@齒顎矯正的迷思~6 buccal corridor(頰齒間隙) @ 崇愛牙醫診所(資料重建中,歡迎新舊朋友)

6)buccal corridor(=Lateral Negative Space “LNS”)頰齒間隙

~~圖裡的((B-A)
/ B )buccal corridor

在維基百科裡對buccal corridor
width有著以下的定義:

buccal corridor width (buk´l kor´idr),

n the negative space
between the buccal surface of the maxillary first premolar and the inner point
at which the lips join when the patient smiles. It is often stated as a ratio of
the inner lip commissure width divided by the distance between the first
maxillary premolars.

九種不同的微笑所顯現的buccal corridor spaces

Dr.
Charles Burstone Common Myths in Orthodontics (裡面談論到buccal corridor)

The smile
and buccal corridors (Dr. Burstone reviewed a number of photos to make
the following points).

1. Buccal corridors are very prevalent in the smiles of actors and
actresses.

2. Their size depends on the amount (width) of the
smile.

3. Their size depends on how the photograph is taken or the
view of the face.

4. Their size depends on the amount of mandibular opening.

5. The width of the dental arches is only one of many
factors involved in the presence of buccal corridors during
smile.

The battle for the skeletal modification of the
face – maxillary orthopedics

1. Dr. Burstone cited a study by Tanne et al.
which showed the treatment effects of maxillary protraction
headgear are largely dental with clockwise rotation of the mandible.
Tanne K, Sakuda M. Biomechanical and clinical changes of the craniofacial
complex from orthopedic maxillary protraction. Angle Orthod. 1991
Summer;61(2):145-52.

2. Dr. Burstone also discussed a case report of
maxillary protraction using an implant as anchorage for the protraction. The
results showed improvement in lip posture. Cephalometric evaluation showed
lingual inclination of the lower incisors from the effect of the chin cap and
clockwise rotation of the mandible. No maxillary skeletal effect was seen.

Why is
evidenced-based treatment not practiced?

1. Traditions, emotions, beliefs, commercialism,
gurus, easy-learning, appliance worship all contribute to the lack of
evidenced-based treatment in our specialty.

2. In research, evidence is clouded by sampling
methods, traditions, and tendencies to follow authority figures.

3. Epidemiologic data has limits with regard to
understanding the mechanism of response to treatment. Scientific understanding
of the mechanism is essential to solid evidence-based treatment.

Buccal corridor refers to the dark space (negative space) visible
during smile formation between the
corners of the mouth and the cheek-side surfaces of the upper
teeth.(嘴角與上排牙齒的頰側面之間所呈現的陰影部份)

Its appearance is influenced by:(它會受到以下的因素而顯現不同的情形)

the width of the smile and the upper arch. (微笑的寬度與上顎牙弓)
the tone of the facial muscles. (顏面肌肉的張力)
the positioning of the labial surfaces of the upper premolars.
(上顎小臼齒唇側面的位置)
the prominence of the canines, particularly toward the back of the
tooth. (犬齒的突度,尤其是與後面牙齒相比較)
any discrepancy between the value (brightness) of the premolars and
the six front teeth. (任何與前面6顆前牙與小臼齒明亮度的差異)

Arch form (牙弓型態)has a direct influence on the buccal
corridor(會直接影響頰齒間隙). The ideal arch is broad
and conforms to a U shape.(理想的牙弓是一U型的形狀) A narrow
arch is generally unattractive(窄的牙弓通常較不具吸引力). It disrupts the principles of
golden proportion(黃金比例) and makes the centrals appear far too dominant.

Patients with very narrow arches(窄的牙弓) may require orthodontics and possibly
surgical intervention prior to restoration in order to achieve excellent
results. The unattractive, negative space should be kept to a minimum. This
problem can be solved or minimized by restoring the premolars. The buccal
corridor should not be eliminated completely because a hint of negative space
imparts to the smile a suggestion of depth.

The negative space is often accentuated when only the six upper front
teeth are restored. The improvements in hue and value of these newly restored
teeth often exaggerates the sense of depth, darkness and prominence of the
buccal corridor. Because of this concern, it is advisable in some cosmetic cases
to include the premolars in the restorative plan. buccal corridor的差異圖例