Computer-aided design and manufacture of hyrax devices: Can we really go digital?

The aim of this pilot study was to illustrate the feasibility of a new digital procedure to fabricate metallic orthodontic appliances. Hyrax appliances for rapid palatal expansion were produced for 3 patients using a CAD/CAM procedure without physical impressions or printed models. The work flow consisted of intraoral scanning, digital design with incorporation of a scanned prefabricated expansion screw, direct 3-dimensional metal printing via laser melting, welding of an expansion screw, insertion, and finally activation in the patients' mouths. Finite element analyses of the actual hyrax appliances were performed to ensure that the printable material used in combination with the chosen design would withstand the stress generated during activation. The results of these analyses were positive. The clinical results showed that this procedure is an efficient and viable digital way for constructing metallic orthodontic appliances. The flexibility of the digital appliance design, together with the biocompatibility and strength of the chosen material, offers a huge potential for more advanced appliance design.

Effects of short- and long-term celecoxib on orthodontic tooth movement.

OBJECTIVE: To test the hypothesis that short- and long-term celecoxib administration has no effect on orthodontic tooth movement. MATERIALS AND METHODS: Male Wistar rats were submitted to short- (3 days) and long-term (14 days) celecoxib administration, while the respective control groups received equivolumetric saline intraperitoneal injections. The upper left first molars of all rats were moved mesially for 14 days by a fixed orthodontic appliance exerting 50 g force upon insertion. After the experimental period, tooth movement was quantified and tissues around the first molar were processed for tartrate-resistant acid phosphatase (TRAP) histochemistry. The amount of tooth movement and the number of TRAP-positive cells on the alveolar bone surface were evaluated. RESULTS: The amount of tooth movement was significantly reduced in rats submitted to short- and long-term celecoxib administration, while the number of osteoclasts on the alveolar bone did not differ between the four groups studied. CONCLUSIONS: The hypothesis is rejected. Although celecoxib administration did not affect the number of osteoclasts, the osteoclast activity might be reduced, which could explain the inhibition of tooth movement observed in the celecoxib-treated animals. These results indicate that orthodontists should be aware of patients under short- and long-term therapy with celecoxib.

Evaluation of stress biomarkers and electrolytes in saliva of patients undergoing fixed orthodontic treatment.

BACKGROUND: The aim of this study was to test the hypothesis that treatment with orthodontic appliances evokes significant functional limitations and emotional stress, which can be detected by salivary biomarkers. METHODS: Twenty subjects (10 men and 10 women) who underwent orthodontic treatment were included in this prospective study. Saliva was sampled for detection of alpha-amylase activity and cortisol levels at three different times: before bracket placement (T0), 24 hours after archwire placement (T1), and 30 days after archwire placement (T2). The saliva electrolytes concentrations of calcium, phosphorus, magnesium, sodium and potassium were also evaluated. Moreover, the possible functional limitations of the appliances were evaluated by a masticatory performance test and pain experience registration. All variables were compared with those in a control group with normal occlusion. RESULTS: The orthodontic patients exhibited a significant increase in emotional stress as detected by the alpha-amylase activity at T1, the period in which patients reported the higher values of pain and exhibited the lower masticatory performance indices. The basal salivary cortisol was not affect by the treatment and the main change detected in electrolyte concentration was a sodium reduction, when these patients were compared to controls. CONCLUSIONS: The present data indicate that orthodontic patients are under emotional stress only during the period of higher pain experience, which could also disrupt the masticatory performance. However, these alterations were not correlated with a single measurement of stress-related biomarkers in saliva, suggesting that these solitary endocrine measurements are not adequate to predict the temporary pain and masticatory limitation experimented by patients undergoing orthodontic treatment.