Accepted Manuscript Effect of premolar extraction and presence of the lower third molar on lower second molar angulation in orthodontic treatment Tae min You , DDS, PhD Bo Hyun Ban , DDS Jin-Sun Jeong , DH Jisun Huh , DDS, MSD Re-Mee Doh , DDS, PhD Wonse Park , DDS, PhD PII:
S2212-4403(14)00467-2
DOI:
10.1016/j.oooo.2014.05.002
Reference:
OOOO 916
To appear in:
Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Received Date: 4 February 2014 Revised Date:
22 April 2014
Accepted Date: 5 May 2014
Please cite this article as: You Tm, Ban BH, Jeong J-S, Huh J, Doh R-M, Park W, Effect of premolar extraction and presence of the lower third molar on lower second molar angulation in orthodontic treatment, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology (2014), doi: 10.1016/ j.oooo.2014.05.002. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Effect of premolar extraction and presence of the lower third molar on lower second molar angulation in orthodontic treatment
RI PT
Tae min You, DDS, PhD1, Bo Hyun Ban, DDS2, Jin-Sun Jeong, DH3, Jisun Huh, DDS, MSD3, Re-Mee Doh, DDS, PhD4, Wonse Park, DDS, PhD5
1
Assistant Professor, Department of Advanced General Dentistry, Dental Hospital, Dankook
Resident, Department of Advanced General Dentistry, Dental Hospital, Yonsei University, Seoul,
M AN U
2
SC
University, Cheonan, Korea
Korea 3
Researcher, Department of Advanced General Dentistry, Dental Hospital, Yonsei University, Seoul,
Korea 4
Clinical Assistant Professor, Department of Advanced General Dentistry, Dental Hospital, Dankook
5
TE D
University, Cheonan, Korea
Associate Professor, Department of Advanced General Dentistry, Dental Hospital, Yonsei University,
EP
Seoul, Korea
AC C
Address correspondence and reprint requests to: Professor Wonse Park,
Department of Advanced General Dentistry, College of Dentistry, Yonsei University, Yonseiro 50, Seodaemun-gu, Seoul 120-752, Korea E-mail: [email protected] Tel.: +82-2-2228-8980, Fax: +82-2-2227-8906
1
ACCEPTED MANUSCRIPT Acknowledgement We have no conflicts of interest in this study; This work was supported by the research fund from Yonsei University College of Dentistry for 2012 (2-2-12-0020)
RI PT
Word Count for Abstract: 141 Complete Manuscript Word Count: 2323 Number of References: 42
AC C
EP
TE D
M AN U
SC
Number of Figures/Tables: 5 / 2
2
ACCEPTED MANUSCRIPT ABSTRACT Objectives: To evaluate the change in mandibular second-molar angulation (M2) in orthodontic treatment with premolar extraction and lower third molar (M3). Study Design: Panoramic radiographs were evaluated in 3 groups of 129 subjects: (1) control, no orthodontic treatment (n=65),
RI PT
(2) extraction, orthodontic treatment with premolar extraction (n=30), and (3) nonextraction, orthodontic treatment without premolar extraction (n=34). The angular difference and ratio of M2 to the first molar (M1), the change in the angulation of M2 between pre- and postorthodontic treatment,
SC
a distal bone level of M2. Results: Angular difference and ratio of M2 to M1, Angulation change of M2 between pre- and postorthodontic treatment, distal bone level of M2 were higher in the
M AN U
nonextraction group than in the control and extraction groups. Conclusion: The successful orthodontic alignment of the M2 might not be achieved in non-extraction cases when the M3s are
TE D
present.
Keywords: mandibular second molar, angulation, nonextraction orthodontic treatment, preorthodontic
Clinical Relevance
EP
extraction, third molar
AC C
The successful orthodontic alignment of the lower second molar might not be achieved in nonextraction cases when the lower third molars are present. This might be an indication of preorthodontic lower third molar extraction.
3
ACCEPTED MANUSCRIPT Introduction There are two orthodontic methods for the treatment of arch alignment, which may or may not involve extraction of the premolars. If crowding is severe and there is insufficient arch length available,
RI PT
premolar extraction is the preferred method. However, if there is sufficient arch length or the protrusion of the lip is not severe, the orthodontist may choose the nonextraction method. With extraction of the premolars, an anchor loss occurs due to the forward movement of the molar, and a space may develop for eruption of the third molar(M3); however, in the nonextraction method, which
SC
involves holding back (arch length preservation) or distalization of the permanent molars, the second molar (M2) may move backward, tilt distally, or rotate, so that the area available for M3 eruption may
M AN U
be more restricted.1-8 (figure 1,2)
In 1972, Andrews stated in his six keys to normal occlusion that a slight mesial angulation of the crown was in fact normal occlusion.9 Cuoghi et al. compared the mesiodistal axial angulations of the mandibular premolars and molars with or without the presence of the M3 and found that the M2 had a
TE D
slight mesial angulation or was parallel relative to the M1, irrespective of the presence of the M3.10 However, in the Orthodontic treatment without premolar extractions which involves the holding back (arch length preservation) or distalization of M2, the presence or impaction of the lower third molar
EP
may affect of the angulation of the M2s. In contrast, the lack of mesial movement of the first and second molars and the ‘‘driving’’ of the M2 distally, leads to posterior space deficiencies for the M3 in
AC C
adolescent orthodontic patients. There are many indications for M3 extractions, one of which is the need for orthodontic treatment. There are two theories concerning the influence of M3s on orthodontic treatment. The first is that these teeth are capable of causing interference resulting in the generation of certain irregularities in the positioning of adjacent teeth
11-17
and the second is that they are not.18-23 However, until recently
the removal of M3s to prevent crowding of the lower incisors was not considered warranted according to the data available. Furthermore, early germectomy to prevent impaction or development of crowding was not recommended because the variability in development is too great to allow accurate 4
ACCEPTED MANUSCRIPT prediction.24,25 Although, it is reported in many papers that the presence of M3s is not a direct cause of postorthodontic relapse, some practitioners who believe that the mesial pressure of an erupting M3 is a significant factor for relapse of incisor alignment are likely to recommend early M3 removal before orthodontic treatment.
RI PT
But, there is no study which assessed the usefulness of the prophylactic removal of M3 in orthodontic treatment on the grounds of the M2 angulation and M3 extraction not on the grounds of the orthodontic relapse. So, the aims of this study were to evaluate the change in M2 angulation in
SC
patients treated orthodontically with and without premolar extraction when M3s are present and to ascertain whether there is evidence supporting the prophylactic removal of M3 for adolescent
AC C
EP
TE D
M AN U
orthodontic patients.
5
ACCEPTED MANUSCRIPT Materials and methods This retrospective study was approved by the IRB of Yonsei University Dental Hospital. We selected patients who had been subjected to surgical extraction of the M3s in the Department of Advanced General Dentistry, College of Dentistry, Yonsei University, between January 2009 and December 2010.
RI PT
The reasons for extraction were pain, food impaction, dental caries, periodontal disease, and referral from orthodontists. Patients with missing teeth, facial asymmetry, a history of orthognathic surgery, or presence of a unilateral M3, or where the image quality was too poor for analysis due to a nonerupted
SC
M2 were excluded from the study. Of the 1,747 people originally screened, implementation of the exclusion criteria yielded 129 patients who were eligible and selected for study. Of this sample, we
M AN U
performed random sampling and classified the patients as follows: (1) control group (n=65 patients, 130 sides) who had no orthodontic treatment, (2) the extraction group (n=30 patients, 60 sides) who had orthodontic treatment with premolar extraction, and (3) the nonextraction group (n=34 patients, 68 sides) who had orthodontic treatment without premolar extraction.
TE D
Measurements
We evaluated the panoramic radiographs of all of our subjects. One observer evaluated each of the radiographs using the Dental Picture Archiving and Communication System twice, with an interval of
EP
1 week. A midline bisector was drawn at the level of the nasal septum and the anterior nasal spine. A perpendicular line was drawn on this midline bisector that expanded through the palatal shadow
AC C
bilaterally. This constructed plane was termed the horizontal reference plane. The outlines of the mandibular first molars (M1s) and M2s, and their long axes were drawn. The long axes of the M1s and M2s were traced from the midocclusal point through the midpoint of the root bifurcation and the midpoint between the mesial and distal root tips. The M1 and M2 angulations were defined as the outer angles formed by their long axes with the horizontal reference plane. The relative angle ratio of the M2 long axis to the M1 long axis (M2/M1) was calculated to minimize potential errors such as those caused by magnification and distortion of the panoramic radiograph.(Figure 3). In addition, the
6
ACCEPTED MANUSCRIPT distal bone level of the M2s was evaluated on panoramic radiographs and classified into three types, 1–3, as shown in Figure 4. Statistical analysis was performed to check the significance of differences in data between the groups.
RI PT
Results
The average angle difference (M2–M1) and the angle ratio (M2/M1) of the M2s and M1s were significantly higher in the nonextraction group than in the extraction and control groups (one-way
SC
ANOVA and Pearson chi-square test, p-value
S2212-4403(14)00467-2
DOI:
10.1016/j.oooo.2014.05.002
Reference:
OOOO 916
To appear in:
Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Received Date: 4 February 2014 Revised Date:
22 April 2014
Accepted Date: 5 May 2014
Please cite this article as: You Tm, Ban BH, Jeong J-S, Huh J, Doh R-M, Park W, Effect of premolar extraction and presence of the lower third molar on lower second molar angulation in orthodontic treatment, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology (2014), doi: 10.1016/ j.oooo.2014.05.002. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Effect of premolar extraction and presence of the lower third molar on lower second molar angulation in orthodontic treatment
RI PT
Tae min You, DDS, PhD1, Bo Hyun Ban, DDS2, Jin-Sun Jeong, DH3, Jisun Huh, DDS, MSD3, Re-Mee Doh, DDS, PhD4, Wonse Park, DDS, PhD5
1
Assistant Professor, Department of Advanced General Dentistry, Dental Hospital, Dankook
Resident, Department of Advanced General Dentistry, Dental Hospital, Yonsei University, Seoul,
M AN U
2
SC
University, Cheonan, Korea
Korea 3
Researcher, Department of Advanced General Dentistry, Dental Hospital, Yonsei University, Seoul,
Korea 4
Clinical Assistant Professor, Department of Advanced General Dentistry, Dental Hospital, Dankook
5
TE D
University, Cheonan, Korea
Associate Professor, Department of Advanced General Dentistry, Dental Hospital, Yonsei University,
EP
Seoul, Korea
AC C
Address correspondence and reprint requests to: Professor Wonse Park,
Department of Advanced General Dentistry, College of Dentistry, Yonsei University, Yonseiro 50, Seodaemun-gu, Seoul 120-752, Korea E-mail: [email protected] Tel.: +82-2-2228-8980, Fax: +82-2-2227-8906
1
ACCEPTED MANUSCRIPT Acknowledgement We have no conflicts of interest in this study; This work was supported by the research fund from Yonsei University College of Dentistry for 2012 (2-2-12-0020)
RI PT
Word Count for Abstract: 141 Complete Manuscript Word Count: 2323 Number of References: 42
AC C
EP
TE D
M AN U
SC
Number of Figures/Tables: 5 / 2
2
ACCEPTED MANUSCRIPT ABSTRACT Objectives: To evaluate the change in mandibular second-molar angulation (M2) in orthodontic treatment with premolar extraction and lower third molar (M3). Study Design: Panoramic radiographs were evaluated in 3 groups of 129 subjects: (1) control, no orthodontic treatment (n=65),
RI PT
(2) extraction, orthodontic treatment with premolar extraction (n=30), and (3) nonextraction, orthodontic treatment without premolar extraction (n=34). The angular difference and ratio of M2 to the first molar (M1), the change in the angulation of M2 between pre- and postorthodontic treatment,
SC
a distal bone level of M2. Results: Angular difference and ratio of M2 to M1, Angulation change of M2 between pre- and postorthodontic treatment, distal bone level of M2 were higher in the
M AN U
nonextraction group than in the control and extraction groups. Conclusion: The successful orthodontic alignment of the M2 might not be achieved in non-extraction cases when the M3s are
TE D
present.
Keywords: mandibular second molar, angulation, nonextraction orthodontic treatment, preorthodontic
Clinical Relevance
EP
extraction, third molar
AC C
The successful orthodontic alignment of the lower second molar might not be achieved in nonextraction cases when the lower third molars are present. This might be an indication of preorthodontic lower third molar extraction.
3
ACCEPTED MANUSCRIPT Introduction There are two orthodontic methods for the treatment of arch alignment, which may or may not involve extraction of the premolars. If crowding is severe and there is insufficient arch length available,
RI PT
premolar extraction is the preferred method. However, if there is sufficient arch length or the protrusion of the lip is not severe, the orthodontist may choose the nonextraction method. With extraction of the premolars, an anchor loss occurs due to the forward movement of the molar, and a space may develop for eruption of the third molar(M3); however, in the nonextraction method, which
SC
involves holding back (arch length preservation) or distalization of the permanent molars, the second molar (M2) may move backward, tilt distally, or rotate, so that the area available for M3 eruption may
M AN U
be more restricted.1-8 (figure 1,2)
In 1972, Andrews stated in his six keys to normal occlusion that a slight mesial angulation of the crown was in fact normal occlusion.9 Cuoghi et al. compared the mesiodistal axial angulations of the mandibular premolars and molars with or without the presence of the M3 and found that the M2 had a
TE D
slight mesial angulation or was parallel relative to the M1, irrespective of the presence of the M3.10 However, in the Orthodontic treatment without premolar extractions which involves the holding back (arch length preservation) or distalization of M2, the presence or impaction of the lower third molar
EP
may affect of the angulation of the M2s. In contrast, the lack of mesial movement of the first and second molars and the ‘‘driving’’ of the M2 distally, leads to posterior space deficiencies for the M3 in
AC C
adolescent orthodontic patients. There are many indications for M3 extractions, one of which is the need for orthodontic treatment. There are two theories concerning the influence of M3s on orthodontic treatment. The first is that these teeth are capable of causing interference resulting in the generation of certain irregularities in the positioning of adjacent teeth
11-17
and the second is that they are not.18-23 However, until recently
the removal of M3s to prevent crowding of the lower incisors was not considered warranted according to the data available. Furthermore, early germectomy to prevent impaction or development of crowding was not recommended because the variability in development is too great to allow accurate 4
ACCEPTED MANUSCRIPT prediction.24,25 Although, it is reported in many papers that the presence of M3s is not a direct cause of postorthodontic relapse, some practitioners who believe that the mesial pressure of an erupting M3 is a significant factor for relapse of incisor alignment are likely to recommend early M3 removal before orthodontic treatment.
RI PT
But, there is no study which assessed the usefulness of the prophylactic removal of M3 in orthodontic treatment on the grounds of the M2 angulation and M3 extraction not on the grounds of the orthodontic relapse. So, the aims of this study were to evaluate the change in M2 angulation in
SC
patients treated orthodontically with and without premolar extraction when M3s are present and to ascertain whether there is evidence supporting the prophylactic removal of M3 for adolescent
AC C
EP
TE D
M AN U
orthodontic patients.
5
ACCEPTED MANUSCRIPT Materials and methods This retrospective study was approved by the IRB of Yonsei University Dental Hospital. We selected patients who had been subjected to surgical extraction of the M3s in the Department of Advanced General Dentistry, College of Dentistry, Yonsei University, between January 2009 and December 2010.
RI PT
The reasons for extraction were pain, food impaction, dental caries, periodontal disease, and referral from orthodontists. Patients with missing teeth, facial asymmetry, a history of orthognathic surgery, or presence of a unilateral M3, or where the image quality was too poor for analysis due to a nonerupted
SC
M2 were excluded from the study. Of the 1,747 people originally screened, implementation of the exclusion criteria yielded 129 patients who were eligible and selected for study. Of this sample, we
M AN U
performed random sampling and classified the patients as follows: (1) control group (n=65 patients, 130 sides) who had no orthodontic treatment, (2) the extraction group (n=30 patients, 60 sides) who had orthodontic treatment with premolar extraction, and (3) the nonextraction group (n=34 patients, 68 sides) who had orthodontic treatment without premolar extraction.
TE D
Measurements
We evaluated the panoramic radiographs of all of our subjects. One observer evaluated each of the radiographs using the Dental Picture Archiving and Communication System twice, with an interval of
EP
1 week. A midline bisector was drawn at the level of the nasal septum and the anterior nasal spine. A perpendicular line was drawn on this midline bisector that expanded through the palatal shadow
AC C
bilaterally. This constructed plane was termed the horizontal reference plane. The outlines of the mandibular first molars (M1s) and M2s, and their long axes were drawn. The long axes of the M1s and M2s were traced from the midocclusal point through the midpoint of the root bifurcation and the midpoint between the mesial and distal root tips. The M1 and M2 angulations were defined as the outer angles formed by their long axes with the horizontal reference plane. The relative angle ratio of the M2 long axis to the M1 long axis (M2/M1) was calculated to minimize potential errors such as those caused by magnification and distortion of the panoramic radiograph.(Figure 3). In addition, the
6
ACCEPTED MANUSCRIPT distal bone level of the M2s was evaluated on panoramic radiographs and classified into three types, 1–3, as shown in Figure 4. Statistical analysis was performed to check the significance of differences in data between the groups.
RI PT
Results
The average angle difference (M2–M1) and the angle ratio (M2/M1) of the M2s and M1s were significantly higher in the nonextraction group than in the extraction and control groups (one-way
SC
ANOVA and Pearson chi-square test, p-value
