Development of the curve of Spee in Class II subdivision malocclusion: a longitudinal study

Long-term stability of curve of Spee depth among orthodontically treated patients: A retrospective longitudinal study

OBJECTIVE

The curve of Spee is deemed important characteristic of the dentition for a balanced occlusion and distribution of masticatory forces, while orthodontic levelling of an accentuated curve of Spee is generally included as a treatment goal for deepbite correction. However, relapse is often seen and can be problematic.

METHODS

A retrospective longitudinal study of predominantly young patients with a deep curve of Spee, who had been treated orthodontically with 0.018"-slot Edgewise fixed appliances, was performed. The depth of the curve of Spee was digitally measured before treatment (T1), at debond (T2), and an average of 7 years post-debond (T3) and analysed statistically at 5%.

RESULTS

A total of 157 patients were included (56.7% female; 11.6-year-old at T1), 16.6% of which were treated with premolars extractions. Non-extraction treatment reduced the curve of Spee at the first premolar from 1.87 mm (T1) to 0.22 mm (T2), which relapsed 0.12 mm (T3; P = .04). The respective depths for the second premolar were 2.0 mm (T1), reduced to 0.80 mm (T2). No significant relapse was seen for the second premolar (0.08 mm; P > .05) or the first permanent molar (0.06 mm; P > .05). No overall significant differences in absolute relapse were seen between extraction and non-extraction patients, but premolar extractions were associated with less clinically relevant relapse at the first molar (odds ratio 0.27; 95%-confidence interval 0.08-0.88; P = .003).

CONCLUSION

Steep curves of Spee can be satisfactorily levelled orthodontically with satisfactory stability in the long term, while premolar extractions might be associated with less relapse.

Comparative evaluation of the depth of curve of Spee between individuals with normal dentition and individuals with occlusal wear using conventional and digital software analysis techniques: An in vivo study

Objectives:

The objective of this study is to evaluate and compare the depth of curve of Spee in normal dentitions and dentitions with occlusal wear using conventional and digital software techniques.

Materials and Methods:

A total of 70 healthy human subjects were selected for this study in an age group of 20–50 years. Group A includes the stone models (dental casts) of 35 individuals with healthy (nonattrited) dentition. Group B includes stone models of 35 individuals with occlusal wear (generalized attrited) dentition. Two methods were used for measuring the curve of Spee, i.e., conventional method and three-dimensional digital analysis method.

Results:

Depth of the curve of Spee between these two groups was statistically the same. The Digital software analysis (Method II) gives more accurate readings when compared with the Conventional (Method I) of measuring the depth of the curve of Spee.

Conclusion:

Depth of curve of Spee is maintained through the life. There is no statistical difference in depth of curve of Spee between the two groups and digital method give more accurate measurements.