IADR Abstract Archives
Three-Dimensional Changes Obtained From Damon and Hyrax Expansion Appliances
Objectives: Determine three-dimensional skeletal and dental changes in the expansion phase of orthodontic treatments using a Tooth-Anchored (Hyrax) expansion appliance versus the Damon system.
Methods: Cone-beam computed tomography (CBCT) from 40 patients treated for maxillary expansions were analyzed. These patients were randomly assigned to one of two groups (20 in the Tooth-Anchored group and 20 in the Damon system group). CBCTs were viewed and analyzed using the software platform AVIZO®. Forty-nine landmarks were chosen, defined and then placed on the initial and six month recall CBCT images for each patient. Landmark coordinates were obtained and analyzed using linear and angular measurements. Prior to this, ten additional images were first analyzed three times each to determine the reliability and measurement error of each landmark using Intraclass Correlation Coefficient (ICC). Descriptive statistics, ANOVA and paired t-tests were used for statistical analysis.
Results: ICC values were excellent for all landmarks in all axes (≥0.998) with the lowest value for the right greater palatine foramen landmark in the z-axis. The greatest measurement error was seen in the y-axis of the buccal alveolar cortical bone landmark of the left upper first molar (0.76±0.76mm). ANOVA testing showed there to be a statistically significant difference between the two techniques in expanding the maxilla (P<0.05). Damon system showed a mean increase of 2.24±1.82mm between the mesiobuccal pulp horns of the upper first molars (UMBP) but showed a 1.21±1.45mm decrease between the mesiobuccal pulp horns of the lower first molars (LMBP) whereas the Tooth-Anchored system showed a 5.79±1.90mm increase between UMBP and no significant change between the LMBP.
Conclusions: Both techniques expanded the maxilla. The Tooth-Anchored appliance demonstrated greater overall maxillary expansion than the Damon system in the six month expansion phase. However, the Damon system caused greater lingual tipping of the lower molars.
Methods: Cone-beam computed tomography (CBCT) from 40 patients treated for maxillary expansions were analyzed. These patients were randomly assigned to one of two groups (20 in the Tooth-Anchored group and 20 in the Damon system group). CBCTs were viewed and analyzed using the software platform AVIZO®. Forty-nine landmarks were chosen, defined and then placed on the initial and six month recall CBCT images for each patient. Landmark coordinates were obtained and analyzed using linear and angular measurements. Prior to this, ten additional images were first analyzed three times each to determine the reliability and measurement error of each landmark using Intraclass Correlation Coefficient (ICC). Descriptive statistics, ANOVA and paired t-tests were used for statistical analysis.
Results: ICC values were excellent for all landmarks in all axes (≥0.998) with the lowest value for the right greater palatine foramen landmark in the z-axis. The greatest measurement error was seen in the y-axis of the buccal alveolar cortical bone landmark of the left upper first molar (0.76±0.76mm). ANOVA testing showed there to be a statistically significant difference between the two techniques in expanding the maxilla (P<0.05). Damon system showed a mean increase of 2.24±1.82mm between the mesiobuccal pulp horns of the upper first molars (UMBP) but showed a 1.21±1.45mm decrease between the mesiobuccal pulp horns of the lower first molars (LMBP) whereas the Tooth-Anchored system showed a 5.79±1.90mm increase between UMBP and no significant change between the LMBP.
Conclusions: Both techniques expanded the maxilla. The Tooth-Anchored appliance demonstrated greater overall maxillary expansion than the Damon system in the six month expansion phase. However, the Damon system caused greater lingual tipping of the lower molars.