Relationship between the Inclination of Adjacent Teeth Caused by Vertical Malposition of the Second Primary Molar – in Relation to Development Stage of First Molar

Aims: Mesial inclination of first molar caused by vertical malposition of the second primary molar is often untreated but this may create severe problems. To obtain an objective guideline for treatment of such cases, the relationship between degree of mesial inclination and developmental phase of first molar was analyzed. Study Design: Ten boys and six girls who exhibited vertical malposition of the second primary molar were analyzed. At their first visit oral checklists and panoramic radiographs were obtained. Methodology: Oral checklists were used at their first visit and panoramic radiographs were taken by Veraview Epocs X-550 (Morita/Kyoto). The radiographs were output as films by DRY PIX7000 (Fujifilm Medical/Tokyo). Examinations were conducted on the degree of development of the second bicuspid germ affected by a submerged second deciduous tooth, the presence of malposition, the degree of development of first molar and presence of tooth root resorption in the second primary molar, based on the panoramic radiographs. Results: A significant positive correlation occurred between (i) second primary molar space and degree of formation of the first molar (p<0.01); (ii) the angle between tooth axes of the first primary molar and first molar and amount of formation of the first molar (p<0.05); The vertical positional relationship between the second primary molar and the second bicuspid germ Proximity values showed larger values on the affected side; Retarded formation by 54% was recognized in the formation of the second bicuspid. Conclusion: The prognosis for treatment success may depend on the degree of first molar formation.