重量：1.5Kg 頁數：296  裝訂：精裝 　開數：22 x 29.4 cm   印刷：彩色

圖：865

表：19

Preface

Many interesting phenomena have come into sight through long-term follow-up of many treated cases over a period of 40 years. The occlusion changes with posttreatment growth, jaw movement, muscle status (tongue, perioral, masticatory and cervical muscles) and respiratory pattern. In other words, the teeth will move posttreatment, causing changes in torque, occlusal plane, etc. When function is restored at an early stage of orthodontic treatment, the teeth can be properly positioned to favorably affect subsequent growth and development and allow the formation of a functionally and esthetically balanced maxillofacial skeleton. The form of occlusion established at the end of active treatment will not remain the same, particularly in patients with long-term occlusal stability. Instead, the teeth will find

their own places for stability by accommodating to changes due to growth and jaw movement until a functional occlusion is established with proper anterior guidance, posterior guidance and condylar guidance.

What concerns us as orthodontists most seems to be patient compliance, treatment time and posttreatment stability. I wonder if you have seen occlusal instability develop only a couple of years posttreatment, even after an extended treatment time of 3 to 5 years. Can this be classified as a genetically caused relapse or a relapse caused by posttreatment growth and development? Have you experienced postorthodontic occlusal instability in nongrowing adult patients as well?

What has been overlooked in our orthodontic treatment? We may have failed to recognize the merit of the function inherent in the human body because of our overdependence on mechanotherapy. My clinical experience suggests that failure to respect basic physiologic functions such as respiration and perioral muscle function when performing occlusal treatment would give rise to not only the problem of relapse but also adverse effects on posttreatment growth and jaw function.

• I have learned through a number of cases treated over the years that it is diffìcult to solve orthodontic problems with mechanotherapy alone. In light of adverse effects with extended use of retainers, the most effective and physiologic approach to retention would be to gain adequate tongue space for nasal respiration at an early stage of treatment and restore