Transverse assessment with a CBCT, is it the answer? 5 MINUTE SUMMARY

orthodontics In summary

Join me for a look at CBCT and its use in the diagnosis of the transverse problem, and if it offers the solution to the debated topic. The podcast is based on a lecture by Chun Hsi Chung at this year’s AAO and appraises established methods of assessment, the Curve of Wilson and the WALA ridge line through the lens of a CBCT, as well as how to use a CBCT to assess the maxilla and mandible, which although revealed an ideal measurement, may not be telling the full story.

What is ideal?

inclination

Curve of Wilson – CBCT study

• Vertical distance buccal and lingual cusp, 1mm vertical difference

• Buccal inclination upper 5 degrees Alkhatib 2017

• Lingual inclination lower 12 degrees Alkhatib 2017

Andrews WALA ridge 2000

• Bucco-lingual distance from crown ( FA point) to the most prominent portion of mandibular buccal alveolar bone (coincident with mucogingival junction)

• Hypothesised teeth over the basal bone , Glass 2019

• 1st molar = 2mm

• Ideal mandibular intermolar width FA – FA = WALA-WALA distance minus 4mm

Normal width CBCT

CBCT age 13 N = 79 Miner 2012

• Maxilla slightly smaller

• mid point molar root on lingual bone -1.22 +/- 2.91mm

CBCT Age 22.7 years Koo 2017

• Measure CoR furcation 1st molar Mx – Mn = -0.39+/- 1.87mm

CBCT 56 adults normal occlusion Lee 2022 PENN STUDY

• Buccal – buccal on crestal bone, furcation, 6s

• Lingual – lingual crestal furcation 6s

• Reliable reading on lingual aspect – buccal shelf bone prevents reliable readings

• Maxilla narrower than mandible -1 +/- 3mm

• Previous literature Tamburrino 2010 describes 5mm cortical plate level of furcation buccal aspect, however Lee 2022 showed for males 1.1mm +/- 4.5mm and 1.6mm +/- 2.9mm

Without cbct can transverse diagnosis occur?

• Models = lingual surface at furcation level (4mm vertical below gingival margin) maxillary width slightly narrower than mandible -2+/- 3mm

Issue with CBCT for diagnosis

• Standard Deviation is large = +/- 3mm, range from -4mm-+2mm falls into SD

Issue with study model transverse analysis from 4mm at the gingiva

• Not validated