@多生牙mesiodens(正中贅生牙)的臨床處理－崇愛牙醫診所(資料重建中,歡迎新舊朋友)

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mesiodens在英文的字典裡解釋為:

A supernumerary tooth located in the midline of the anterior maxillae between the maxillary central incisor teeth(位於上顎兩中切牙的中間的多生牙)

Mesiodentes are the most common supernumerary teeth, occurring in 0.15% to 1.9% of the population(非常常見的多生牙,在人口數的佔率為0.15~1.9%)

The cause of mesiodentes is not fully understood, although proliferation of the dental lamina and genetic factors have been implicated. Mesiodentes can cause delayed or ectopic eruption of the permanent incisors, which can further alter occlusion and appearance. It is therefore important for the clinician to diagnose a mesiodens early in development to allow for optimal yet minimal treatment.

(發生的原因並未全然知道,雖然牙板的增殖和基因的因素被證實是有關連的,mesiodens會導致永久門牙的延遲或是異位萌出,會更進一步影響咬合與外觀的,因此,臨床醫生必須儘早在牙齒發育過程中注意診斷與更進一步給予適當的治療)

Treatment options may include surgical extraction of the mesiodens. If the permanent teeth do not erupt in a reasonable period after the extraction, surgical exposure and orthodontic treatment may be required to ensure eruption and proper alignment of the teeth. In some instances, fixed orthodontic therapy is also required to create sufficient arch space before eruption and alignment of the incisor(s). Early diagnosis allows the most appropriate treatment, often reducing the extent of surgery, orthodontic treatment and possible complications. This paper outlines the causes and modes of presentation of mesiodentes, and presents guidelines for diagnosis and management of nonsyndromic mesiodentes.

(臨床上不外乎運用外科手術與矯正的方法來改正咬合)

在早期混合齒列，屬於恆齒列的正中贅生芽常因干擾恆門牙發育，才被發現，可是早在乳齒列時，就可由X─光片發現，在乳齒列可預估其萌出與否，或是否會造成併發症，以確認未萌出正中贅生牙拔除時機，期望能減少正中贅生牙造成的併發症。

(1)正中贅生牙牙根發育速度在以與恆門牙相等者居多，順生且接近恆門牙切緣者，常造成乳門牙提早脫落，而先恆門牙萌出。

(2)位在恆門牙牙根之上方的正中贅生牙不會干擾恆門牙咬合發育，所以只要定期檢查即可。

(3)除上述情形之外的正中贅生牙拔除時機，須等恆門牙牙根發育達諾拉式分類法(nolla stage)第8階段以上。

~~Nolla's stage

(4)正中贅生牙造成的併發症等其拔除後再予矯正，仍可得滿意結果。

(from:http://www.ceps.com.tw/ec/ecjnlarticleView.aspx?jnliid=453&issueiid=3974&atliid=36781)

正中贅生齒中，以腭側(98.1%)、錐形(82.25%)、反向萌發(57.67%)的比例較多。有半數以上病患的門齒萌發會受影響，其影響包括阻礙門齒萌發、門齒異位萌發以及造成過大的齒縫間隙。當病患有不正常的正中門齒萌發現象時，應接受上顎前牙區放射線攝影檢查，來確認是否起因自贅生齒。(from:http://www.taiwanclassic.com/teps/ec_en/ecjnlarticleView.aspx?jnlcattype=1&jnlptype=5&jnltype=44&jnliid=475&issueiid=59747&atliid=1017778)

正中贅齒常在乳牙齒列和早期混合齒列造成正中齒間缝、萌牙異常以及咬合不正，甚至引起骨頭破壞、牙根吸收、齒髓壞死或形成囊腫

(from:http://www.ceps.com.tw/ec/ecjnlarticleView.aspx?atliid=84106&issueiid=7427&jnliid=475)

Mesiodens is a midline supernumerary tooth commonly seen in the maxillary arch. It is the most significant dental anomaly affecting permanent dentition mainly and primary dentition rarely. It may occur as an isolated dental anomalous condition or may be associated with a syndrome. Many theories have been promulgated to explain its etiology. But an exact etiology is still obscure. Incidence of mesiodens in children varies from 0.15 to 3.8%. Boys are affected more (2 : 1) than Girls. Morphologically, mesiodens may be of three types: the most commonly seen is conical, while tuberculate and supplementary types.

(from: http://www.ncbi.nlm.nih.gov/pubmed/16224138)

Results showed that males were affected four times as frequently as female. Thirty-five percent of the patients had more than one supernumerary tooth. About 67% of the mesiodens were conical in shape and about 34% of the mesiodens were in the upward position. The age and sex distribution, number of mesiodens per patient, shape, direction, size, and effect on permanent upper incisors are also presented in this study.(from: http://www.koreamed.org/SearchBasic.php?RID=197405&DT=1

)

寬大的上頜中切牙間隙( 4 m m以上)絕大多數由正中多生牙引起,早期摘除有礙的正中多生牙對兒童中切牙間隙過大的自行調整有重要意義.(from: http://scholar.ilib.cn/Abstract.aspx?A=hxkqyxzz200202014)

Supernumerary teeth, which is described as teeth or tooth substance that develops in excess of deciduous and permanent teeth, most commonly involve the anterior maxilla. Mesiodens are one type of supernumerary teeth that develops in paramedian space of premaxilla. Sometimes mesiodens can be inverted with its crown facing the nasal cavity. Because of its own pathology and possible disruption of neighboring normal teeth, supernumerary teeth should be removed regardless of its eruption. We experienced two cases of mesiodens detected in the nasal floor and so report these cases with a review of literature. (http://www.koreamed.org/SearchBasic.php?RID=389933&DT=1&QY=%22Korean+J+Otolaryngol+-+Head+Neck+Surg%22+%5BJTI%5D++AND+2007+%5BDPY%5D)發生在nasal cavity的mesiodens

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