MBT矫治前后牙弓宽度变化的模型分析研究

目的 分析牙列拥挤患者不拔牙与拔牙的MBT矫治对牙弓宽度变化的影响。方法 选择我院正畸科2008—2011年MBT矫治器治疗的牙列拥挤患者40例。其中轻中度牙列拥挤患者20例,使用MBT矫治器进行不拔牙正畸;中重度牙列拥挤患者20例,使用MBT矫治器进行拔除4颗第一前磨牙的拔牙正畸。测量术前术后石膏模型的牙弓宽度,对矫治前后不拔牙组和拔牙组的测量数据分别进行组内、组间统计学分析。结果 矫治前后不拔牙组:上颌尖牙间宽度增大,上下颌第一前磨牙、第一磨牙间宽度增大,有统计学意义;拔牙组:上颌尖牙间宽度增大,上下颌第二前磨牙、第一磨牙间宽度变小,有统计学意义。矫治前2组上下颌尖牙、第一磨牙间牙弓宽度相近,无统计学差异;矫治后不拔牙组上下颌第一磨牙间牙弓宽度大于拔牙组,有统计学意义,2组上下颌尖牙间牙弓宽度相近,差异无统计学意义。结论 不拔牙矫治牙弓宽度变化与拥挤部位、拥挤程度有关,拔牙矫治牙弓宽度变化主要与牙齿移动方向有关。拔牙矫治后尖牙间宽度不会减小。     

上颌埋伏阻生前牙正畸治疗的临床研究

目的：观察上颌埋伏阻生前牙应用固定正畸方法进行矫治的临床疗效,探讨埋伏阻生前牙有效的治疗方法。方法：对49例58颗上颌前牙埋伏阻生病例,应用固定正畸进行矫治,结合牙槽外科开窗术,对埋伏牙进行牵引。其中20颗进行开拓间隙使之自然萌出,38颗进行开窗封闭式牵引导萌矫治。结果：55颗阻生牙矫治后牙髓活力正常、未见埋伏牙及邻牙牙根吸收、牙周组织正常。开窗封闭式牵引导萌有3颗牙治疗失败,总体成功率94.8%。结论：应用固定正畸技术开拓间隙或结合牙槽外科开窗术导萌埋伏阻生牙,可有效保存上颌埋伏阻生前牙。     

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目的：探讨阻生上颌尖牙合适的临床处理策略,为其合理治疗提供依据。方法回顾2000-2012年期间在大连市口腔医院正畸科接受治疗的35例阻生上颌尖牙病例的临床资料,总结分析尖牙阻生状况及相应的治疗措施和疗效。临床处理方法包括拔除、助萌和导萌。结果拔除2例;只做正畸治疗的助萌法16例,留出足够间隙后等待阻生尖牙自行萌出,观察时间5～24个月,均取得良好治疗效果,矫治后阻生尖牙牙龈形态及牙根状况良好;正畸附加外科手术牵引的导萌法17例,除1例21岁男性患者外,其余16例均牵引到位,但矫治后部分阻生尖牙牙龈形态不如助萌法矫治后。结论当阻生上颌尖牙牙体严重畸形、根弯曲短小及高位近远中向横位阻生时考虑拔除;阻生上颌尖牙近远中向错位不严重,扩弓或减数拔牙即可为阻生尖牙留出足够萌出间隙,判断其能自然萌出时首选助萌法;阻生上颌尖牙近远中向错位严重或阻生尖牙已伤及邻牙牙根、仅用正畸治疗无法去除阻生尖牙萌出障碍时采用导萌法,导萌术后的牵引需注意控制牵引方向及大小,要避免伤及邻牙牙根,尽量使阻生牙从附着龈萌出,有利于形成良好的牙龈形态。     

成人骨性Ⅲ类错畸形伴腭侧水平阻生尖牙的正畸治疗

上颌尖牙是牙列中除第三磨牙外最易发生阻生的牙齿,对美观及咀嚼功能有重要作用。临床上对于垂直位或半垂直位阻生尖牙大多易于通过正畸牵引入牙弓,而水平阻生的尖牙矫治难度较大。该文报告1例通过外科开窗联合自制弹性牵引装置成功矫治成人上颌腭侧阻生尖牙,评价其治疗方法的可行性及疗效。     

不同部位拔牙对第三磨牙牙胚位置的影响

牙颌畸形的病因及临床症状复杂,要求正畸治疗方案具有多样性。随着基础研究的不断深入和临床技能的提高,正畸医师对拔牙部位有了更多的选择。国内外研究表明,拔牙矫治导致的磨牙近中移动及伴随的萌出间隙增加很可能降低第三磨牙的阻生。本文就目前国内外关于不同部位拔牙对第三磨牙牙胚位置的影响进行综述。     

一例间隙不足导萌病例的治疗取舍

<正>尖牙埋伏阻生在口腔正畸临床中较为常见,表现为尖牙萌出位置不足或完全不能萌出,易导致邻牙牙根吸收、牙源性感染、口角塌陷等^[1],对面部美观及口牙合功能影响较大,上颌尖牙是阻生牙中除智齿外发病率最高的阻生牙位,发病率约为1%～4%^[2]。其矫治难度较大,常需多学科协同治疗。现报道1例以非对称拔牙及导萌为主要治疗策略的牙列拥挤伴尖牙阻生的患者,旨在为此类病例的诊断与治疗提供参考。     

下颌第二磨牙阻生的病因及治疗方法

在正畸临床上,下颌第二磨牙的阻生虽然不如第三磨牙、上颌尖牙和下颌第二前磨牙的阻生来的常见,但是一旦发生,不但影响患者的咀嚼功能和牙弓的稳定性,还容易引起其近中邻牙的远中邻面龋,甚至牙髓根尖周病的发生。本文就近年来的一些相关文献报道进行归纳总结,就下颌第二磨牙阻生的病因和治疗方法作一综述。     

罕见上颌尖牙阻生致上颌前磨牙牙根重度弯曲根管治疗1例

埋伏阻生牙在临床上比较常见,易发部位为下颌第三磨牙和上颌尖牙[1].常常导致牙列不齐,咬合关系紊乱,邻牙牙根吸收以及牙弓长度减小等.阻生的牙囊还可能形成囊肿[2].阻生尖牙是临床上常见的一种牙齿畸形,埋伏阻生的原因较为复杂,临床表现各不相同.其中因尖牙阻生导致前磨牙发育异常的病例较少见.轻微阻生时牙齿可能萌出迟缓或错位...     

拔除第一前磨牙对第三磨牙倾角的影响

目的研究正畸治疗中拔除第一前磨牙进行矫治和非拔牙矫治对第二磨牙和第三磨牙倾角的影响。方法选择56例上下颌第三磨牙均存在的青少年正畸患者,按拔牙与否分为拔牙组（30例,拔除4颗第一前磨牙）和非拔牙组（26例）,通过术前术后曲面断层片来测量患者上下颌第三磨牙长轴和平面的交角,第二磨牙与平面的交角以及第二、第三磨牙长轴的交角,并进行统计学分析。结果拔牙与非拔牙组矫治前后第三磨牙倾角均有不同程度的改善。与非拔牙组相比,拔牙组上下颌第三磨牙长轴与平面交角的变化量更大,2组间年平均变化量的差异有统计学意义（P<0.05）;2组矫治前后上下颌第二、第三磨牙长轴交角的变化无统计学差异,但其年平均变化量在2组间则有统计学差异（P<0.05）。2组间上颌第二磨牙与平面交角的年平均变化量无统计学差异（P>0.05）,而下颌第二磨牙与平面交角的年平均变化量则有统计学差异（P<0.05）。结论拔除第一前磨牙进行正畸治疗有利于第三磨牙倾角的改善,对第三磨牙萌出有积极意义。     

6阻生与正畸治疗

６阻生与正畸治疗汕头市中心医院（５１５０３１）王友山，胡顺广，巫晓平阻生牙常发生在下颌第三磨牙、上颌第三磨牙及上颌尖牙。上颌第一磨牙发生阻生者极为罕见。作者遇到一例。患者，男，２５岁。口腔检查发现低位垂直阻生，牙冠萌出约１／２，牙冠外形同一致。均向倾...     

Shear bond strength differences of types of maxillary deciduous and permanent teeth used as anchor teeth

OBJECTIVE: To compare the bond strengths of identical orthodontic brackets bonded to maxillary deciduous and permanent teeth, which were used as anchor teeth in sectional edgewise appliance therapy, and to evaluate the modes of bracket/adhesive failure. MATERIALS AND METHODS: A total of 28 human maxillary teeth were divided into four groups by tooth type: permanent first premolars (group I), permanent second premolars (group II), deciduous canines (group III), and deciduous second molars (group IV). Each group consisted of seven teeth. Metal premolar brackets were bonded to these specimens using an acid-etching adhesive system. Shear bond strengths were measured using a universal testing machine, and the bracket/ adhesive failure modes were evaluated with the Adhesive Remnant Index. RESULTS: The shear strengths of the bonds on the deciduous canines and second molars were significantly lower than those on the permanent first and/or second premolars. There were no significant differences in shear bond strength between the permanent first and second premolars, and between the deciduous canines and second molars. The shear bond strengths of all four tooth types were higher than the clinically sufficient range of strengths from 6 to 8 MPa. Bond failure at the enamel-adhesive interface occurred more frequently in the deciduous second molars than in the permanent first premolars. CONCLUSIONS: There were significant differences in shear bond strength among different permanent and deciduous tooth types, but deciduous teeth could be used as anchor teeth in orthodontic treatment with sectional edgewise appliances.     

正畸治疗中磨牙的拔除和保留（四十八）——减数前磨牙与减数磨牙对相同错[牙合]矫治结果的影响

目的：探讨减数前磨牙与减数磨牙对相同错[牙合]矫治结果的影响。方法：选取2个同年龄,错[牙合]类型相近的病例,以典型病例形式分析减数前磨牙与减数磨牙设计模式对于矫治结果的区别和意义。结果：病例1采用减数第一前磨牙设计,最终只能保留24颗功能牙,第三磨牙阻生;病例2采用减数磨牙设计,最终保留28颗牙齿的牙列。结论：减数磨牙矫治适用于多数常规减数前磨牙病例,避免了减数前磨牙可能造成的第三磨牙阻生问题,同时又可以解决牙弓前、中、后段的问题。     

Delayed eruption of premolars with periodontitis of primary predecessors and a cystic lesion: a case report

Apical periodontitis after pulp therapy in a primary tooth can cause delayed eruption of the permanent successor. A case of bilateral delayed eruption of mandibular premolars is presented. The patient. a 13-year-old girl, was referred by her dentist. Oral findings showed that the right first and left second primary molars were retained. Other premolars had erupted. An orthopantomogram revealed apical periodontitis, affecting both retained primary molars. The right first mandibular premolar was impacted against the alveolar bone and root of the second premolar, and there was a large cystic lesion in close association with the left second mandibular premolar. Both primary molars were extracted, and the cystic lesion was treated by marsupialization. Fenestration and traction were performed on the right first premolar. Correct tooth alignment was achieved with orthodontic appliances. If the problem had been detected earlier, treatment of the premolars might have been easier. Clinical and radiological follow-up, therefore, of primary teeth that have undergone pulp therapy procedures should be performed until eruption of succedaneous teeth.     

Total impaction of deciduous maxillary molars: two case reports

AIM: The purpose of this report is to present two cases of totally impacted maxillary deciduous molars, considered a rarity in dental practice. BACKGROUND: Primary tooth impaction is quite rare during the development of primary dentition. Various factors contribute to the impaction of a deciduous tooth, including anklyosis, congenitally missing permanent teeth, defects in the periodontal membrane, trauma, injury of the periodontal ligament, precocious eruption of the first permanent molar, defective eruptive force, or a combination of these factors. REPORTS: Case #1: An 18-year-old male presented with a complaint of spontaneous repetitious pain in the maxillary right premolar region. The maxillary right second premolar was clinically absent. Panoramic and periapical radiographs revealed an impacted second premolar close to the inferior wall of the maxillary sinus and an impacted deciduous molar deeply embedded in bone within the maxillary sinus. Case #2: A 14-year-old girl presented with a complaint of crowding of the maxillary teeth. The maxillary right second premolar and the maxillary permanent canines were clinically absent. A panoramic radiograph revealed an impacted maxillary right second premolar and an impacted deciduous molar embedded within bone close to the inferior wall of the maxillary sinus. SUMMARY: The total impactation of deciduous teeth is a rare condition, and few cases have been reported in the literature. The condition generally affects the mandibular second deciduous molar and the maxillary first deciduous least often. In this paper, two cases of totally impacted maxillary deciduous molars are reported.     

基于锥形束CT的多生牙新分类方法临床意义研究

目的　应用锥形束CT（cone-beam CT,CBCT）对多生牙进行新的临床分类,并分析新分类方法的临床意义。方法　收集2016—2019年首都医科大学附属北京友谊医院口腔科的CBCT影像资料5100例,其中多生牙患者209例,共计多生牙278颗。应用CBCT对多生牙进行新的临床分类,包括萌出型、骨埋伏高位型、骨埋伏低位型、骨埋伏复杂型和牙弓外型,并分析其临床意义。结果　（1）临床资料分析：多生牙发生率为4.1%,其中有1颗多生牙的患者占76.6%,有2颗多生牙的患者占19.1%,有3颗及以上多生牙的患者占4.3%。多生牙好发部位依次为：上颌切牙区、上颌磨牙区、下颌尖牙及前磨牙区、上颌尖牙及前磨牙区、下颌磨牙区。34.9%的多生牙对邻近恒牙产生了继发影响,以萌出错位及阻生为主,主要发生在上颌切牙区。（2）新分类方法的临床意义分析：上颌切牙区多生牙以骨埋伏低位型及萌出型为主,尖牙、前磨牙及磨牙区多生牙以萌出型为主。不同类型多生牙对邻近恒牙产生继发影响的发生率不同或不全相同（χ2 = 26.057,P < 0.001）,提示对邻近恒牙易产生继发影响的多生牙类型依次为：萌出型、骨埋伏复杂型、骨埋伏高位型、牙弓外型、骨埋伏低位型。结论　基于CBCT的多生牙新分类方法简单实用,其中萌出型、骨埋伏复杂型及骨埋伏高位型多生牙更易产生错牙合畸形,建议尽早拔除多生牙、定期随访,必要时正畸治疗。     

基于锥形束CT的多生牙新分类方法临床意义研究

 目的　应用锥形束CT（cone-beam CT，CBCT）对多生牙进行新的临床分类，并分析新分类方法的临床意义。方法　收集2016-2019年首都医科大学附属北京友谊医院口腔科的CBCT影像资料5100例，其中多生牙患者209例，共计多生牙278颗。应用CBCT对多生牙进行新的临床分类，包括萌出型、骨埋伏高位型、骨埋伏低位型、骨埋伏复杂型和牙弓外型，并分析其临床意义。结果　（1）临床资料分析：多生牙发生率为4.1%，其中有1颗多生牙的患者占76.6%，有2颗多生牙的患者占19.1%，有3颗及以上多生牙的患者占4.3%。多生牙好发部位依次为：上颌切牙区、上颌磨牙区、下颌尖牙及前磨牙区、上颌尖牙及前磨牙区、下颌磨牙区。34.9%的多生牙对邻近恒牙产生了继发影响，以萌出错位及阻生为主，主要发生在上颌切牙区。（2）新分类方法的临床意义分析：上颌切牙区多生牙以骨埋伏低位型及萌出型为主，尖牙、前磨牙及磨牙区多生牙以萌出型为主。不同类型多生牙对邻近恒牙产生继发影响的发生率不同或不全相同（χ2 = 26.057，P < 0.001），提示对邻近恒牙易产生继发影响的多生牙类型依次为：萌出型、骨埋伏复杂型、骨埋伏高位型、牙弓外型、骨埋伏低位型。结论　基于CBCT的多生牙新分类方法简单实用，其中萌出型、骨埋伏复杂型及骨埋伏高位型多生牙更易产生错牙合畸形，建议尽早拔除多生牙、定期随访，必要时正畸治疗。     

Orthodontic bands and directly bonded brackets: a review of clinical failure rate

The two main techniques available for the fixed attachment of orthodontic appliances to teeth are orthodontic bands and directly bonded brackets. The data available shows little difference in the overall failure rates recorded for orthodontic bands (4–21 per cent) and directly bonded brackets (4–30 per cent).The failure rate for bands and directly bonded brackets on individual teeth indicates that for molar and premolar teeth the failure rates were lowest when using conventional bands as opposed to directly bonded brackets, while for canine and incisor teeth the failure rates were lowest when using directly bonded brackets rather than conventional bands.From the published data presented in this paper it is concluded that the lowest failure rates both overall and for individual teeth could be achieved by selectively combining the use of conventional bands on premolars and molars and directly bonded brackets on canines and incisors.     

Effect of premolar extraction on mandibular third molar impaction in young adults

Objective:To test the null hypothesis that orthodontic therapy with or without premolar extraction does not result in any difference in third molar impaction.Materials and Methods:Two groups were formed: 22 patients in one group with first premolar extractions and 22 patients in the other group without extractions. All patients were nongrowing subjects who had normal gonial angles and were skeletal Class I at the beginning of treatment. The available space for third molars, inclination of second and third molars, and angle between the second and third molars were evaluated. Also, the correlation of measured parameters and type of orthodontic therapy with the eruption of third molars was evaluated.Results:Of the third molars, 81.8% were impacted in the nonextraction group and 63.6% were impacted in the extraction group. Impaction of mandibular third molars was significantly correlated to the pretreatment and posttreatment inclination of third molars and the angle between the second and third molars. In the extraction therapy group, the retromolar distance increased significantly with a mean of 1.30 ± 1.25 mm.Conclusions:When the inclination of the third molar is inconvenient, the tooth may remain impacted even if there is enough retromolar space.     

Is orthodontic treatment without premolar extractions always non‐extraction treatment?

While it is common in contemporary orthodontic and orthopaedic treatment to commence treatment for many growing patients during the mixed-dentition, the creation of anterior space, often involving the attempted distalization or holding-back of the upper and lower permanent molar teeth has been shown to commonly result in posterior space deficiencies. Although the extractions of permanent premolar teeth may have been avoided, the developing second and third permanent molars are often affected, so that third molar impaction results in many cases. This is not to say that orthodontic treatment carried-out without premolar extractions is not ideal in many cases, but on the available evidence, so-called absolute 'non-extraction' protocols should be questioned, so that both the dental profession and the public at large are not misled.     

Influence of third molar space on angulation and dental arch crowding

The influence of the third molars on mandibular incisor crowding has been extensively studied but remains controversial. The purpose of this study was to ascertain whether, in Mongolian subjects, the lower third molar can affect anterior crowding and/or the inclination of teeth in the lower lateral segments. Panoramic radiographs, 45° oblique cephalograms, and dental casts were taken from Mongolian subjects (age range 18.3–24.1 years, mean 21.0 years) exhibiting impaction of all four third molars and an Angle Class I molar relationship. The Ganss ratio was calculated using panoramic radiographs, whereas the gonial angle and angulation of lower canines, premolars and molars were measured using 45° oblique cephalograms. Little’s index of irregularity was calculated using dental casts. Significant relationships between the angulation of the third and second molars and between the first molars and second premolars were found. Conversely, there was no significant correlation between the angulation of third molars, first premolars and canines. The Ganss ratio calculations showed that the lower first and second molars and the second premolars inclined mesially if there was insufficient space for the lower third molars. However, there was no significant correlation between Little’s index of irregularity and third molar angulation. Furthermore, although the third molar influences the lateral segments, no obvious relationship between the third molar and anterior crowding was observed. Therefore, the angulation of the third molar appears not to cause anterior crowding.