Saravanakumar Prathibha, Thirumalai Thangarajan Saravanan, Mani Umamaheswari, Kumar V Anand
Department of Prosthodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai, India.
Cureus. 2017 Apr 24;9(4):e1189. doi: 10.7759/cureus.1189.
Resorption of mandibular ridges is a multifactorial and biomechanical disease that is chronic, progressive, irreversible, and cumulative leading to loss of sulcular depth, vertical dimension loss, and decreased lower facial height. Some common neurological, hormonal, and metabolic disorders affect the adaptability of dentures, and this can be diagnosed by a trained prosthodontist with proper history-taking and clinical examination.The denture becomes passive due to complex neuromuscular control and causes difficulties in impression-making, mastication, and swallowing, which in turn leads to loss of retention and stability in complete dentures. Hence, residual ridge resorption becomes a challenging scenario for a clinician during fabrication of complete dentures. The neutral zone concept plays a significant role in overcoming these challenges. The neutral zone is the area where the outward forces from the tongue are neutralized or nullified by the forces of the lips and cheeks acting inward during functional movements.The neutral zone technique is an alternative approach for the construction of lower complete dentures. It is most effective for dentures where there is a highly atrophic ridge and history of denture instability. The technique aims to construct a denture that is shaped by muscle function and is in harmony with the surrounding oral structures. The technique is by no means new, but it is a valuable one. It is rarely used because of the extra clinical step involved and its complexity. Complete and partial denture failures are often related to non-compliance with neutral zone factors. Thus, the evaluation of the neutral zone is an important factor. Increased retention and stability with reduced chairside time are the salient features of this new approach to any clinically challenging situation in complete dentures.This clinical report describes a modification of the conventional neutral zone technique using improvised procedures to minimize chairside visits for a patient with an atrophic mandibular ridge and neuromuscular incoordination.
下颌牙槽嵴吸收是一种多因素的生物力学疾病，具有慢性、进行性、不可逆和累积性的特点，会导致龈沟深度丧失、垂直距离降低以及面下高度减小。一些常见的神经、激素和代谢紊乱会影响义齿的适应性，经过培训的口腔修复医生通过适当的病史采集和临床检查可以对此进行诊断。由于复杂的神经肌肉控制，义齿会变得被动，从而导致印模制取、咀嚼和吞咽困难，进而导致全口义齿固位和稳定性丧失。因此，在全口义齿制作过程中，剩余牙槽嵴吸收对临床医生来说是一个具有挑战性的情况。中性区概念在克服这些挑战方面发挥着重要作用。中性区是在功能运动过程中，来自舌头的向外力量被向内作用的嘴唇和脸颊的力量抵消或消除的区域。中性区技术是一种用于制作下颌全口义齿的替代方法。对于牙槽嵴高度萎缩且有义齿不稳定病史的义齿，该技术最为有效。该技术旨在构建一个由肌肉功能塑造且与周围口腔结构协调一致的义齿。该技术绝非新技术，但却是一项有价值的技术。由于涉及额外的临床步骤及其复杂性，它很少被使用。全口和局部义齿失败通常与未遵循中性区因素有关。因此，中性区的评估是一个重要因素。在全口义齿任何具有临床挑战性的情况下，增加固位和稳定性并减少临床操作时间是这种新方法的显著特点。本临床报告描述了对传统中性区技术的一种改进，采用了简易程序，以尽量减少患有萎缩性下颌牙槽嵴和神经肌肉不协调患者的临床就诊次数。
