BIOCHEMICAL INFLUENCES ON CONDYLAR CARTILAGE GROWTH

已经很好地确定了髁状突的生长速度 下颌骨的软骨可以根据以下变化而改变 它的生物力学环境。然而，令人惊讶的是，人们对此知之甚少 调节这种反应的因素或内在的限度 其中这些因素是有效的。尽管大多数调查 都集中在下颌突出可能产生的影响上 肌肉学，最近的研究表明，一个关键因素 很可能是模式或强度的变化 由突起产生的压缩载荷。然而，非常 几乎没有什么经验数据可以用来说明 髁突软骨对压缩关节的作用力，特别是在 关于传递给 咀嚼和切开过程中的软骨。最好的- 关于这个问题的对照研究已经在体外进行了， 但这些发现对活体动物需求的适用性 接受评估。拟议的研究将调查 髁突软骨对间歇性压迫的反应 体内的力量。具体的加载方式将被强加于 慢性刺激颌骨提升肌形成软骨 使用细丝留置电极，从而允许 关节载荷的大小、频率和模式将发生变化 以作比较。关于髁状突软骨的信息 还将寻求对一定范围的加载幅度的响应 关于完全消除关节力(由 磨牙咬合夹板)。此外， 频率和负荷模式几乎保持在 完全未经探索，但可能具有重大意义的调查领域 使用这种方法进行检查。有丝分裂活动率， 基质合成和矿化/骨形成 将使用生化((~3H)-)来评估髁突软骨。 胸腺嘧啶核苷，(35S)-硫酸盐掺入和(45Ca)-摄取)， 组织化学和放射自显影技术。数据 所取得的成果应该会加深我们对 髁突软骨，也许还有其他次级软骨，以 对生物物理刺激做出反应。更详细地了解 这种组织的适应极限，尤其是对于那些 使幅度或持续时间最大化所需的刺激类型 的反应，应该有明显的治疗效果 目的。

It has been well established that the growth rate of the condylar cartilage of the mandible can be altered in response to changes in its biomechanical environment. Yet surprisingly little is known of the factors which regulate this response or of the limits within which these factors are effective. Although most investigations have focussed on the presumed influence of the protrusive jaw musculature, recent studies have suggested that a critical factor may well be the alteration in the pattern or intensity of compressive loading produced by the protrusion. However, very few empirical data are available concerning the response of the condylar cartilage to compressive articular forces, especially with regard to the intermittent forces that are transmitted to the cartilage during mastication and incision. The most well- controlled studies of this question have been conducted in vitro, but the applicability of these findings to the living animal needs to be evaluated. The proposed research will investigate the response of the condylar cartilage to intermittent compressive forces in vivo. Specific loading modalities will be imposed on the cartilage by chronic stimulation of the jaw elevator musculature using fine wire indwelling electrodes, thereby permitting the magnitude, frequency, and pattern of joint loading to be varied for comparative purposes. Information on condylar cartilage response to a range of loading amplitudes will be sought, as well as to the complete removal of articular forces (effected by a molar bite splint). In addition, the possible influence of the frequency and the pattern of loading remains an almost completely unexplored, but potentially significant, area of inquiry to be examined using this methodology. Rate of mitotic activity, matrix synthesis, and mineralization/bone formation in the condylar cartilage will be evaluated using biochemical ((3H)- thymidine, (35S)-sulfate incorporation and (45Ca)-uptake), histochemical, and radioautographic techniques. The data obtained should deepen our understanding of the capability of the condylar cartilage, and perhaps other secondary cartilages, to respond to biophysical stimuli. A more detailed appreciation of the adaptive limits of this tissue, especially with regard to those types of stimuli required to maximize the magnitude or duration of the response, should be of obvious benefit for therapeutic purposes.