Denes Balazs J, Lazzarotto Benjamin, Bresin Andrea, Kiliaridis Stavros
Department of Orthodontics, Clinique Universitaire de Médecine Dentaire, Faculty of Medecine, University de Geneva, Switzerland.
Specialist clinic of Orthodontics, University Clinics, Public dental service Region Västra Götaland, Göteborg, Sweden.
Eur J Orthod. 2018 May 25;40(3):312-316. doi: 10.1093/ejo/cjx072.
Apart from the primary effect of bite-blocks on tooth position, they may also influence the mandibular condylar growth. Our aim was to investigate their influence on the condylar morphology, with variable masticatory forces.
Fifty-two 4-week old male rats were divided into hard and soft diet groups in order to create individuals with different masticatory muscle capacity. Two weeks later, they were equally divided into bite-block and control groups. After a total of 6 weeks experimental time, the animals were sacrificed. The mandibles were scanned with high-resolution micro-CT and 3D analysis was performed on the condylar neck and head of the condyle. The volume and the length of the condylar process were measured. Statistical analysis was done with a one-way analysis of variance.
The use of bite-blocks decreased the length of the condylar process (P = 0.001) as well as the volume of the condylar neck (P = 0.001) and head (P = 0.006). The soft diet decreased the volume of the condylar neck (P < 0.001) and head (P < 0.001) two to three times more than the bite-blocks but did not affect the condylar process length. The interaction between the two variables was not statistically significant.
Both the bite-block appliance and weak masticatory muscle function reduced the volume at all regions of the condylar process, although the functional factor had a substantially greater effect. However, only the bite-block appliance affected the condylar process length. In the presence of both factors, an additive effect was found but no interaction detected.
除了咬块对牙齿位置的主要影响外，它们还可能影响下颌髁突的生长。我们的目的是研究在不同咀嚼力的情况下，咬块对髁突形态的影响。
将52只4周龄雄性大鼠分为硬食组和软食组，以建立具有不同咀嚼肌能力的个体。两周后，将它们平均分为咬块组和对照组。在总共6周的实验时间后，处死动物。用高分辨率微型计算机断层扫描对下颌骨进行扫描，并对髁突颈部和髁突头部进行三维分析。测量髁突的体积和长度。采用单因素方差分析进行统计学分析。
使用咬块可使髁突长度缩短（P = 0.001），同时髁突颈部（P = 0.001）和髁突头部（P = 0.006）的体积减小。软食使髁突颈部（P < 0.001）和髁突头部（P < 0.001）的体积减小幅度比咬块组多两到三倍，但对髁突长度没有影响。两个变量之间的相互作用无统计学意义。
咬块矫治器和较弱的咀嚼肌功能均会使髁突各区域的体积减小，尽管功能因素的影响要大得多。然而，只有咬块矫治器会影响髁突长度。在两种因素同时存在的情况下，发现有相加效应，但未检测到相互作用。
