微种植体支抗改善露龈微笑的效果

目的：观察微种植体支抗即刻负载矫治露龈微笑的临床效果。方法：选择露龈微笑拔牙患者10例,在其上颌唇侧侧切牙与尖牙根尖牙槽骨处植入微螺钉种植体,即刻用螺旋弹簧将微螺钉和上颌中切牙及侧切牙连在一起,每侧施力0.735 N,4周复诊1次。通过X线头影测量、模型分析及临床观察,比较矫治前后与露龈微笑有关的参数变化情况。结果：露...     

Influence of bimaxillary protrusion on the perception of smile esthetics

Objectives:

To evaluate the impact of bimaxillary protrusion on smile esthetics as perceived by dental professionals and laypersons.

Methods:

One hundred and fifty evaluators, equally distributed into their respective panels (orthodontists, general dentists, and laypersons), participated in this cross-sectional study conducted in April to December 2012 in Riyadh, Saudi Arabia. The patient sample consisted of 14 female patients divided equally into 2 groups: bimaxillary protrusion patients, and patients who have had 4-premolar extraction treatment. Two standardized photographs (frontal and three-quarter close-up smile views), and a lateral cephalogram were taken for each patient. The evaluators were asked to rate the attractiveness of each photo according to a 100-mm visual analog scale. These esthetic ratings were correlated with the patients’ cephalometric measurements.

Results:

The bimaxillary protrusion group was rated significantly as less attractive than the treatment group by each evaluator panel. Panel comparison showed that laypeople were less receptive of bimaxillary protrusion than dental professionals. Frontal and three-quarter views of the same smiles were not similarly rated for esthetic perceptions. Correlational analysis revealed that the dentoalveolar measurement with the highest significant negative correlation to the smile esthetics was the upper incisors to palatal plane (U1-PP) angle.

Conclusion:

Patients with bimaxillary protrusion were found to be less attractive than patients who were treated for the condition. This was especially evident among the laypersons. An increase in the upper incisor inclination, as well as a decrease in the interincisal angle compounds the bimaxillary effect.Bimaxillary protrusion is a condition characterized by protrusive and proclined upper and lower incisors and an increased prominence of the lips.1 It is seen commonly in African-American and Asian populations, but it can be seen in almost every ethnic group.1 Many patients with bimaxillary protrusion seek orthodontic care to decrease this procumbency. The goals of orthodontic treatment of this condition include the retraction of maxillary and mandibular incisors with a resultant decrease in soft tissue procumbency and convexity.1 This is most commonly achieved by the extraction of the 4 first premolars.1-4 In a study by Farrow et al,2 the African Americans preferred a straighter profile than what has been measured as normal for their race. Dawjee et al5 found that most African subjects with bimaxillary protrusion would want an extraction orthodontic treatment to change their facial profile to the ideal. More recently, Marques et al4 assessed the esthetic perceptions of the results of orthodontic treatment that alters the profile of black patients with bimaxillary protrusion through the extraction of 4 premolars. Their findings supported the view that the society perceives straight profiles as esthetically more pleasing in comparison with protruding profiles. All previously published studies have reported the perceived esthetics of bimaxillary protrusion based on profile views. The problem with this is that people do seldom see their own profiles. They evaluate their facial smile, or dental esthetics from a frontal view, and therefore, the usefulness of this approach is questionable.6 DeLoach7 supported this notion when he found that participants could not recognize their own profile type, and they had never given any thought to the nature of their own facial profile. He suggested that the laypersons’ esthetic preferences may be based primarily on facial features other than the profile.7 Esthetic perception varies from person to person and is influenced by their personal experience and social environment.6 For this reason, professional opinions regarding the evaluation of esthetics may not coincide with the perceptions and demands of patients or laypeople. Several studies revealed that dentists, particularly orthodontists, are less tolerant than the general public to some dentofacial attributes.8-12 As a result, some dentists and orthodontists might overestimate the need for orthodontic treatment.11 On the other hand, some studies indicated that lay individuals are less tolerant than the dental clinicians.13-16 This kind of disagreement might lead to the misunderstanding of the orthodontic patients’ demands. Despite these important issues, there is a paucity of information in the literature in terms of the perceived impact of bimaxillary protrusion on smile esthetics. The main aims of the present study were to evaluate the esthetic impact of bimaxillary protrusion in different close-up smile views as perceived by orthodontists, general dentists, and laypersons, and correlate their perceptions with specific cephalometric measurements.     

佛教何以在印度消失

印度佛教曾对印度的生活和文化有过深远而正面的影响,但印度佛教却逐渐衰落和最终消失。究其根源是佛教取代不了印度的传统的根底——种姓制度。种姓制度虽然严酷,但是对经常处在动乱和纷争之中的印度次大陆的百姓,最起码给了人的身份的认同和归属感,这也意味着人生的安顿。何况印度教比起婆罗门教而言,它既提出了种种维护种姓差别的办法,也设计了使这种差别免遭破坏的防御和修复机制。佛教最终淹没在印度教的洪流之中。