Stability of anterior open-bite treatment with occlusal adjustment

Introduction

In this study, we aimed to evaluate the long-term stability of anterior open-bite treatment with occlusal adjustment and the dentinal sensitivity caused by this procedure in the long term.

Methods

The sample comprised 17 open-bite patients who experienced relapse of the negative vertical overbite after orthodontic treatment and were retreated with occlusal adjustment. The cephalometric changes were evaluated on lateral cephalograms obtained before and after the occlusal adjustment and in the long term (mean, 3.4 years after occlusal adjustment). Dentinal sensitivity was also evaluated before the occlusal adjustment, and 1.35 months, 4.61 months, and 3.4 years later. The cephalometric statuses between the 3 evaluations were compared with analysis of variance (ANOVA) and Tukey tests. The percentages of clinically significant relapse were calculated. To compare dentinal sensitivity at the several stages, nonparametric Friedman and Wilcoxon tests were performed.

Results

Statistically significant relapse of anterior open bite occurred in 33.3% of the patients. Those who had the procedure before 21 years of age were most likely to experience relapse. Dentinal sensitivity remained within the normal range in the long term.

Conclusions

Despite the statistically significant relapse of anterior open bite, clinically significant stability was found in 66.7% of the patients.

An open-bite malocclusion in the permanent dentition is difficult to treat and often has significant relapse after orthodontic correction. Stability of anterior open-bite correction in extraction patients is greater than in nonextraction patients.

Some patients with relapse of anterior open bite can be retreated with occlusal adjustment. The occlusal adjustment procedure to correct open bite in relapsed orthodontic patients produces counterclockwise rotation of the mandible, improvement in the maxillomandibular relationship, increased overbite, and reduced facial convexity.

Because no orthodontic tooth movement is required to close the bite, it is speculated that this unusual treatment alternative can provide more stable results than orthodontic treatment, although this has not been systematically investigated. Therefore, the objective of this study was to evaluate the long-term stability of anterior open-bite treatment with occlusal adjustment and the dentinal sensitivity in the long term.

Material and methods

The sample consisted of 17 patients (7 male, 10 female), obtained from the files of the Department of Orthodontics at Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil. All patients originally had an anterior open-bite malocclusion, had undergone orthodontic treatment with fixed appliances, had anterior open-bite relapse after a mean posttreatment period of 4.15 years (range, 1-6 years), and were retreated with the occlusal adjustment procedure. The patients’ mean age when the procedure was performed was 21.53 years (SD, 4.19 years; range, 17.58-31.50 years). After the occlusal adjustment, their mean age was 21.67 years (SD, 4.19; range, 17.66-31.58 years); in the long term, the mean age was 25.07 years (SD, 4.15; range, 21.00-35.00 years). The mean time of long-term evaluation was 3.40 years (SD, 0.17; range, 3.16-3.91 years). The occlusal adjustment procedure was performed in centric relation, according to the method of Okeson.

This study was approved by the Ethics in Research Committee of the University of São Paulo, Bauru, São Paulo, Brazil, and all subjects signed informed consent.

The cephalometric changes were evaluated on lateral cephalograms obtained before and after the occlusal adjustment and in the long term. The cephalometric tracings and landmark identifications were made on acetate paper by 1 investigator (M.V.C.) and then digitized with a digitizer (Numonics Accugrid XNT, Houston Instruments, Austin, Tex). These data were stored in a computer and analyzed with Dentofacial Planner (version 7.02, Dentofacial Planner Software, Toronto, Ontario, Canada), which corrected the image magnification factors of the lateral cephalograms that were between 6% and 9.8%.

All cephalometric measurements were described in our previous article.

Dentinal sensitivity was evaluated before the adjustment, after 1.35 months (SD, 0.45; range, 0.43-2.30 months), after 4.61 months (SD, 0.60; range, 2.63-5.20 months), and in the long term (3.4 years after the occlusal adjustment; SD, 0.17; range, 3.16-3.91), with the sensitivity test of Price et al. This test consists of a questionnaire used in the various stages to evaluate dentinal sensitivity of the equilibrated teeth. The level of sensitivity was evaluated in relation to mastication, heat, cold, citrus fruits, and percussion. The patients answered each question on a visual analog scale (0-10; 0 = no pain and 10 = the worst pain imaginable).

A month after the first measurements, 15 randomly selected cephalograms were retraced and remeasured by the same examiner (M.V.C.). Casual errors were calculated according to Dahlberg’s formula (Se ²= Σd ²/2n), where Se ²is the error variance and d is the difference between 2 determinations of the same variable. Systematic errors were evaluated with dependent t tests at P <0.05.

Statistical analysis

Because the sample included some patients who were still growing, it was divided into 2 subgroups to investigate growth influence in the results. One subgroup consisted of patients under 21 years of age, and the other of patients over that age when the occlusal adjustment was performed. The 3 evaluation stages were compared with dependent analysis of variance (ANOVA) followed by Tukey tests in the whole sample and the subgroups.

A clinically significant relapse of anterior open bite was defined as a negative overbite between the maxillary and mandibular incisors at the long-term evaluation. Therefore, to establish a clinical parameter as to the probability of open-bite correction stability with occlusal adjustment, the percentages of patients with and without clinically significant relapse were calculated from the number of patients who had positive overbites after the procedure.

To compare dentinal sensitivity at the 3 stages, nonparametric Friedman and Wilcoxon tests were performed. The level of significance used was 5%. These analyses were performed with Statistica software (version 6.0, Statistica for Windows, Statsoft, Tulsa, Okla).

Results

The error study showed that only variables SN.GoGn, G’Prn’Pog’ and LL-E had systematic errors, and casual errors varied from zero (S-Go/LAFH) to 1.28° (Md1.NB).

Although treatment changes were also included, the emphasis in this evaluation was on the posttreatment changes. Therefore, the results demonstrated that some changes after the occlusal adjustment, such as decreased lower anterior face height (LAFH) and the increased overbite had significant relapses at the long-term posttreatment stage, although not with values similar to the initial stage. Only FMA and posterior molar height (PMH) relapsed significantly toward similar initial values in the long term ( Table I ).

Table I

Means and standards deviations of cephalometric variables before and after occlusal adjustment (OA) and in the long term (n = 17) and results of dependent ANOVA and Tukey tests

	Before OA	After OA	Long term
Variable	Mean (SD)	Mean (SD)	Mean (SD)	P
Mandibular components
P-NB (mm)	1.16 (1.52) ^A	1.55 (1.59) ^B	1.27 (1.42) ^AB	0.035 ^∗
P-Nperp (mm)	−8.46 (9.71) ^A	−7.44 (9.85) ^A	−8.53 (10.15) ^A	0.055
SNB (°)	78.35 (4.64) ^A	78.64 (4.40) ^A	78.61 (4.43) ^A	0.513
Maxillomandibular relationships
Wits (mm)	−0.77 (1.70) ^A	−0.63 (2.08) ^A	−1.02 (2.25) ^A	0.516
ANB (°)	4.36 (2.45) ^A	3.95 (2.33) ^AB	3.77 (2.32) ^B	0.012 ^∗
NAP (°)	7.41 (5.78) ^A	6.38 (5.50) ^B	6.25 (5.39) ^B	0.006 ^∗
Facial patterns
FMA (°)	33.08 (7.84) ^A	32.15 (7.63)B	32.91 (7.79) ^A	0.000 ^∗
SN.GoGn (°)	37.94 (8.35) ^A	36.97 (8.30) ^B	36.91 (8.01) ^B	0.001 ^∗
NSGn (°)	70.41 (4.86) ^A	69.65 (4.74) ^B	69.69 (4.45) ^B	0.010 ^∗
Vertical components
S-Go (mm)	74.81 (6.70) ^A	74.72 (7.02) ^A	75.17 (6.86) ^A	0.342
PMH (mm)	54.59 (4.57) ^A	53.25 (4.41) ^B	54.36 (4.29) ^A	0.000 ^∗
LAFH (mm)	74.41 (5.40) ^A	72.25 (4.73) ^B	73.74 (4.89) ^C	0.000 ^∗
S-Go/LAFH	1.01 (0.12) ^A	1.03 (0.12) ^B	1.02 (0.12) ^B	0.000 ^∗
Dentoalveolar components
Overjet (mm)	2.77 (1.31) ^A	2.68 (0.82) ^A	3.09 (1.34) ^A	0.091
Overbite (mm)	−1.11 (0.85) ^A	1.17 (0.89) ^B	0.41 (0.77) ^C	0.000 ^∗
Md1-AP (mm)	5.10 (1.81) ^A	4.97 (1.81) ^A	5.14 (1.84) ^A	0.504
Md1.NB (°)	32.38 (6.61) ^A	31.62 (6.29) ^A	33.12 (5.12) ^A	0.083
Md1-NB (mm)	8.10 (2.25) ^A	7.95 (2.38) ^A	7.86 (2.37) ^A	0.221
Soft-tissue components
G’Prn’Pog’ (°)	137.96 (5.08) ^A	139.24 (4.63) ^B	139.75 (4.94) ^B	0.000 ^∗
G’Sn’Pog’ (°)	162.98 (6.57) ^A	164.10 (6.60) ^B	163.96 (7.61) ^B	0.041 ^∗
Sn-Me’ (mm)	73.57 (4.51) ^A	73.15 (4.55) ^A	73.20 (4.05) ^A	0.502
Interlabial gap (mm)	2.78 (3.01) ^A	1.34 (2.02) ^B	1.10 (1.12) ^B	0.014 ^∗
LL-E (mm)	0.60 (1.92) ^A	0.07 (2.20) ^AB	−0.34 (2.93) ^B	0.039 ^∗
LL-Sn’Pog’ (mm)	4.87 (1.60) ^A	4.47 (2.00) ^AB	3.95 (2.46) ^B	0.046 ^∗

Different letters indicate statistically significant differences.

∗ Statistically significant at P <0.05.

Patients whose occlusal adjustment was performed before age 21 years had similar results to the whole sample, except that LAFH relapsed toward similar initial values ( Table II ).

Table II

Means and standards deviations of cephalometric variables before and after occlusal adjustment (OA) and in the long term for patients under 21 years of age after OA (n = 9) and results of dependent ANOVA and Tukey tests

	Before OA	After OA	Long term
Variable	Mean (SD)	Mean (SD)	Mean (SD)	P
Mandibular components
P-NB (mm)	0.96 (1.65) ^A	1.43 (1.53) ^A	1.27 (1.44) ^A	0.088
P-Nperp (mm)	−7.24 (10.92) ^A	−6.12 (11.21) ^A	−6.93 (11.42) ^A	0.236
SNB (°)	77.58 (4.61) ^A	77.75 (4.39) ^A	77.85 (4.53) ^A	0.724
Maxillomandibular relationships
Wits (mm)	−0.58 (1.95) ^A	0.00 (2.48) ^A	0.06 (2.48) ^A	0.174
ANB (°)	5.55 (2.42) ^A	5.14 (2.32) ^A	5.05 (1.89) ^A	0.133
NAP (°)	9.84 (5.83) ^A	8.85 (5.63) ^A	8.73 (4.72) ^A	0.075
Facial patterns
FMA (°)	33.91 (9.83) ^A	32.84 (9.85) ^B	33.67 (9.92) ^A	0.007 ^∗
SN.GoGn (°)	40.36 (9.66) ^A	39.48 (9.62) ^AB	39.35 (9.49) ^B	0.032 ^∗
NSGn (°)	71.21 (4.89) ^A	70.51 (4.60) ^B	70.52 (4.41) ^B	0.022 ^∗
Vertical components
S-Go (mm)	71.80 (7.31) ^A	71.78 (8.09) ^A	72.42 (7.89) ^A	0.288
PMH (mm)	52.96 (4.29) ^A	51.59 (4.31) ^B	52.80 (3.85) ^A	0.000 ^∗
LAFH (mm)	73.69 (4.46) ^A	71.42 (3.79) ^B	73.23 (3.78) ^A	0.000 ^∗
S-Go/LAFH	0.97 (0.14) ^A	1.00 (0.14) ^B	0.99 (0.14) ^AB	0.032 ^∗
Dentoalveolar components
Overjet (mm)	2.91 (1.20) ^A	2.73 (0.90) ^A	3.22 (1.43) ^A	0.184
Overbite (mm)	−1.01 (0.52) ^A	1.43 (0.97) ^B	0.48 (0.93) ^C	0.000 ^∗
Md1-AP (mm)	4.74 (2.06) ^A	4.66 (2.07) ^A	4.93 (2.22) ^A	0.365
Md1.NB (°)	32.22 (6.75) ^A	31.91 (6.28) ^A	32.82 (4.64) ^A	0.575
Md1-NB (mm)	8.36 (2.70) ^A	8.37 (2.80) ^A	8.51 (2.83) ^A	0.529
Soft-tissue components
G’Prn’Pog’ (°)	137.33 (6.00) ^A	138.56 (5.12) ^AB	139.05 (5.58) ^B	0.042 ^∗
G’Sn’Pog’ (°)	160.94 (6.66) ^A	162.17 (6.86) ^A	161.81 (8.16) ^A	0.310
Sn-Me’ (mm)	73.45 (2.44) ^A	73.11 (2.66) ^A	73.01 (3.22) ^A	0.525
Interlabial gap (mm)	3.43 (3.72) ^A	1.28 (2.09) ^A	1.38 (1.50) ^A	0.060
LL-E (mm)	1.24 (2.44) ^A	0.53 (2.85) ^A	0.55 (3.63) ^A	0.356
LL-Sn’Pog’ (mm)	4.95 (1.93) ^A	4.44 (2.69) ^A	4.33 (3.30) ^A	0.525

Different letters indicate statistically significant differences.

∗ Statistically significant at P <0.05.

Patients whose occlusal adjustment was performed after 21 years of age had significant relapses of PMH and LAFH toward similar values of the initial stage ( Table III ).

Table III

Means and standards deviations of cephalometric variables before and after occlusal adjustment (OA) and in the long term for patients over 21 years of age at the OA (n = 8) and results of dependent ANOVA and Tukey tests

	Before OA	After OA	Long term
Variable	Mean (SD)	Mean (SD)	Mean (SD)	P
Mandibular components
P-NB (mm)	1.38 (1.44) ^A	1.68 (1.75) ^A	1.27 (1.50) ^A	0.178
P-Nperp (mm)	−9.83 (8.67) ^A	−8.92 (8.55) ^A	−10.33 (8.91) ^A	0.203
SNB (°)	79.22 (4.83) ^A	79.65 (4.47) ^A	79.46 (4.45) ^A	0.654
Maxillomandibular relationships
Wits (mm)	−0.97 (1.49) ^A	−1.35 (1.32) ^A	−2.26 (1.11) ^A	0.065
ANB (°)	3.02 (1.78) ^A	2.62 (1.56) ^A	2.33 (1.93) ^A	0.112
NAP (°)	4.67 (4.63) ^A	3.61 (4.03) ^A	3.46 (4.90) ^A	0.118
Facial patterns
FMA (°)	32.16 (5.32) ^A	31.37 (4.56) ^A	32.06 (4.97) ^A	0.087
SN.GoGn (°)	35.21 (6.06) ^A	34.15 (5.87) ^A	34.17 (5.24) ^A	0.062
NSGn (°)	69.51 (5.00) ^A	68.70 (5.03) ^A	68.76 (4.61) ^A	0.223
Vertical components
S-Go (mm)	78.20 (4.10) ^A	78.02 (3.79) ^A	78.27 (3.94) ^A	0.874
PMH (mm)	56.42 (4.41) ^A	55.12 (3.95) ^B	56.12 (4.30) ^A	0.002 ^∗
LAFH (mm)	75.22 (6.52) ^A	73.19 (5.74) ^B	74.31 (6.13) ^A	0.000 ^∗
S-Go/LAFH	1.04 (0.11) ^A	1.06 (0.10) ^B	1.06 (0.10) ^AB	0.007 ^∗
Dentoalveolar components
Overjet (mm)	2.61 (1.49) ^A	2.63 (0.77) ^A	2.95 (1.31) ^A	0.465
Overbite (mm)	−1.23 (1.15) ^A	0.88 (0.74) ^B	0.32 (0.60) ^B	0.000 ^∗
Md1-AP (mm)	5.51 (1.50) ^A	5.32 (1.53) ^A	5.38 (1.42) ^A	0.747
Md1.NB (°)	32.57 (6.90) ^A	31.30 (6.72) ^A	33.47 (5.92) ^A	0.131
Md1-NB (mm)	7.80 (1.76) ^A	7.48 (1.87) ^AB	7.13 (1.59) ^B	0.012 ^∗
Soft-tissue components
G’Prn’Pog’ (°)	138.67 (4.11) ^A	140.00 (4.22) ^AB	140.55 (4.34) ^B	0.010 ^∗
G’Sn’Pog’ (°)	165.27 (6.05) ^A	166.27 (5.96) ^A	166.38 (6.60) ^A	0.051
Sn-Me’ (mm)	73.70 (6.29) ^A	73.21 (6.26) ^A	73.42 (5.06) ^A	0.786
Interlabial gap (mm)	2.06 (1.93) ^A	1.40 (2.09) ^A	0.78 (0.26) ^A	0.211
LL-E (mm)	−0.11 (0.70) ^A	−0.43 (1.10) ^AB	−1.36 (1.51) ^B	0.038 ^∗
LL-Sn’Pog’ (mm)	4.78 (1.26) ^A	4.50 (0.93) ^AB	3.53 (0.99) ^B	0.017 ^∗

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Tags: American Journal of Orthodontics and Dentofacial Orthopedics Volume 138 Issue 1

Apr 14, 2017 | Posted by drzezo in Orthodontics | Comments Off

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Stability of anterior open-bite treatment with occlusal adjustment

Introduction

Methods

Results

Conclusions

Material and methods

Statistical analysis

Results

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Pocket Dentistry

Fastest Clinical Dentistry Insight Engine

Stability of anterior open-bite treatment with occlusal adjustment

Introduction

Methods

Results

Conclusions

Material and methods

Statistical analysis

Results

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