and a slender tooth form. Clusters A1 and A2 were differentiated by gingival width. Cluster B comprised 11 subjects with relatively thick and wide gingiva and a quadratic tooth shape. In general, characteristics of the frontal sextant in the maxilla were also found in other parts of the dentition. Thus, mean thickness of masticatory mucosa as well as gingival width and crown form differed significantly among clusters. In addition, cluster B subjects had a significantly greater mean periodontal probing depth. Multiple linear regression analysis was employed to identify significant factors influencing palatal mucosal thickness. Women had considerably thinner palatal mucosa than men. Furthermore, cluster affiliation had a significant influence on thickness of palatal mucosa. Thickest tissue was found in the premolar region, whereas the mucosa over the root prominence of the first molar represented an anatomical barrier for graft harvesting. CONCLUSIONS: Thickness of masticatory mucosa strongly depends on gender and the periodontal phenotype.     

Soft tissue thickness for placement of an orthodontic miniscrew using an ultrasonic device

OBJECTIVES: To evaluate area- and gender-related differences in the soft tissue thickness of potential areas for installing miniscrews in the buccal-attached gingiva and the palatal masticatory mucosa. MATERIALS AND METHODS: The sample consisted of 61 Korean young adults. An ultrasonic gingival-thickness meter was used to measure the soft-tissue thickness in the buccal-attached gingiva just adjacent to the mucogingival junction of the upper and lower arches and 4 mm and 8 mm below the gingival crest in the palatal masticatory mucosa. Independent t-test, paired t-test, and one-way analysis of variance were used for statistical analysis. RESULTS: Buccal-attached gingiva thickness in the upper arch was significantly greater in men than in women, but buccal-attached gingiva thickness in the lower arch and palatal masticatory mucosa thickness 4 and 8 mm below the gingival crest did not show gender differences. Significantly thicker soft tissue occurred in the anterior areas in the upper arch and in the posterior areas in the lower arch. In the palatal masticatory mucosa, significantly thicker soft tissue was found 4 mm below the gingival crest in the anterior areas and 8 mm below the gingival crest in the posterior areas. The areas between the canines and the premolars showed higher values than other areas 4 mm below the gingival crest. However, the soft-tissue thickness 8 mm below the gingival crest showed a progressive increase from the anterior to the posterior areas. CONCLUSION: Measurements of the soft-tissue thickness using an ultrasonic device could help practitioners select the proper orthodontic miniscrew in daily clinical practice.     

Immediate postexpansion changes following the use of the transpalatal distractor.

PURPOSE: This study analyzed the immediate postexpansion positional changes of the maxillary halves resulting from the use of the transpalatal distractor (Surgi-Tec NV, Bruges, Belgium). PATIENTS AND METHODS: Corticotomies were performed in the same way as surgically assisted rapid palatal expansion, all from a buccal sulcus approach. Titanium abutment plates with box extension were placed horizontally in the vertical wall of the palatal vault overlying the second premolar root through a mucoperiosteal incision and fixed with titanium screws 5 mm in length. An appropriate telescopic distraction module was fitted in the slots of the boxes. Expansion started 1 week after surgery, at a rate of 0.33 mm/d. Digital measurements on digital photographs of the models were obtained from 20 postadolescent patients before and immediately after transpalatal distraction. The distractor was placed at the level of the second premolar. Pterygomaxillary separation was not performed. Changes in the intercanine, interpremolar and intermolar width, in the dental arch perimeter, and in the premolar and molar angulations in the frontal plane were analyzed and correlated. RESULTS: Width expansions of 35.7%, 31.7%, and 22.7% were noted in the canine, premolar, and molar regions, respectively. There was a mean increase of the arch perimeter of 10.5%, which correlated well (P <.001) with the expansion at the canine and premolar level. The mean angulation changes in the frontal plane of the premolar and molar segments were minimal, -8.3 degrees +/- 9.6 degrees and 0.9 degrees +/- 9.9 degrees, respectively. The change in angulation at the molar level correlated (P <.005) with the amount of expansion in that region. Premolar angulation did not correlate with the expansion, and segment angulation did not correlate with age. CONCLUSIONS: The expansion at the canine level was 1.5 times greater than at the molar level (corrected value relative to the original intermolar width). The change in arch perimeter can be predicted from the expansion at the canine and premolar level. Expansion in the frontal plane occurs with little tipping of the segments.     

Maxillary molar distalization with a bone-anchored pendulum appliance

To obtain an effective and compliance-free molar distalization without an anchorage loss, we designed the bone-anchored pendulum appliance (BAPA). The aim of this study was to evaluate the stability of the anchoring screw, distalization of the maxillary molars, and the movement of teeth anterior to maxillary first molars. The study group comprised 10 patients (mean age 13.5 +/- 1.8 years) with Class II molar relationship. A conventional pendulum appliance was modified to obtain anchorage from an intraosseous screw instead of the premolars. The screw was placed in the anterior paramedian region of the median palatal suture. Skeletal and dental changes were measured on cephalograms, and dental casts were obtained before and after distalization. A super Class I molar relationship was achieved in a mean period of 7.0 +/- 1.8 months. The maxillary first molars distalized an average of 6.4 +/- 1.3 mm in the region of the dental crown by tipping distally an average of 10.9 degrees +/- 2.8 degrees . Also, the maxillary second premolar and first premolar moved distally an average of 5.4 +/- 1.3 mm and 3.8 +/- 1.1 mm, respectively. The premolars tipped significantly distally. No anterior incisor movement was detected. The BAPA was found to be an effective, minimally invasive, and compliance-free intraoral distalization appliance for achieving both molar and premolar distalization without any anchorage loss.     

Thickness of masticatory mucosa

BACKGROUND: The aim of the present study was to assess thickness of all parts of the masticatory mucosa by using an ultrasonic measuring device. METHODS: A total of 40 periodontally healthy subjects, 19 to 30 years old, took part. Thickness of masticatory mucosa was measured at a maximum of 149 sites in each proband. RESULTS: Female volunteers had significantly thinner mean masticatory mucosa than males (p<0.01). Mean thickness of facial gingiva ranged between 0.7 mm at canines in the maxilla and central incisors in the mandible and 2.3 mm at 3rd molars in the mandible. In the mandible, thickness of lingual gingiva ranged between 0.9 mm at lateral incisors and 2.3 mm at 3rd molars. Interdental gingiva ranged between 1.0 mm 2.1 mm. With 3 mm or more, on average, palatal masticatory mucosa was thickest in the 3rd molar region and at 2nd premolars at more central locations. 2 regions with comparatively thin palatal mucosa of about 2 mm were identified, namely (i) at central and lateral incisors and (ii) at the prominence of the palatal roots of 1st and 2nd molars. The thickest tissue with more than 4 mm, on average, was observed in the tuberosity and retromolar regions. CONCLUSIONS: Considerable intra- as well as interindividual variation of thickness of masticatory mucosa could be observed. According to differences in thickness of facial and interdental gingiva, it appears that lining is also an important function of the gingiva in reducing and smoothing the pronounced convexities of the dentoalveolar, i.e., skeletal, complex.     

B-mode versus A-mode ultrasonographic measurements of mucosal thickness in vivo.

OBJECTIVE: The objective of this study was to compare the measurement accuracy of A-mode and B-mode ultrasonographic assessments of palatal masticatory mucosal thickness in vivo. STUDY DESIGN: Thickness of palatal masticatory mucosa in the molar region of 50 volunteers was measured once with a B-mode ultrasound device (10 MHz) combined with a standoff for intraoral applications. At identical reading points thickness was also assessed with an A-mode device (5 replicates) and by needle probing for determination of true thickness. RESULTS: On average true thickness ranged between 2.9 and 3.3 mm (95% confidence intervals; median, 3.1 mm). B-mode ultrasonography overestimated truth by 0.19 mm (median) and differed significantly from truth (P =.008), whereas A-mode ultrasonography slightly underestimated true thickness by -0.05 mm (median). Limits of agreement were wider for A-mode ultrasonography (2.00 mm) than for B-mode ultrasonography (0.88 mm). CONCLUSIONS: Because accuracy of 0.2 mm is acceptable for many clinical indications, B-mode and A-mode yield sufficient accuracy for measurements of mucosal thickness.     

Ultrasonic determination of thickness of masticatory mucosa: a methodologic study.

OBJECTIVE: The aim of the present study was to assess the reliability and validity of ultrasonic measurements of thickness of the masticatory mucosa. STUDY DESIGN: Eleven periodontally healthy subjects took part. Thickness of the buccal gingiva was assessed midbuccally and interdentally. In the maxilla, the palatal mucosa was measured at every tooth midpalatally, between the first and second molars, and between the second and third molars at each of 3 defined locations 4 mm apart. In the mandible, thickness of the lingual gingiva was measured midlingually as well as interdentally between the first and second molars and between the second and third molars. Thickness of the retromolar mucosa was also assessed. All 1,293 measurements were repeated after 24 hours. Validity of measurements was tested in a porcine model. RESULTS: Mean (+/- standard deviation) thickness of the midbuccal and midlingual gingiva was 0.99+/-0.52 mm; the measurement error was 0.26 mm. Measurements were well correlated (Pearson's r = .74, P<.001). Mean thickness of the papillary gingiva was 1.19+/-0.53 mm; the measurement error was 0.37 mm (r = .58, P<.001). A lower reliability was observed for palatal measurements of mucosal thickness; mean thickness was 2.36+/-0.87 mm, and measurement error was 0.54 mm (r = .64, P<.001). The validity of measurements was excellent in the 0.5-4.5 mm range. CONCLUSIONS: Differences in reliability of ultrasonic assessments of mucosal thickness in different parts of the oral cavity may depend on the difficulties of repeatedly measuring at the same location, on varying thickness of the tissues, and on expression of palatal rugae. These problems might be resolved by averaging multiple measurements.     

腭部不同微种植体植入位置的骨质情况研究

目的:研究腭部骨质情况,提供腭部微种植植入参考图。方法:硬腭部测量时,纳入148例研究对象;腭侧牙槽骨测量时,筛选出其中的86名研究对象,使用CBCT分别测量其骨质情况。结果:硬腭部的骨质厚度在前磨牙间冠状面处最大;腭侧牙根间间距随着远离牙槽嵴顶而逐渐增加。结论:硬腭部微种植体植入部位推荐在前磨牙间冠状面植入。腭侧牙槽骨前牙区推荐在侧切牙与尖牙间距离牙槽嵴顶6 mm以上水平植入;前磨牙区推荐在距离牙槽嵴顶4 mm以上水平植入;磨牙区推荐斜形植入,高于牙槽嵴顶8 mm时需注意上颌窦的影响。     

汉族青年牙周健康人群上颌磨牙腭侧牙槽嵴骨突的CBCT研究

目的:研究汉族青年牙周健康人群中上颌腭侧牙槽嵴骨突的分布、位置及表面黏膜厚度.方法:采用CBCT观察245名受试者上颌第一磨牙至第三磨牙腭侧牙槽嵴骨突的分布,并测量骨突顶点距对应磨牙CEJ的距离和表面最薄处黏膜厚度.结果:245名受试者中在上颌第一、第二和第三磨牙腭侧牙槽嵴骨突的发现率分别为2.45％、31.22％和2...     

"Safe zones": a guide for miniscrew positioning in the maxillary and mandibular arch

The aim of this study was to provide an anatomical map to assist the clinician in miniscrew placement in a safe location between dental roots. Volumetric tomographic images of 25 maxillae and 25 mandibles taken with the NewTom System were examined. For each interradicular space, the mesiodistal and the buccolingual distances were measured at two, five, eight, and 11 mm from the alveolar crest. In this article, measurements distal to the canines are presented. In the maxilla, the greatest amount of mesiodistal bone was on the palatal side between the second premolar and the first molar. The least amount of bone was in the tuberosity. The greatest thickness of bone in the buccopalatal dimension was between the first and second molars, whereas the least was found in the tuberosity. In the mandible, the greatest amount of mesiodistal dimension was between first and second premolar. The least amount of bone was between the first premolar and the canine. In the buccolingual dimension, the greatest thickness was between first and second molars. The least amount of bone was between first premolar and the canine. Clinical indications for a safe application of the miniscrews are provided, as well as the ideal miniscrew features.     

Accuracy of oral mucosal thickness measurements using spiral computed tomography

Background: Assessment of oral mucosal thickness is important in implant surgery; however, examining the soft tissue three dimensionally is difficult. A reamer method is invasive, and a non‐invasive ultrasonic method produces only low‐resolution images depending on anatomic variations. The emerging technology of spiral computed tomography (CT) is an alternative to the conventional methods. Spiral CT has been a useful diagnostic tool in implant surgery. Although it delivers high radiation doses, spiral CT provides three‐dimensional imaging of low‐contrast structures. The purpose of the present study is to assess the accuracy of oral mucosal measurements using spiral CT. Methods: Thickness of maxillary oral mucosa was measured in five cadavers. The measurement sites were set up in buccal, palatal, and middle of the crest in the missing tooth area in the incisor, canine, premolar, and molar regions. Each cadaver was exposed to spiral CT after installing the measurement guide. After that, each site was physically measured by reamer. Linear regression and correlation analysis were performed to describe the association between radiographic and physical measurements. Results: A total of 114 measurements were performed with statistical analyses. Mean values and standard deviations of physical and radiographic measurements were 3.12 ± 1.43 and 2.83 ± 1.70 mm, respectively. The radiographic and physical measurements demonstrate strong correlation (r = 0.90; P <0.01). Measurement error was 0.52 ± 0.36 mm. According to the regions, the measurements in buccal, palatal, and missing tooth region depicted a significant correlation (r = 0.92, r = 0.85, and r = 0.91, respectively). The boundary of the bone and mucosa was indistinguishable at 23 buccal sites. Twenty‐three measurements that could not be distinguished with CT had a mean of 0.69 and standard deviation ± 0.13 mm. Conclusions: The correlation between spiral CT and physical measurement was high except in sites of very thin mucosa. Spiral CT can be considered an alternative method for the measurement of oral mucosal thickness. Because of the higher radiation exposure, caution should be exercised and radiation dosage versus clinical benefit assessment is required.     

基于腭部骨质厚度测量的CBCT与头颅侧位片的对比研究

目的：研究头颅侧位片与CBCT测量腭部骨质厚度的差别。材料与方法：收集30名患者的CBCT数据及头颅侧位片影像,应用CBCT及头颅侧位片,测量矢状向上从第一二前磨牙之间到第一第二磨牙之间不同间隔区域处的腭部骨质厚度,应用CBCT在冠状向上测量距腭中缝1.5 mm到距腭中缝10 mm之间不同间隔区域处的腭部骨质厚度,重复测量以探究不同测量方法之间的差异。结果：应用CBCT测量距腭中缝5 mm处的腭部骨质最薄;在矢状向上所有区域的测量值中,测量距腭中缝5 mm处的腭部骨质厚度,应用CBCT及头颅侧位片两者的结果无统计学差异;在第二前磨牙与第一磨牙之间（P2M1）到第一磨牙与第二磨牙之间（M1M2）的不同间隔区域处的测量值中,测量距腭中缝1.5 mm的腭部骨质厚度,应用CBCT所得的测量值大于头颅侧位片的测量值。结论：在所有测量的区域中,距腭中缝5 mm处的骨质最适宜用于描述腭骨轮廓。     

上颌窦底提升术相关的应用解剖学研究

目的：为临床上颌窦底提升术的实施提供解剖学依据及数据参考。方法：在经福尔马林固定的成人尸头标本和上颌骨标本上,对上颌后区牙根、牙龈缘（牙槽嵴未吸收）至上颌窦底距离和吸收牙槽嵴至上颌窦底距离进行观测（其中固定标本均为粘膜厚度计入测量）。结果：固定标本上颌窦底至吸收牙槽嵴黏膜前、中、后距离分别为（13．13±0．74）ram、（8．80±3．58）mm、（12．67±2．38）mm,上颌窦底长为（22．70±3．80）mm。牙槽嵴未吸收固定标本第三磨牙、第二磨牙、第一磨牙、第二前磨牙、第一前磨牙牙龈缘至窦底的距离分别为（14．50±3．50）ram、（12．58±3．31）mm、（13．05±2．85）ram、（16．40±3．73）mm、（18．95±4．05）mm。上颌骨标本上颌窦至吸收牙槽嵴前、中、后距离分别为（10．33±1．40）mm、（7．89±1．50）mm、（9．89±1．42）mm。牙槽嵴未吸收上颌骨标本第三磨牙、第二磨牙、第一磨牙、第二前磨牙牙根距上颌窦底高度分别为（2．55±1．65）mm、（3．40±0．50）ram、（2．45±0．15）mm（m、（3．05±0．55）mm。牙槽嵴未吸收上颌骨标本第三磨牙、第二磨牙、第一磨牙、第二前磨牙牙槽嵴距上颔窦底高度分别为（9．23±2．02）mm、（10．83±2．00）mm、（10．93±2．02）mm、（14．20±1．40）mm。结论：通过对口腔上颌窦解剖学数据的观测,能够为上颌窦底提升术提供形态学数据参考。     

A long-term study of transverse stability of maxillary teeth in patients with unilateral complete cleft lip and palate

summary The aim of this study was to investigate the long term post-treatment transverse stability of the maxillary dental arch in subjects with unilateral complete cleft lip and palate (UCLP) treated by the Harvold/Bøhn method of orthodontic expansion and prosthodontic retention. The treatment of 22 consecutive patients, primarily operated on during the period 1957–60, was completed at a mean age of 18.1 years by the provision of a fixed partial retention prosthesis across the cleft using the cleft side central incisor and canine only as abutment teeth. The cleft side lateral incisor was missing in each case. Dental casts were made at the time of abutment preparation and at six subsequent times with the final observation 13·5 years after treatment completion. Measurements of any shift in the transverse position of cleft side and non-cleft side canines, premolars and first molars were made on standardized photographs of the casts. A constructed antero-posterior palatal line served as 'midline' reference. A mean reduction of width at the final observation, as recorded from the palatal surface to the reference line, was for the cleft side canine: −0·4 mm, the premolar immediately distal to the prosthesis and the first molar: both −1·2 mm. The corresponding mean width reductions on the noncleft side were: canine −0·9 mm, premolar −1·2 mm, first molar −1·6 mm. The rate of movement towards the midline decreased linearly with in(time) for all variables (P < 0·02) but for the cleft side canine.     

牙齿几何外形和模型底座厚度对隐形矫治器厚度的影响

目的研究牙齿几何外形和模型底座厚度对热成型隐形矫治器厚度的影响。方法层析扫描标准上颌模型,形成数字图像,通过数字化三维图像处理,激光快速成型输出底座厚度分别为0、1、2、3、4、5、6、7、8、9、10 mm的树脂模型共11副,在每个树脂模型上通过热压膜成型制作10副矫治器,标记每副矫治器上14个牙位的唇颊面和舌腭面牙冠面轴点,使用千分尺测量牙冠面轴点处矫治器的膜片厚度,比较热压膜成型后不同牙位上隐形矫治器的厚度,分析厚度分布规律。结果底座厚度为0 mm时,隐形矫治器中切牙到第二磨牙唇颊面厚度从0.398 mm均匀递增到0.504 mm,坐标图表现为均匀递增的直线,膜片厚度随牙位变化的直线公式为y=0.019x+0.379,拟合度和相关性良好。尖牙腭面膜片厚度最大,第一磨牙腭面膜片厚度大于第二前磨牙,表现为S形曲线。不同底座厚度的树脂模型上热成型的矫治器唇颊面和舌腭面膜片厚度随牙位变化的规律基本相同。隐形矫治器唇颊面和舌腭面的膜片厚度随模型底座厚度的增加呈递减趋势。结论隐形矫治器唇颊面厚度从前牙到后牙均匀递增;矫治器腭面厚度以尖牙最厚,分布无明显规律。模型底座厚度对隐形矫治器厚度有影响。     

Relationship between pattern of masticatory path and state of lateral occlusal contact

Summary  The purpose of this study is to clarify whether the state of occlusal contact on lateral excursion is related to the pattern of masticatory movement path. The masticatory movement during mastication of softened chewing gum and the occlusal contact on lateral sliding of the mandible by 1 mm (L1), 2 mm (L2) and 3 mm (L3) were recorded in 50 healthy subjects. The path of masticatory movement was classified into one of seven patterns. The number of teeth involved in the occlusal contact in each pattern was investigated and compared among different lateral occlusal positions. The occlusal contact was then classified into 15 types based on one or a combination of the following four regions; incisal region, canine region, premolar region and molar region. The number of occlusal contact type for each pattern was investigated and compared among patterns. The number of teeth involved in occlusal contact decreased as the degree of lateral excursion increased, and significant differences were observed among the lateral occlusal positions ( P  < 0·001). The occlusal contact tended to decrease in the molar region and increase in the canine or premolar regions as the degree of the lateral excursion increased. When comparing among patterns, significant differences were observed at L2 and L3 (L2; P  < 0·001, L3; P  = 0·030) but not at L1 ( P  = 0·318). The difference was remarkable at L2. It was suggested that the state of occlusal contact at L2 and L3, particularly at L2 was related to the masticatory path pattern.