The impact of the loss of first permanent molars on the duration of treatment in patients treated with orthodontic space closure and without skeletal anchorage

Abstract

Background This study aims to evaluate the impact of the loss of permanent molars on the duration of orthodontic treatment for space closure and without skeletal anchorage. Methods Records at the beginning (T0) and the end (T1) of orthodontic treatment were selected retrospectively. Patients were divided into two groups: loss of molar (n = 19) and control, without loss (n = 24). The impact of loss on treatment time was assessed using multiple linear regression adjusted for the number of absences, bonding failures, age, sex, PAR index at T0 and T1 at p<0.05. Treatment time was also evaluated by the number of losses and which arches were involved (upper, lower). The systematic and random errors for the PAR index were verified using the intraclass correlation coefficient (ICC) and the Dahlberg formula, respectively. Results A small random error (1.51) and excellent replicability (ICC = 99.6) were observed. Overall average treatment time was 22.5 months (± 7.95) for the group without loss and 44.7 months (± 17.3) with a loss. Treatment time was longer in cases where there was a higher number of missing molars and when both arches were involved. In addition to the loss (β = 4.25, p < 0.001), the number of missed appointments (β = 2.88, p < 0.001) had a significant effect and increased treatment time. Bonding failures, gender, age, and PAR index at T0 and T1 were not significantly associated with treatment time in the multivariate model (p > 0.05). Conclusion Loss of the first permanent molar has a negative impact on orthodontic treatment time in cases of space closure. The treatment time is longer when there are more tooth losses and arches involved. Treatment time also increases with greater numbers of missed clinical appointments.

The impact of COVID-19 pandemic on total treatment time of fixed appliances

“…This can be explained not only by the low number of patients without missing teeth, but also by the choice of the orthodontist in most of the cases to keep the spaces for later prosthetic rehabilitation. The initial malocclusion was also not statistically significant in this study, corroborating other findings [9,10,[31][32][33][34]. However, some studies have identified an influence of initial malocclusion on the treatment time variability [35][36][37], demonstrating that its prediction remains an inexact science and depends on numerous factors.…”

“…In general, the present sample had few patients with missing teeth, despite this being a common clinical presentation, especially related to molar loss [30]. It has already been shown that patients with loss of permanent molars associated with space closure may have longer treatment times compared to patients without tooth loss [31]. In this study, this variable had no impact on treatment time.…”

“…Previous studies [9,31,37] found no association in the quality of finished treatment with an increase or reduction of treatment time, while another two [38,39] found a longer treatment time in cases with reduced clinical results. This can be justified by an "exhaustion of the patient" and consequent less collaboration or poor planning of the case.…”

Criteria for early diagnosis of mandibular third molar agenesis based on the developmental stages of mandibular canine, first and second premolars, and second molar: a retrospective cohort study

“…Even if the mandibular first molar is extracted early, L7 may exhibit a mesial inclination or L5 may exhibit a distal inclination, resulting in poor vertical occlusal contact. Further, if too much space remains in the lateral segment area, overbite may worsen due to the lingual tilting of the mandibular incisors [ 34 ]. Moreover, removal of the first molar can lead to skeletal changes such as mandibular asymmetry and rotation of the occlusal plane [ 35 , 36 ].…”

“…Based on these findings, if the first molar needs to be replaced by the third molar, comprehensive orthodontic treatment planning and the developmental stage of the second molar should be considered. In such cases, dentists should consider long-term orthodontic treatment if the first molar extraction space remains [ 34 ].…”