BIOCHEMICAL INFLUENCES ON CONDYLAR CARTILAGE GROWTH

众所周知，髁状突的生长速度 下颌骨的软骨可以响应于 它的生物力学环境 但令人惊讶的是， 调节这种反应的因素或其范围内的限制 这些因素是有效的。 虽然大多数调查 都集中在下颚突出的假设影响上 最近的研究表明，一个关键因素 很可能是在模式或强度的变化 由突起产生的压缩载荷。 可是 很少有经验数据是关于反应的 髁突软骨压缩关节力，特别是与 考虑到间歇性的力量被传递到 软骨在咀嚼和切割。 最好的- 已经在体外进行了这个问题的对照研究， 但这些发现对活体动物需求的适用性 进行评估。 拟议的研究将调查 髁突软骨对间歇性压力的反应 体内的力量 具体的装载方式将被强加于 慢性刺激下颌升降肌组织 使用细金属丝留置电极，从而允许 接头荷载的大小、频率和模式可变化 为了比较的目的。 髁突软骨信息 还将寻求对一系列载荷幅值的响应 至于完全消除关节力（由 磨牙咬合夹板）。 此外，可能的影响， 频率和加载模式仍然几乎 一个完全未被探索但具有潜在意义的研究领域 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 髁状突软骨将使用生物化学（（3 H）- 胸苷、（35 S）-硫酸盐掺入和（45 Ca）-摄取）， 组织化学和放射自显影技术。 数据 这将加深我们对人类能力的理解。 髁突软骨，也许还有其他次级软骨， 对生物物理刺激的反应。 更详细地了解 这种组织的适应性限制，特别是对于那些 最大程度或持续时间所需的刺激类型 的反应，应该是明显的好处，为治疗 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.