dc.description.abstract | The purpose of this prospective study was to determine whether dental intrusion
is effective in treating growing retrognathic hyperdivergent patients without negatively
affecting the roots and periodontal structures. The sample consisted of 17 (7 males and
10 females) consecutively treated patients who were 13.2 ±1.1 years old at the start of
treatment (T1) and treated for 25.3 ± 9.3 months (T2). The maxillary posterior teeth
(premolars and molars) were all intruded using a rigid segmental appliance. Two
maxillary and two mandibular MSIs (immediately loaded with 150gr coil springs) were
used for the intrusion mechanics and vertical control. A matched control group was used
to evaluate the skeletal changes that occurred during treatment. CBCT records, taken at
T1 and at the end of the orthopedic phase (T2) were used to evaluate the treatment
effects. The results showed significant (p<.05) intrusion (2.5 ± 1.7 mm) of the maxillary
dentition in the treated group. The mandibular plane angle closed 2° ±1.7° and the SNB
angle increased 1.5° ±1.5°. True forward rotation of the treated sample was significantly
(p<.05) greater (1.8°) than in the controls. The treated group showed greater superior and
less posterior condylar growth than the controls, but the difference was not statistically
significant. All of the maxillary roots showed statistically significant amounts of external
apical root resorption (EARR), ranging from 0.67 mm to 1.21 mm. Pointed roots showed
the greatest amounts of resorption, followed by bent roots, normal shaped roots, and
roots with open apices, which showed the least EARR. Alveolar crest heights between
first molar and second premolar decreased significantly (0.38 ± 0.6 mm) over time, and
the distance between the bone and the CEJ increased significantly (0.52 ± 0.9 mm) only
on the distal aspect of the maxillary second premolar. The overall MSI failure rate was
4.6%. It can be concluded that segmental intrusion of the posterior teeth with light forces
and skeletal anchorage is effective for treating growing retrognathic hyperdivergent
patients. The mechanics produced a significant true forward mandibular rotation, with
minimal loss of crestal bone height and clinically acceptable EARR of the teeth that
were intruded. | en |