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The curve of Spee is an important characteristic in the mandibular arch. An optimal occlusion must have a curve of Spee ranging from flat to mild. Therefore, an understanding of the curve of Spee is essential for both diagnosis and treatment planning in orthodontics. The aim of this study was to examine the difference in both the form and depth of the curve of Spee among class I, II, and III malocclusions and investigate the relationship between the depth of the curve of Spee with both overjet and overbite among patients at the University of North Sumatera Dental Hospital. A total of 100 dental study models with ages older than 15 years were enrolled and divided into 5 malocclusion groups: class I (n = 40), class II division 1 (n = 32), class II division 2 (n = 10), class II subdivision (n = 7), and class III (n = 11). The depth of the curve of Spee, overjet, and overbite was measured on dental study models with a digital caliper. The depth of curve of Spee was taken as the mean measurement from both sides of the arch on dental study models. The correlation coefficient between the depth of the curve of Spee and other variables were also calculated. The results showed that a maximum mean depth of the curve of Spee of 4.65 ± 1.41 mm in the class II division 2 group and a minimum depth of 2.34 ± 0.96 mm in the class III group. A statistically significant correlation was also found between the depth of the curve of Spee with both overbite and overjet. In conclusion, the curve of Spee was found to be deepest in class II division 2 followed by class II division 1, class II subdivision, class I, and class III malocclusion.

Context: Histological quantification of osteoclasts and osteoblasts can evaluate biological responses to orthodontic tooth movement. Histological analysis of bone samples can be technically challenging. Aims: To evaluate the differences between hematoxylin and eosin (HE) staining and immunohistochemistry (IHC) in quantifying osteoblast and osteoclast cells following the application of static orthodontic force. Methods: Orthodontic force was applied using a rubber separator around the maxilla incisor of Cavia porcellus. Tooth samples were taken at 0, 4, 8, 14, 21, and 28 days after applying orthodontic force. HE and IHC staining quantify osteoblast and osteoclast cells in the alveolar bone. IHC staining, i.e., Tartrate-resistant acid phosphatase (TRAP) staining, was used to identify osteoclasts, and osteocalcin (OCN) staining was used to identify osteoblasts. Results: Significantly higher numbers of osteoclasts and osteoblasts were observed with IHC compared to HE staining (p<0.05). Significant positive linear correlations in the numbers of osteoclasts (r = 0.757) and osteoblasts (r = 0.622) identified were observed between IHC and HE staining. Conclusions: The results of this study indicate HE staining may represent an acceptable alternative method of quantifying osteoclasts and osteoblasts in the preliminary research of orthodontic tooth movement (OTM).

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