20161109 principle and concept L2 by Percy Chang 陳明時 (part 2:VDO討論)

這堂課延續了上次principle, concept, and practice in prosthodontics-1989
上面這是一份ACP在1989年發表的, 各位可以到JPD自行下載。或是可以email給我，我會傳給你一份。
P.89 右邊

首先，先定義freeway space= interocclusal rest space。

Interocclusal rest space(GPT):the difference between the vertical dimension of rest and the vertical dimension while in occlusion

共有六種方法可以找到適當的VDO:

1.VDR-VDO=2-4mm

  但是這數字是class I jaw relationship, class 2: 0.5-1mm, class 3: 3-5mm

  由此可知, class 2病人可超作空間更有限！

2.closest speaking space:(GPT)

   the space between the anterior teeth that, according to Dr. Earl Pound, should not be more or less than 1 to 2 mm of clearance between the incisal edges of the teeth when the patient is unconsciously repeating the letter ‘‘S.’’ Dr. Meyer M. Silverman termed this speaking centric, which was defined as the closest relationship of the occlusal surfaces and incisal edges of the mandibular teeth to the maxillary teeth during function and rapid speech. This was later called closest speaking level by Dr. Silverman and finally the closest speaking space

    s sound: horizontal and vertical overlap大約1mm, 反正不可以撞到, 用發音來決定.

    補充: UCLA會建議排牙3-3, or 4-4較好，因為看1st premolar垂直分離比較準。

3.Proprioception or choice by patient

    Proprioception (GPT)：the reception of stimulation(冷熱, 酸甜,碰撞大小, 觸覺, 吞嚥) of sensory nerve terminals within the tissues of the body that give information concerning movements and the position of the body; perception mediated by proprioceptors. 此為反射動作, 

4.Swallowing on soft wax cones

吞嚥容易度, 牙齒碰到才能吞嚥，所以CR時muscle最放鬆才能吞嚥但只有短暫時間，所以用吞嚥抓CR不容易。 

（測量）是否在CR: 吞嚥時容易與否 

但是有個致命缺點:  大都受到舌頭影響

5.Relative parallelism of ridges

increase or decrease too much: openbite(diversity) or posterior decrease (conversion)

補充: 怎麼定義occlusal plan是門大學問, 但是根據Dr. Beumer給的tip: 先確定門牙位置（可以依照rest position時, 門牙露出1mm; f sound, incisal edge touch wet-dry line)

6.General appearance of the midface profile

口角不可以內塌，不然會造成angular cheilitis