Early vs late orthodontic treatment of deepbite: A prospective clinical trial in growing subjects

Introduction

The aim of this prospective clinical trial was to compare the outcomes of prepubertal vs pubertal treatment of deepbite patients with a protocol including biteplane and fixed appliances.

Methods

A sample of 58 subjects with deepbite completed the study. A total of 34 subjects received treatment with removable biteplane appliances in the mixed dentition at a prepubertal stage of skeletal maturation (early treatment group), and 24 subjects were treated at a pubertal stage of skeletal maturation in the permanent dentition (late treatment group). All subjects of both groups were reevaluated after an average period of 15 months after the completion of fixed appliance therapy. Treatment outcomes were assessed statistically after a phase with removable biteplane appliances and at the posttreatment observation.

Results

Treatment duration was significantly shorter in the early treatment group than in the late treatment group. Overbite reduction was significantly greater in the late treatment group (−3.1 mm) than in the early treatment group (−1.4 mm). In the late treatment group, 92% of the patients had a corrected overbite 1 year after therapy.

Conclusions

Treatment of deepbite at puberty in the permanent dentition leads to significantly more favorable outcomes than treatment before puberty in the mixed dentition.

Clinical trials reporting the results of orthopedic or orthodontic treatment specifically aimed at deepbite correction are scarce in the literature, and they usually lack comparisons between different treatment approaches or modalities. The general outcome of these investigations is that active treatment can induce a moderate improvement of the overbite followed usually by a relapse tendency.

No definitive information can be derived when evaluating the possible effects of treatment timing on deepbite treatment results. Tulloch et al found no significant impact on overbite change of phase 1 therapy followed by phase 2 treatment vs a single-phase orthodontic approach. However, they did not investigate deepbite treatment specifically. The long-term stability of deepbite treatment results was good for the sample studied more recently by Schütz-Fransson et al ; their subjects had started treatment in the early permanent dentition at a mean age of 12.2 years. Simons and Joondeph found that “deep bite patients of either sex in whom overbite reduction was accomplished during their respective pubertal growth spurt periods maintained this correction 10 years post-retention. Thus, it would be advisable for the clinician to be aware of individual differences in the onset of maximum growth velocity and to utilize this information in treatment planning.” A specifically designed clinical trial targeting patients with deepbite malocclusions treated at different developmental stages appeared to be required to compare possible outcomes of early vs late treatment of growing deepbite patients.

A classic treatment protocol for the correction of deepbite in growing subjects, especially in those who also have a Class II malocclusion, consists of the use of biteplane appliances, with or without the addition of headgear, followed by fixed appliance therapy to refine the occlusion and maintain the occlusal modifications. Therapy with anterior biteplanes is intended to limit the extrusion of the incisors and increase the length of the mandibular ramus relative to the eruption rate of the posterior teeth. In general, treatment of a deepbite in growing subjects appears to be indicated when they have an “impinging overbite,” a situation with overeruption of both the maxillary and mandibular anterior teeth and an accentuated curve of Spee. In this type of deepbite, the mandibular incisors often contact the palatal tissue behind the maxillary anterior teeth, occasionally resulting in a long-term periodontal breakdown. Deepbite, in particular when associated with retroclined maxillary incisors, can also be a risk factor for temporomandibular disorders.

The aim of this prospective clinical trial was to assess the outcomes of early vs late treatment of deepbite patients by means of anterior biteplane appliances followed by fixed appliance therapy. The early treatment approach to deepbite in the mixed dentition at a prepubertal stage of skeletal maturation was compared with a late treatment approach to the malocclusion in the permanent dentition at a pubertal stage of skeletal maturation.

Material and methods

A total of 58 patients were enrolled for this trial at the Department of Orthodontics of Università degli Studi di Firenze in Florence, Italy. At the initial observation, the subjects had to have a deepbite (overbite, >4.5 mm), fully erupted maxillary and mandibular incisors, no multiple tooth agenesis or agenesis affecting the permanent incisors, and no craniofacial syndromes. The numbers for the sample derived from a previous estimate of sample size based on a power analysis. To achieve a power of the study exceeding 0.9, calculated for an effect size equal to 1.15 at an α level of 0.05, each group of patients under investigation had to include 24 subjects or more.

The early treatment group comprised 34 subjects, and the late treatment group included 24 subjects. The early treatment subjects started treatment in the mixed dentition at a prepubertal stage of individual skeletal maturation (CS 1 or CS 2), and the late treatment patients started orthodontic therapy in the permanent dentition at a pubertal growth stage (CS 3 or CS 4). Table I reports the distribution of the 2 groups for sex, stages of skeletal maturation, and dentoskeletal discrepancies.

Table I
Demographics of the early and late treatment groups
Age at T1 (y) Age at T2 (y) Age at T3 (y) T1-T2 interval (y) T2-T3 interval (y) T1-T3 interval (y)
Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD
Early treatment group
(n = 34; 17 girls, 17 boys)
Class II Division 1, 14 subjects
Class II Division 2, 7 subjects
Class I, 13 subjects
CS at T1: CS 1, 28 subjects
CS 2, 6 subjects
CS at T2: CS 3, 23 subjects
CS 4, 11 subjects
CS at T3: CS 5, 8 subjects
CS 6, 26 subjects
10.7 1.6 13.1 1.3 15.4 1.8 2.9 1.3 2.5 1.5 5.6 2.0
Late treatment group
(n = 24; 14 girls, 10 boys)
Class II Division 1, 8 subjects
Class II Division 2, 5 subjects
Class I, 11 subjects
CS at T1: CS 3, 18 subjects
CS 4, 6 subjects
CS at T2: CS 4, 10 subjects
CS 5, 14 subjects
CS at T3: CS 5, 3 subjects
CS 6, 21 subjects
12.3 0.9 13.8 0.8 15.7 0.9 1.4 0.9 2.7 0.9 4.3 1.6

CS , Cervical vertebral maturation stage.

In both groups, treatment of deepbite was accomplished with a nonextraction protocol that consisted of removable appliances in the form of anterior biteplane appliances followed by fixed appliance therapy to refine the occlusion. The early treatment patients underwent a first phase of treatment with either a removable maxillary plate with an anterior biteplane (26 subjects), or cervical headgear associated with an anterior biteplane (8 subjects). When the patients were showing permanent dentition, the second phase of therapy was accomplished with fixed appliances (0.022-in slot, preadjusted brackets). The duration of active phase 1 treatment was 18 months on average with a retention period before fixed appliances from 10 to 18 months during which the patients wore a removable maxillary plate with an anterior biteplane at night. The duration of active phase 2 treatment with fixed appliances was 18 months on average followed by a posttreatment retention period of 14 months on average. As a retention protocol, all subjects wore maxillary and mandibular Hawley retainers.

In the late treatment patients, orthodontic therapy started with a removable maxillary plate with an anterior biteplane (17 subjects) or with headgear associated with an anterior biteplane (7 subjects), and it was immediately followed by fixed appliances (0.022-in slot, preadjusted brackets). The duration of comprehensive treatment in the late treatment group was on average 31 months, with an initial phase of deepbite treatment of 15 months and a fixed appliance phase of 16 months. An average posttreatment retention period of 15 months followed active therapy in the late treatment group, during which the patients wore Hawley retainers in both arches.

Both treatment groups received a standardized protocol of fixed appliance therapy with the main purposes to level and align the dental arches and refine the occlusion. Treatment was ended when a satisfactory correction of the malocclusion had been reached.

Lateral cephalograms were taken of all patients before treatment (T1), before fixed appliance therapy (T2), and at least 1 year after active therapy with fixed appliances (T3). Most patients were at the end of active circumpubertal growth (CS 6) at T3 ( Table I ).

Cephalograms were traced by 1 investigator (L.F.) and then verified for landmark location, anatomic contours, and tracing superimpositions by a second (T.B.). Any disagreements were resolved by retracing the landmark or structure to the satisfaction of both observers. A customized digitization regimen and analysis (Viewbox 3.1; dHAL Software, Kifissia, Greece) were used for all cephalograms that were examined in this study.

The magnification of the lateral cephalograms was consistent at 8%. The examiners who analyzed the lateral cephalograms of all patients at T1, T2, and T3 were blinded to the origin of the films and the group to which each subject belonged.

A total of 40 lateral cephalograms randomly chosen from all observations were retraced in random order and redigitized to calculate the method error by means of Dahlberg’s formula. The operator (L.F.) who retraced and redigitized the cephalograms was blinded to time period and group. The error for linear measurements ranged from 0.25 mm (overjet) to 0.75 mm (pogonion to nasion perpendicular), and the error for angular measurements varied from 0.55° (Ar-Goi-Me) to 1.40° (interincisal angle).

Statistical analysis

Descriptive statistics of craniofacial measurements in both treated samples at T1, as well as the T1 to T2, T2 to T3, and T1 to T3 changes were calculated. The Kolmogorov-Smirnov test showed normality of distribution for the measurements used in the study. Therefore, parametric statistics (analysis of variance [ANOVA] with Tukey post-hoc tests, P <0.05) were used. The following comparisons were carried out for the dentoskeletal variables: (1) early vs late treatment groups at T1 (comparisons of starting forms); (2) T1 to T2 changes in the groups (effects of deepbite treatment protocols with anterior biteplane appliances); (3) T2 to T3 changes in the groups (effects of treatment with fixed appliances); and (4) T1 to T3 changes in the groups (effects of overall comprehensive treatment including a 1-year posttreatment observation period).

The duration of treatment expressed in months was compared between the groups by means of the Student t test for independent samples.

The prevalence rates of subjects showing correction of deepbite at T3 in the early treatment group vs the late treatment group were calculated and compared with a chi-square test. Correction of deepbite was assessed when the overbite value was smaller than 4 mm at T2.

All statistical computations, comparisons, and analyses were carried out with statistical software (version 17.0; SPSS, Chicago, Ill).

Results

No differences were found for the starting forms of the 2 groups, with a few exceptions ( Table II ). The ANS-Me measurement was greater in the late treatment group, as a consequence of the greater age at T1 in this group, and the mandibular incisors were less retruded to the Point A-pogonion line in the late treatment group as well.

Table II
Descriptive statistics and statistical comparisons of the starting forms
Cephalometric measures Early treatment group (n = 34) Late treatment group (n = 24) t Significance
Mean SD Mean SD
Skeletal sagittal
Point A to nasion perp (mm) 0.3 2.9 1.0 5.0 −0.597 NS
Pg to nasion perp (mm) −7.1 5.6 −6.4 6.3 −0.453 NS
Wits (mm) 0.8 3.0 −0.1 4.3 0.909 NS
Skeletal vertical
FH to palatal plane (°) −1.1 2.7 −2.3 4.0 1.354 NS
FH to mandibular plane (°) 23.2 5.6 23.7 5.0 −0.363 NS
Palatal plane to mandibular plane (°) 24.3 6.6 26.0 5.1 −1.059 NS
Ar to Goi (mm) 41.1 5.0 42.9 3.9 −1.523 NS
ANS to Me (mm) 61.2 4.4 65.0 3.8 −3.365
Ar-Goi-Me (°) 124.0 7.3 123.1 6.3 0.481 NS
S-Go/N-Me (%) 62.5 4.5 61.9 3.2 0.591 NS
Interdental
Overjet (mm) 5.8 2.5 5.9 1.5 −0.308 NS
Overbite (mm) 6.1 1.3 5.9 1.2 0.639 NS
Interincisal angle (°) 138.3 10.2 134.7 7.6 1.452 NS
Molar relationship (mm) −0.7 1.8 −0.1 2.2 −1.110 NS
Maxillary dentoalveolar
U1 to Point A vertical (mm) 3.8 2.2 4.4 1.9 −1.775 NS
U1 to FH (°) 108.0 8.6 108.7 5.8 −0.317 NS
Mandibular dentoalveolar
L1 to Point A-Pg (mm) −1.8 2.0 −0.1 2.1 −3.161
L1 to mandibular plane (°) 90.5 7.2 92.9 5.7 −1.369 NS
NS , Not significant; Perp , perpendicular.

P <0.01.

The effects of the first phase of treatment with anterior biteplane appliances (T1-T2 changes) are shown in Table III , with no significant differences between the 2 groups for the sagittal skeletal measures. The length of the mandibular ramus (Ar-Goi) showed increases that were greater in the early treatment group than in the late treatment group.

Table III
Descriptive statistics and statistical comparisons of the T1-T2 changes: effects of therapy with biteplane appliances
Cephalometric measures Early treatment group (n = 34) Late treatment group (n = 24) Net difference Significance
Mean SD Mean SD
Skeletal sagittal
Point A to nasion perp (mm) 0.3 2.7 0.5 2.0 −0.2 NS
Pg to nasion perp (mm) 2.9 3.9 1.8 3.7 1.1 NS
Wits (mm) −1.4 3.9 0.6 3.9 −2.0 NS
Skeletal vertical
FH to palatal plane (°) 0.8 2.7 −0.4 2.4 1.2 NS
FH to mandibular plane (°) −0.8 2.4 −0.1 2.4 −0.7 NS
Palatal plane to mandibular plane (°) −1.3 2.0 0.5 1.9 −1.6 NS
Ar to Goi (mm) 5.5 2.7 2.8 2.7 2.7
ANS to Me (mm) 4.9 3.1 3.3 2.2 1.6 NS
Ar-Goi-Me (°) −1.0 2.9 −0.4 3.0 −0.6 NS
S-Go/N-Me (%) 1.1 1.8 0.4 1.6 0.6 NS
Interdental
Overjet (mm) −1.1 2.3 −1.1 1.5 0.0 NS
Overbite (mm) −1.1 1.4 −2.3 1.6 1.2 NS
Interincisal angle (°) −3.4 12.1 −2.6 9.2 −0.8 NS
Molar relationship (mm) 2.6 2.8 1.8 2.4 0.8 NS
Maxillary dentoalveolar
U1 to Point A vertical (mm) 1.2 2.3 0.3 2.0 0.9 NS
U1 to FH (°) 2.6 8.9 2.0 7.2 0.6 NS
U1 vertical (mm) 1.1 1.8 −0.4 1.7 1.5
U6 vertical (mm) 2.7 1.6 1.1 1.3 1.6
Mandibular dentoalveolar
L1 to Point A-Pg (mm) 1.7 2.1 0.7 2.1 1.0 NS
L1 to mandibular plane (°) 1.5 6.0 0.7 4.7 0.8 NS
L1 vertical (mm) 3.0 1.8 1.4 1.5 1.6
L6 vertical (mm) 4.1 2.5 2.5 1.4 1.6 NS
NS , Not significant; Perp , perpendicular.

P <0.05.

As for the occlusal changes, overbite showed a 1.2-mm greater reduction in the late treatment group than in the early treatment group (although this difference was not statistically significant). Both the maxillary and mandibular incisors showed significant amounts of extrusion in the early treatment group when compared with the late treatment group, whereas the mandibular molars erupted significantly more in the early treatment group than in the late treatment group.

No significant differences between the groups were assessed as a result of the phase of treatment with fixed appliances followed by retention (T2-T3 changes; Table IV ).

Table IV
Descriptive statistics and statistical comparisons of the T2-T3 changes: effects of fixed appliance therapy
Cephalometric measures Early treatment group (n = 34) Late treatment group (n = 24) Net difference Significance
Mean SD Mean SD
Skeletal sagittal
Point A to nasion perp (mm) 0.1 2.3 0.2 3.3 −0.1 NS
Pg to nasion perp (mm) 1.0 3.8 0.3 5.2 0.7 NS
Wits (mm) 2.9 4.9 0.9 4.4 2.0 NS
Skeletal vertical
FH to palatal plane (°) 0.0 2.6 0.8 3.1 −0.8 NS
FH to mandibular plane (°) −1.1 2.6 −0.7 2.5 −0.4 NS
Palatal plane to mandibular plane (°) −1.1 2.4 −1.5 2.4 0.4 NS
Ar to Goi (mm) 3.6 3.5 3.2 4.6 0.4 NS
ANS to Me (mm) 3.1 2.5 2.9 3.5 0.2 NS
Ar-Goi-Me (°) −2.2 3.3 −1.9 3.4 −0.3 NS
S-Go/N-Me (%) 1.2 2.2 0.7 2.3 0.5 NS
Interdental
Overjet (mm) −0.5 1.6 −0.9 1.6 0.4 NS
Overbite (mm) −0.3 1.1 −0.9 1.3 0.6 NS
Interincisal angle (°) −2.4 7.8 −2.1 8.6 −0.3 NS
Molar relationship (mm) −0.8 2.2 −0.1 2.1 −0.7 NS
Maxillary dentoalveolar
U1 to Point A vertical (mm) 0.2 1.8 −0.5 1.9 0.7 NS
U1 to FH (°) 1.3 5.4 0.7 5.1 0.6 NS
U1 vertical (mm) 0.6 1.3 0.2 1.8 0.4 NS
U6 vertical (mm) 2.3 1.5 2.1 1.5 0.2 NS
Mandibular dentoalveolar
L1 to Point A-Pg (mm) 0.5 1.5 0.6 1.8 −0.1 NS
L1 to mandibular plane (°) 2.3 5.1 2.1 5.9 0.2 NS
L1 vertical (mm) 1.7 1.7 1.8 2.5 −0.1 NS
L6 vertical (mm) 1.8 2.1 2.2 2.5 −0.4 NS
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Apr 8, 2017 | Posted by in Orthodontics | Comments Off on Early vs late orthodontic treatment of deepbite: A prospective clinical trial in growing subjects
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