A new, accurate and fast digital method to predict unerupted tooth size

The sum of the lower incisor tooth width has been proposed as the best predictor for calculating unerupted canine and premolar mesiodistal tooth sizes. The aims of this study were to develop a new, fast, and accurate computerized method to predict unerupted mesiodistal tooth sizes and to determine which reference tooth or combination of reference teeth was the best predictor for canines and premolars in a Spanish sample. The dental casts of 100 Spanish adolescents with permanent dentition were measured to the nearest 0.05 mm with a two-dimensional computerized system. The goal was to predict unerupted canine and premolar mesiodistal tooth sizes using the sizes of the upper central incisor, upper and lower first molar, or a combination of these as a reference and using a specific mesiodistal tooth-size table. The results showed that the Digital Method proposed was very accurate in predicting unerupted canine and premolar tooth size. The combination of the sums of the permanent upper central incisor and the lower first molar was the best predictor for canines and premolars in this sample. Upper arch teeth were better predicted than lower arch teeth. The upper lateral incisor provided the worst predictions.     

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.     

Orthodontic Space Closure without Contralateral Extraction through Mesial Movement of Lower Molars in Patients with Aplastic Lower Second Premolars

METHOD AND PATIENTS: A method is presented that allows unilateral space closure in patients with aplastic lower second premolars. Based on a straight-wire appliance, space closure was achieved with a combination of "push mechanics" using the second molar as an anchorage unit and Class II "pull mechanics", thus avoiding the application of any distalizing force on the lower incisors. The results from 13 consecutively treated subjects (five boys, eight girls, mean age 12 years and 6 months) were analyzed. RESULTS: Complete bodily space closure was achieved in all 13 cases within a mean treatment time of 2 years and 7 months. The desired Angle Class III molar relationship of one premolar width (+/- 1/4 premolar width) on the aplastic side was successful in eleven patients, an additional 4.7 mm of space being created for the third molar on the aplastic side compared with the contralateral side (p < or = 0.01). However, adverse effects could be kept to a minimum, with no method-dependent side effects being recorded with regard to canine and molar relationships on the contralateral side, or to overbite, overjet, or upper and lower incisor inclination. The mean lower midline shift of 0.8 mm was in accordance with the mean distal canine relationship of 1/3 premolar width on the aplastic side. CONCLUSION: These results confirm that orthodontic space closure in cases of unilateral aplastic lower second premolars can be performed successfully with the presented treatment method without the need for additional premolar extractions, prosthodontic treatment or implants. Furthermore, the prognosis for the lower wisdom tooth on the aplastic side is improved.     

Thickness of posterior palatal masticatory mucosa: the use of computerized tomography

BACKGROUND: Periodontal plastic surgery is used to fulfill the esthetic and functional demands of patients. The palatal masticatory mucosa is the main donor site for connective tissue, and the thickness of the graft tissue obtained is an important factor for the success of this technique. The aim of this study was to measure the thickness of masticatory mucosa in the posterior palatal area using computerized tomography (CT). METHODS: The thickness measurements were performed on the images of 100 adult subjects who underwent CT on the maxilla for implant surgery. Twenty-four standard measurement points were defined in the hard palate according to the gingival margin and the middle palatal suture. The radiographic measurements were used after calibration. The data were analyzed to determine the differences in the mucosal thickness according to gender, age, tooth position, and depth of the palatal vault. RESULTS: The overall mean thickness of the palatal masticatory mucosa was 3.83 +/- 0.58 mm (range: 2.29 to 6.25 mm). Females had significantly thinner mean masticatory mucosa (3.66 +/- 0.52 mm) than males (3.95 +/- 0.60 mm) (P <0.0001). The thickness of the palatal masticatory mucosa increased with age. The mean thickness according to tooth site was 3.46 mm (maxillary canine), 3.66 mm (first premolar), 3.81 mm (second premolar), 3.13 mm (first molar), 3.31 mm (the base of the interproximal papilla of the first and second molars), and 3.39 mm (second molar). There was an overall increase in the thickness of the palatal masticatory mucosa as the distance from the gingival margin to the middle palatine suture increased, with the exception of the Ca-d (a point at 12 mm from the gingival margin of the canine) region. There was no significant difference in the thickness of the palatal masticatory mucosa between the groups with high or low palatal vaults. CONCLUSIONS: The palatal masticatory mucosa thickness increased from the canine to premolar region but decreased at the first molar region and increased again in the second molar region, with the thinnest area at the first molar region and the thickest at the second premolar region. The canine to premolar region seems to be the most appropriate donor site that contains a uniformly thick mucosa. CT can be considered an alternative method for the measurement of palatal soft tissue thickness.     

自锁托槽对唇腭裂腭扩展短期效果的研究

目的：探讨自锁托槽对单侧完全性唇腭裂患者上颌腭扩展的短期治疗效果。方法选取5例恒牙期单侧完全性唇腭裂（UCLP）患者,未行牙槽突裂骨移植手术,上颌牙齿粘贴自锁托槽（AO, Time2）,放置高弹性镍钛弓丝,采集患者治疗前和腭扩展6~17个月后的牙颌模型、头颅定位后前位片进行测量,分析上颌腭扩展前后患者的牙弓、牙槽骨、腭穹窿以及颌骨的形态变化。结果牙颌模型测量结果提示：第一前磨牙区牙弓宽度明显增大,其次为尖牙区牙弓宽度,第一磨牙区牙弓宽度增加最少,第二磨牙区宽度减小。牙弓长度变化不明显。第一磨牙近中颊向扭转。腭部宽度增加,深度减小。头影测量结果提示：鼻腔宽度、上颌基骨宽度和上颌磨牙宽度稍有增加。结论唇腭裂自锁托槽腭扩展后上颌牙颌形态在横向宽度的变化较矢状向的变化明显。短期腭扩展治疗效果以牙齿移动和牙槽改建为主。     

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。     

Morphology of the palatal vault of primary dentition in transverse view

The purpose of this study was to investigate the transverse view of the morphology of the palatal vault in the primary dentition at the primary second molar level. Observations were obtained from 150 dental stone casts of normal children (78 boys and 72 girls; aged four to five years). Palatal width, palatal depth, arch width, and primary second molar angulation were measured. There were no significant differences in palatal depth and primary second molar angulation between boys and girls or between the right and left sides. However, girls had a statistically significantly narrower upper dental arch width and palatal width than did boys. Palatal widths on the left side were statistically significantly larger than those on the right side for both sexes. Asymmetry in the palatal width greater than two mm was present in 21.8% of boys and 16.7% of girls. There was a correlation between buccal tipping in the upper primary second molar and greater palatal width.     

Marginal fit of 14-unit zirconia fixed dental prosthesis retainers

Summary  The marginal fit of 14-unit fixed dental prosthesis retainers and single-crown copings fabricated by the same computer-aided design (CAD)/computer-aided manufacturing (CAM) system were evaluated in vitro hypothesizing that the marginal opening might be independent of the type of restoration. Eight ivorine maxillary teeth (FDI locations 27, 25, 23, 21, 11, 13, 15 and 17) were prepared to accommodate a 14-unit prosthesis. Ten fixed dental prosthesis retainers and 40 single-crown-copings were fabricated using Zeno CAD/CAM on 20 master dies. Four cross-sections were made from each tooth and the marginal gap dimensions were measured. One-way anova was used to test the difference between the experimental groups and two-way anova and a post hoc test (Student–Newman–Keuls) were carried out to determine the influence of the location of the abutment tooth and the measurement location within the abutment tooth in the experimental groups ( P  < 0·05). Mean marginal gap dimensions and standard deviations for fixed dental prosthesis retainers and single-crown copings were 25 ± 29 and 13 ± 12 μm, respectively. The type of restoration showed a significant influence ( P  < 0·001) on the marginal gap. The location of the abutment tooth ( P  < 0·001) and the measurement location ( P  < 0·001) exhibited significant influence on marginal gaps of fixed dental prosthesis retainers while no influence on single-crown copings could be detected. The highest marginal gaps were found at the palatal surface of the incisor and canine of the 14-unit fixed dental prosthesis retainers. Fourteen-unit fixed dental prosthesis showed significantly higher marginal openings than single crowns fabricated under the same conditions. However, both restorations showed clinically acceptable marginal openings.     

Movement of abutment teeth in spring cantilever bridges: a laboratory study

The extent and directions of movements of spring bridge abutments were studied on acrylic casts with resilient steep and shallow palates and containing human molar and premolar abutments with compressible ‘periodontal ligaments’. Bridges with rigid bars and ‘flexible’ standard, long and short lengths were cast in Type IV gold, and soldered to Type III gold retainers which were pinned to the abutments. The pontic on each bar was depressed a standard 0.2 mm, and the movement of the abutments registered on a dial gauge resting against the mesio-buccal corner of each retainer. The combination of bar length and palatal contour causing least movement of an abutment was the shortest bar to the molar abutment in the shallow palate model; indeed all bars on this model deflected the molar abutment less than similar bars on the steep palate model. Differences in palatal contours did not affect the extent of movements of the premolar abutments which were comparable to molar movements in the steep palate model. Abutment teeth moved mesio-buccally when the pontic was depressed, and the elbow of the bar usually moved off the palate indicating the fulcrum was positioned along the anterior section of the bar.     

Dental arch width stability after quadhelix and edgewise treatment in complete unilateral cleft lip and palate

OBJECTIVE: To evaluate the transverse stability of the dental arch in unilateral cleft lip and palate (UCLP) patients after orthodontic treatment with quadhelix and edgewise appliances. MATERIALS AND METHODS: Twenty repaired complete UCLP patients with posterior crossbites were chosen as the study subjects. All had ceased retention at least 15 months previously. Measurements were carried out directly on the pretreatment, posttreatment, and postretention study models using a three-dimensional dental cast analyzer. The interdental widths were measured for the canines, first premolars, second premolars, first molars, basal bone, and the alveolar arch. Two-way analysis of variance and Fisher's LSD was performed in comparing the difference between intervals. RESULTS: Lower inter-first-premolar width and upper arch widths of each region increased significantly (P < .05) after orthodontic treatment. The expansion was greater in the anterior than the posterior region in the upper arch, and the greatest increase was in the upper first premolar region. The upper arch width decreased after retention, with the decrease of the arch width in the upper canine (1.3 +/- 0.8 mm) and first premolar (1.5 +/- 0.8 mm) regions being statistically significant. The increased upper arch width in each region and the lower inter-first-premolar width maintained significant expansion after retention. CONCLUSIONS: The widths of the dental arch increased significantly after expansion with a quadhelix followed by preadjusted edgewise treatment. Relapse occurred, especially in the upper canine and first premolar region, but most of the treatment effect on the upper arch remained after retention.     

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.     

AngleⅡ类错(牙合)畸形患者牙弓宽度的测量分析

目的：比较分析AngleⅡ类错[牙合]畸形患者牙弓宽度及其牙弓形态特点。方法：选择AngleⅡ^1类错[牙合]畸形患者（平均年龄15．6岁）、AngleⅡ^2类错[牙合]畸形患者（平均年龄15．8岁）和对照组AngleⅠ类轻度错[牙合]畸形患者（平均年龄16．2岁）的原始模型各40副,测量每副模型的上下尖牙、第一前磨牙、第二前磨牙、第一磨牙之间的距离,计算上、下颌对应牙弓宽度差;对各组各项牙弓宽度和牙弓宽度差进行t检验。结果：AngleⅡ^1类错[牙合]畸形患者上颌牙弓宽度较AngleⅠ类轻度错[牙合]畸形患者狭窄,但差异无显著性（Jp〉0．05）,AngleⅡ^1类错[牙合]畸形患者下颌牙弓宽度与AngleⅠ类轻度错[牙合]畸形患者无显著差异（P〉0．05）;AngleⅡ^2类错[牙合]畸形患者上颌中、后牙弓宽度和下颌牙弓宽度较AngleⅠ类轻度错[牙合]畸形患者的牙弓宽度窄,差异有显著性（P〈0．05）;AngleⅡ^1类错[牙合]畸形患者下颌牙弓宽度比AngleⅡ^2类错[牙合]畸形患者下颌牙弓宽大,差异有显著性（P〈0．05）;AngleⅡ^1类错[牙合]畸形患者上下颌宽度差小于AngleⅠ类轻度错[牙合]畸形患者,尖牙、第二前磨牙处差异有显著性（P〈0．05）;AngleⅡ^2类错[牙合]畸形患者上下颌牙弓宽度差与AngleⅠ类轻度错[牙合]畸形患者无显著差异（P〉0．05）;AngleⅡ^1类错[牙合]畸形患者上下颌牙宽度差比AngleⅡ^2类错[牙合]畸形患者小,尖牙处宽度差差异有显著性（P〈0．05）。结论：AngleⅡ^1、AngleⅡ^2错[牙合]畸形患者上颌牙弓以及AngleⅡ^2错[牙合]畸形患者下颌牙弓宽度发育均有不足．治疗中可适当进行扩弓。     

Effect of non-working occlusal contacts on vertical condyle position

Summary  The presence of non-working occlusal contacts is often considered harmful for the temporomandibular joint. Thus, the purpose of this study was to investigate the effect of non-working occlusal contacts on the condylar position during submaximal and maximal clenching. The study comprised 22 healthy subjects having a canine-guided occlusion. None of them had a third molar and none of them had a missing tooth or showed tooth mobility. All subjects clenched on (i) the canine, (ii) the canine while a stiff bite registration material was positioned between the second premolar and the first molar on the non-working side. The clenching level was controlled by surface electromyography of the masseter muscle. During clenching, the vertical and horizontal condylar position was predicted using six degrees of freedom ultrasonic motion analyser. Clenching on the canine caused a cranial movement of the non-working side condyle. This movement was reduced by 0·6–0·9 mm when the subjects clenched while the artificial non-working side contacts were in place. These results indicate that the contacts on the non-working side may be able to prevent upward joint movement.     

Space conditions and dental and occlusal features in patients with palatally impacted maxillary canines: an aetiological study

The aetiology of palatal canine impaction is unclear. The aim of this research was to investigate the occlusal features that could contribute to the aetiology of palatal maxillary canine impaction. The material consisted of the pre-treatment dental casts of 34 patients (27 female and seven male) with unilateral palatal canine impaction (impaction group). The average age of this group was 17.7 years (+/- 4.6). These were matched according to age, gender and type of malocclusion with a comparison group of pre-treatment dental casts from unaffected orthodontic patients. From the dental casts the following parameters were obtained: (1) dentoalveolar arch relationship, (2) missing or anomalous teeth, (3) the mesiodistal width of each maxillary tooth, (4) the upper arch perimeter, (5) the maxillary inter-premolar and inter-molar widths. The arch length-tooth size discrepancy was only calculated for subjects with no missing teeth. Palatal canine impaction occurred most frequently in subjects with a Class II division 2 malocclusion. There was an association between palatal canine impaction and anomalous lateral incisors (P = 0.01). The transverse arch dimension was significantly wider in the impaction group than in the comparison group (P < 0.01). There was no statistically significant difference in the mesiodistal width of maxillary teeth or in the arch length-tooth size discrepancy between the palatal canine impaction group and their matched comparisons (P > 0.05). These results suggest that the presence of an 'excess palatal width' and anomalous lateral incisor may contribute to the aetiology of palatal canine impaction.     

Dental arch morphological and dimensional characteristics in Jordanian children and young adults with beta-thalassaemia major

OBJECTIVE: The aim of this study was to examine the arch dimensions of Jordanian patients with beta-thalassaemia major in comparison with an unaffected control group. METHODS: The sample consisted of 24 patients who suffered from beta-thalassaemia major (mean age = 13.9 +/- 3.1 years) and an unaffected control group (mean age = 13.5 +/- 2.9 years) matched for dental age, sex, and incisor and molar relationships. The unaffected control group was randomly selected from four public schools in the Governate of Irbid-Jordan. Alginate impressions were taken of the maxillary and mandibular dental arches of all participants. All measurements of the arch dimensions were made on the casts using an electronic digital sliding calliper. RESULTS: In the mandibular arch, when compared with the patients with thalassaemia, the unaffected control group subjects showed a (statistically) significantly larger incisor width, larger arch depth, and larger left and right anterior arch lengths (1.18, 2.58, and 1.85 and 1.12 mm, respectively). In the maxillary arch, there was a statistically significant difference in the mean incisor width (+/- 2.16 mm), arch depth (+/- 3.14 mm), inter-molar width (+/- 1.21 mm) and in the left anterior arch length (+/- 1.97 mm). The canine widths, premolar widths, left and right posterior arch length, and curve of Spee of both arches showed no statistically significant differences between the two groups. CONCLUSION: When compared to unaffected subjects, patients with beta-thalassaemia major exhibited: a narrower maxilla; a shorter maxilla and mandible; and smaller incisor widths for the maxillary and mandibular arches.     

Study of structural changes in canine maxillary trabecular bone after tooth extraction

All teeth on the right side of the upper and lower jaws were extracted from canine specimens; and changes in maxillary trabecular-bone structure caused by the resultant reduction in functional pressure were studied by means of image analysis of trabecular-bone density, width, specific length (which indicates bone length to unit area), and trabecular-bone orientations. Results 1. Trabecular-bone density Over the 13-month period, in comparison with the normal side, trabecular-bone density on the experimental side dropped to 69.4% in the incisor region, 82.2% in the premolar region, and from 60.0 to 68.0% in the molar region. The greatest reduction occurred in the molar region. 2. Trabecular-bone width Over the 13-month period, in comparison with the normal side, trabecular-bone width on the experimental side dropped to 86.9% in the incisor region, 86.1% in the premolar region, and from 66.4 to 71.4% in the molar region. The greatest reduction occurred in the molar region. 3. Specific length Over the 13-month period, in comparison with the normal side, specific length on the experimental side dropped to 81.9% in the incisor region, 82.9% in the premolar region, and from 65.6 to 70.5% in the molar region. The greatest reduction occurred in the molar region. 4. Orientation No regular trabecular-bone orientation was observed in the tooth-extraction sockets. In the incisor region, trabecular bone was often distributed at from 100 degrees to 120 degrees in relation to the dental roots. As time passed after extraction, the amount of bone with this orientation gradually decreased. At 13 months, amounts with bone orientation of from 40 degrees to 60 degrees had increased. In the premolar region, a great deal of trabecular bone was oriented at from 140 degrees to 150 degrees in relation to the dental roots. As time passed after extraction, the amount of bone with this orientation gradually decreased. At 13 months, amounts with bone orientation of from 110 degrees to 130 degrees had increased. In the molar buccal region, trabecular bone was often distributed at from 20 degrees to 40 degrees, and 90 degrees in relation to the dental roots. In the molar palatal region, trabecular bone was often distributed at from 120 degrees to 140 degrees in relation to the dental roots. At 13 months, the amount of trabecular bone oriented at about 90 degrees had increased.     

单侧上颌尖牙阻生对牙颌三维结构的影响

目的: 采用锥形束CT（CBCT）研究单侧尖牙阻生病例牙颌的三维结构特征,评估发生上颌尖牙阻生的相关风险因素,为正畸临床早期干预提供依据。方法: 选取30例单侧上颌尖牙阻生患者的CBCT,利用Romexis软件进行三维重建,测量、比较两侧牙颌三维结构特征指标,采用SPSS17.0软件包进行配对t检验和相关数据的回归分析。结果: 阻生侧尖牙和侧切牙倾斜度明显增大,尖牙牙冠更向近中、侧切牙向远中倾斜（P<0.001）;阻生侧尖牙体积更大、侧切牙体积更小（P<0.05）,当尖牙体积增大或侧切牙体积减小时,上颌尖牙的阻生概率增加;阻生侧牙弓弧形长度更短,牙弓宽度在尖牙区和前磨牙区更短（P<0.001）,而宽度在磨牙区无显著差异（P>0.05）,两侧牙弓长度在尖牙区、前磨牙区和磨牙区无显著差异（P>0.05）。结论: 上颌尖牙阻生伴随或导致同侧牙及牙槽骨三维方向发育异常,上颌尖牙阻生的严重程度与周围牙颌结构异常密切相关,提示上颌尖牙阻生可以早期预判、诊断,且可以实施有效的早期干预。     

上颌口腔腭侧黏膜疼痛敏感度的初步研究

目的:研究不同部位口腔上颌腭侧黏膜疼痛敏感度,发现相对敏感区域并提出相应对策,以减轻患者注射麻药时的疼痛感及全身并发证的发生。方法:对需拔除的上颌患牙进行局部浸润麻醉,采用碧兰麻及相对应的0.3mm×21mm细针头,注射部位距离腭侧牙龈缘约5mm,后记录注射部位的疼痛程度,所记录的疼痛程度是注射针刺入黏膜时的疼痛。疼痛分级采用国际通用方法,但加以改良,使之更详细。采用χ2检验分析各牙位的中重度和重度疼痛患者构成比。结果:800例患者中,无痛到中度疼痛患者646例,占总数的80.75%;中重度和重度疼痛患者154例,占19.25%。中重度和重度疼痛患者在中切牙组占47%,侧切牙组占39%,尖牙组占27%,第一前磨牙组占12%,第二前磨牙组占9%,第一磨牙和第二磨牙组均占8%,上颌结节区占4%。与前磨牙、磨牙和上颌结节区相比,中切牙、侧切牙和尖牙组的中重度和重度疼痛患者比例明显增加,差异有统计学意义(χ2检验,P<0.01)。结论:中切牙、侧切牙和尖牙腭侧黏膜疼痛敏感度较高,先表面麻醉后再注射麻药,以减少患者的疼痛感,同时减少患者的恐惧感和全身并发症的发生。     

Dental and alveolar arch widths in normal occlusion, class II division 1 and class II division 2

The aim of this study was to compare the transverse dimensions of the dental arches and alveolar arches in the canine, premolar, and molar regions of Class II division 1 and Class II division 2 malocclusion groups with normal occlusion subjects. This study was performed using measurements on dental casts of 150 normal occlusion (mean age: 21.6 +/- 2.6 years), 106 Class II division 1 (mean age: 17.2 +/- 2.4 years), and 108 Class II division 2 (mean age: 18.5 +/- 2.9 years) malocclusion subjects. Independent-samples t-test was applied for comparisons of the groups. These findings indicate that the maxillary interpremolar width, maxillary canine, premolar and molar alveolar widths, and mandibular premolar and molar alveolar widths were significantly narrower in subjects with Class II division 1 malocclusion than in the normal occlusion sample. The maxillary interpremolar width, canine and premolar alveolar widths, and all mandibular alveolar widths were significantly narrower in the Class II division 2 group than in the normal occlusion sample. The mandibular intercanine and interpremolar widths were narrower and the maxillary intermolar width measurement was larger in the Class II division 2 subjects when compared with the Class II division 1 subjects. Maxillary molar teeth in subjects with Class II division 1 malocclusions tend to incline to the buccal to compensate the insufficient alveolar base. For that reason, rapid maxillary expansion rather than slow expansion may be considered before or during the treatment of Class II division 1 patients.