Panoramic radiographs: determination of mandibular steepness

The aim of this study was to evaluate the potential of panoramic radiographs to measure mandibular inclination and steepness. Standardized panoramic and lateral cephalometric radiographs were taken for 95 subjects (46 females, mean age 12.4 ± 1.2 years; 49 males, mean age 12.1 ± 1.3 years). Mandibu-lar inclination from panoramic radiograph was measured using gonial angle formed by the tangents of the lower border of the mandible and the distal border of the ascending ramus and the condyle.

A correlation test was performed to check for similarity between the measurements. The mean val-ues for the gonial angle were 127.3 ± 6.2 and 125.7 ± 6.5 degrees measured from the panoramic and cephalometric radiographs respectively. A high correlation between the measurements taken from both radiographs was found (r=0.83, P<0.001). Panoramic radiographs are a useful tool for the mea-surement of gonial angle, which is an indicator of manibular steepness and subsequently mandibular growth direction. The ability to determine growth direction from the orthopantomogram will be use-ful because majority of dentists request an OPG for patients during routine dental examination. This will enable the dental professional to spot vertical growth problems using a readily available tool.

1. Friedland B. Clinical radiological issues in orthodontic practice. Sem Orthod 4: 64-78, 1998.

2. Mattila K, Altonen M, Haavikko K. Determination of the gonial angle from the orthopantomogram. Angle Orthod 47: 107-110, 1977.

3. Paulsen HU Morphological changes of the TMJ condyles of 1000 patients treated with Herbst appliance in the period of puberty to adulthood: a long-term radiographic study. Eur J Orthod 19:

657- 668, 1997.

4. Björk A. Variations in the growth pattern of the human mandible: longitudinal radiographic study by the implant method. J Dent Res 1: 400-411, 1963.

5. Larheim TA, Svanaes DB. Reproducibility of rotational panoramic radiography: mandibular linear dimensions and angles. Am J Orthod Dentofacial Orthop 90: 45-51, 1986.

6. Dahlberg G. Statistical methods for medical and biological students. London George Allen and Unwin Ltd, 1940.

7. Houston WJB. The analysis of errors in orthodontic measure-ments. Am J Orthod 83: 382-390, 1983.

8. Akcam MO,Altiok T, Ozdiler E. Panoramic radiographs: a tool for investigating skeletal pattern. Am J Orthod Dentofacial Ortho 123: 175-181, 2003.

9. Türp JC, Vach W, Harbich K, Alt KW, Sturb JR. Determining mandibular condyle and ramus height with the help of an ortho-pantomogram- a valid method? J Oral Rehab 23: 395-400, 1996.