Chu Stephen J, Tan Jocelyn H-P, Stappert Christian F J, Tarnow Dennis P
Department of Periodontology and Implant Dentistry, College of Dentistry, New York University, New York, NY, USA.
J Esthet Restor Dent. 2009;21(2):113-20. doi: 10.1111/j.1708-8240.2009.00242.x.
The location of the gingival zenith in a medial-lateral position relative to the vertical tooth axis of the maxillary anterior teeth remains to be clearly defined. In addition, the apex of the free gingival margin of the lateral incisor teeth relative to the gingival zeniths of the adjacent proximal teeth remains undetermined. Therefore, this investigation evaluated two clinical parameters: (1) the gingival zenith position (GZP) from the vertical bisected midline (VBM) along the long axis of each individual maxillary anterior tooth; and (2) the gingival zenith level (GZL) of the lateral incisors in an apical-coronal direction relative to the gingival line joining the tangents of the GZP of the adjacent central incisor and canine teeth under healthy conditions.
A total of 240 sites in 20 healthy patients (13 females, 7 males) with an average age of 27.7 years were evaluated. The inclusion patient criteria were absence of periodontal disease, gingival recession, or gingival hypertrophy as well as teeth without loss of interdental papillae, spacing, crowding, existing restorations, and incisal attrition. GZP dimensions were measured with calibrated digital calipers for each individual tooth and within each tooth group in a medial-lateral direction from the VBM. GZLs were measured in an apical-coronal direction from a tangent line drawn on the diagnostic casts from the GZPs of the adjacent teeth.
This study demonstrated that all central incisors displayed a distal GZP from the VBM, with a mean average of 1 mm. Lateral incisors showed a deviation of the gingival zenith by a mean of 0.4 mm. In 97.5% of the canine population, the GZP was centralized along the long axis of the canine. The mean distance of the contour of the gingival margin in an apical-coronal direction of the lateral incisors (GZL) relative to gingival line joining the tangent of the adjacent central and canine GZPs was approximately 1 mm.
This investigation revealed a GZP mean value of 1 mm distal from the VBM for the central incisor tooth group. The lateral incisors showed a mean average of 0.4 mm. The canine tooth group demonstrated almost no deviations of the GZP from the VBM. The GZL of the lateral incisors relative to the adjacent central incisor and canine teeth were more coronal by approximately 1 mm. These data could be used as reference points during esthetic anterior oral rehabilitation.
The information presented in this article can be clinically applied to reestablish the proper intratooth GZPs of the maxillary anterior teeth during periodontal crown lengthening or root coverage procedures. In addition, the intra-arch gingival level of the lateral incisor gingival zenith relative to the adjacent central and canine teeth can be appropriately established.
上颌前牙牙龈顶点相对于垂直牙轴在内侧 - 外侧位置的定位仍有待明确界定。此外，侧切牙游离龈缘顶点相对于相邻近中牙牙龈顶点的位置尚未确定。因此，本研究评估了两个临床参数：（1）沿每颗上颌前牙长轴从垂直平分中线（VBM）测量的牙龈顶点位置（GZP）；（2）在健康状况下，侧切牙牙龈顶点相对于连接相邻中切牙和尖牙GZP切线的牙龈线在根尖 - 冠方方向的牙龈顶点水平（GZL）。
对20名平均年龄27.7岁的健康患者（13名女性，7名男性）的总共240个部位进行评估。纳入患者的标准为无牙周病、牙龈退缩或牙龈肥大，以及牙齿无牙间乳头丧失、间隙、拥挤、现有修复体和切缘磨损。使用校准的数字卡尺在每个牙齿的内侧 - 外侧方向从VBM测量每颗牙齿以及每个牙组内的GZP尺寸。GZL从相邻牙齿GZP在诊断模型上绘制的切线沿根尖 - 冠方方向测量。
本研究表明，所有中切牙的GZP均位于VBM的远中，平均为1mm。侧切牙牙龈顶点平均偏差为0.4mm。在97.5%的尖牙群体中，GZP沿尖牙长轴居中。侧切牙牙龈缘轮廓在根尖 - 冠方方向（GZL）相对于连接相邻中切牙和尖牙GZP切线的牙龈线的平均距离约为1mm。
本研究揭示中切牙牙组的GZP平均位于VBM远中1mm处。侧切牙平均为0.4mm。尖牙牙组的GZP几乎没有偏离VBM。侧切牙相对于相邻中切牙和尖牙的GZL在冠方约高1mm。这些数据可作为口腔前部美学修复时的参考点。
本文提供的信息可在临床应用于牙周冠延长或根覆盖手术过程中重新建立上颌前牙正确的牙内GZP。此外，可适当确定侧切牙牙龈顶点相对于相邻中切牙和尖牙的牙弓内牙龈水平。
