A Study of the Morphology of Deciduous Mandibular Second Molars: 下顎第二乳臼齒之形態研究

Hung-Huey Tsai

Research output: Contribution to journalArticle

Abstract

Objectives. Variability in tooth morphology plays a significant role in the achievable results of restorative treatment. The purpose of this study was to identify variations in morphology of deciduous mandibular second molars and to compare their crown sizes and shapes in order to provide a detailed description of the morphological characteristics of these teeth.
Methods. The materials consisted of 142 (71 from boys and 71 from girls) dental stone casts of complete deciduous mandibular arches. Standardized photographs of the occlusal surfaces of the stone casts were obtained. The selected reference points on the photographs were digitized by an image analyzer, converted to an X-Y coordinate system, and input into a personal computer for data analysis. Eight linear and eight angular measurements were taken for each deciduous mandibular second molar. The deciduous mandibular second molars were classified as five-, six-, seven- and eight-cusp groups.
Results. Thirty-six percent of the deciduous mandibular second molars were comprised of five cusps, 52% were comprised of six cusps, 11% were comprised of seven cusps, and 1% was comprised of eight cusps. The eight-cusp group had three accessory cusps (ML, MR, and D). The six-cusp group was subdivided into 6ML, 6MB, and 6D types, while the seven-cusp group was subdivided into 7MLD and 7MLMB types according to the positions of the accessory cusp. Most teeth in the six-cusp group were of the 6ML type. Measurements of Ll, L2, L5, and A6 were significantly smalle; in the five-cusp group than in the 6ML type in boys; however, no significant difference was observed in girls.
Conclusions. The crown shape and size of deciduous mandibular second molars might be influenced by the existence of an accessory cusp in Taiwanese boys.
Original languageUndefined/Unknown
Pages (from-to)91-98
Number of pages8
JournalMid-Taiwan Journal of Medicine
Volume8
Issue number2
DOIs
Publication statusPublished - 2003

Keywords

  • crown shape
  • tooth morphology
  • cusp
  • crown size
  • mandibular deciduous second molar

Cite this

A Study of the Morphology of Deciduous Mandibular Second Molars : 下顎第二乳臼齒之形態研究. / Tsai, Hung-Huey.

In: Mid-Taiwan Journal of Medicine, Vol. 8, No. 2, 2003, p. 91-98.

Research output: Contribution to journalArticle

@article{4aee028e6ef3462b9bab39bf5f5c3df8,
title = "A Study of the Morphology of Deciduous Mandibular Second Molars: 下顎第二乳臼齒之形態研究",
abstract = "背景 牙體修復治療的成效受牙齒形態的變異性的影響。本研究的目的在於確認下顎第二乳臼齒的型態變異性並比較其牙冠大小與形狀的差異。方法 材料為142個(71個男童與71個女童)乳齒列牙弓石膏模型。取得石膏模型咬合面的照片後,將照片上的參考點用影像處理器數位化轉變成X-Y座標輸入電腦。在每個下頓第二乳臼齒測量了八個線及角度項目。結果 百分之三十六的下顎第二乳臼齒擁有多個咬頭,百分之五十二擁有6個,百分之十一擁有7個,百分之一擁有8個咬頭。八個咬頭群擁有3個副咬頭(ML、MB、及D)。依據副咬頭的位置6個咬頭群再區分成6ML、6MB、及6D型, 7個咬頭群則再區分成7MLD與7MLMB型。六個咬頭群裡大多數的牙齒屬於6ML型。男童5個H交頭群的測量項目Ll、L2、L多、及A6較6ML型明顯地小,但女童的多個咬頭群與6ML型之間並無統計上的差異。結論副咬頭的存在可能會影響台灣男童下顆第二乳臼齒的型態與大小。",
keywords = "crown shape, tooth morphology, cusp, crown size, mandibular deciduous second molar, 牙冠形狀, 牙齒形態, 牙冠大小, 咬頭, 下顎第二乳臼齒",
author = "Hung-Huey Tsai",
year = "2003",
doi = "10.6558/MTJM.2003.8",
language = "未定义",
volume = "8",
pages = "91--98",
journal = "Mid-Taiwan Journal of Medicine",
issn = "1029-3507",
publisher = "中臺灣醫學科學雜誌社",
number = "2",

}

TY - JOUR

T1 - A Study of the Morphology of Deciduous Mandibular Second Molars

T2 - 下顎第二乳臼齒之形態研究

AU - Tsai, Hung-Huey

PY - 2003

Y1 - 2003

N2 - 背景 牙體修復治療的成效受牙齒形態的變異性的影響。本研究的目的在於確認下顎第二乳臼齒的型態變異性並比較其牙冠大小與形狀的差異。方法 材料為142個(71個男童與71個女童)乳齒列牙弓石膏模型。取得石膏模型咬合面的照片後,將照片上的參考點用影像處理器數位化轉變成X-Y座標輸入電腦。在每個下頓第二乳臼齒測量了八個線及角度項目。結果 百分之三十六的下顎第二乳臼齒擁有多個咬頭,百分之五十二擁有6個,百分之十一擁有7個,百分之一擁有8個咬頭。八個咬頭群擁有3個副咬頭(ML、MB、及D)。依據副咬頭的位置6個咬頭群再區分成6ML、6MB、及6D型, 7個咬頭群則再區分成7MLD與7MLMB型。六個咬頭群裡大多數的牙齒屬於6ML型。男童5個H交頭群的測量項目Ll、L2、L多、及A6較6ML型明顯地小,但女童的多個咬頭群與6ML型之間並無統計上的差異。結論副咬頭的存在可能會影響台灣男童下顆第二乳臼齒的型態與大小。

AB - 背景 牙體修復治療的成效受牙齒形態的變異性的影響。本研究的目的在於確認下顎第二乳臼齒的型態變異性並比較其牙冠大小與形狀的差異。方法 材料為142個(71個男童與71個女童)乳齒列牙弓石膏模型。取得石膏模型咬合面的照片後,將照片上的參考點用影像處理器數位化轉變成X-Y座標輸入電腦。在每個下頓第二乳臼齒測量了八個線及角度項目。結果 百分之三十六的下顎第二乳臼齒擁有多個咬頭,百分之五十二擁有6個,百分之十一擁有7個,百分之一擁有8個咬頭。八個咬頭群擁有3個副咬頭(ML、MB、及D)。依據副咬頭的位置6個咬頭群再區分成6ML、6MB、及6D型, 7個咬頭群則再區分成7MLD與7MLMB型。六個咬頭群裡大多數的牙齒屬於6ML型。男童5個H交頭群的測量項目Ll、L2、L多、及A6較6ML型明顯地小,但女童的多個咬頭群與6ML型之間並無統計上的差異。結論副咬頭的存在可能會影響台灣男童下顆第二乳臼齒的型態與大小。

KW - crown shape

KW - tooth morphology

KW - cusp

KW - crown size

KW - mandibular deciduous second molar

KW - 牙冠形狀

KW - 牙齒形態

KW - 牙冠大小

KW - 咬頭

KW - 下顎第二乳臼齒

U2 - 10.6558/MTJM.2003.8

DO - 10.6558/MTJM.2003.8

M3 - 文章

VL - 8

SP - 91

EP - 98

JO - Mid-Taiwan Journal of Medicine

JF - Mid-Taiwan Journal of Medicine

SN - 1029-3507

IS - 2

ER -