ORIGINAL ARTICLE
Comparison of Treatment Duration Between Conventional Three-Stage Method and Surgery-First Approach in Patients With Skeletal Class III Malocclusion Byung-kyu Min, BA,* Jin-Young Choi, DDS, MD,† and Seung-Hak Baek, DDS, MSD‡
atients with skeletal Class III malocclusion have been treated using the conventional 3-stage method, which consisted of preoperative orthodontic treatment (Pre-OP-OT), orthognathic surgery, and postoperative orthodontic treatment (Post-OP-OT).1 Patient’s appearance would deteriorate and inconveniences could occur during
preoperative orthodontic treatment in the conventional 3-stage method.2–6 However, this method has definite advantages including establishment of dental decompensation and arch coordination before orthognathic surgery via preoperative orthodontic treatment.2–9 The surgery-first approach concept (SFA) was introduced.2,3 Sometimes, minimal Pre-OP-OT shorter than 3 to 4 months can be employed to solve issues such as crowding, angulation, tipping, rotation, premature contact, and arch width discrepancy.4 This technique has several advantages including (1) improvement of the chief complaint (aesthetic concerns) in the early stage of treatment, (2) a decrease in the total treatment (TT) duration by omitting or minimizing the extent of Pre-OP-OT, and (3) a decrease in the degree of difficulty and increase in tooth movement speed by the regional acceleratory phenomenon during the Post-OP-OT phase.4–6,10–12 However, it also has disadvantages such as (1) difficulty in precisely predicting the surgical results, and (2) simultaneous dental decompensation, arch coordination, and occlusal settling during Post-OP-OT.4,6 The SFA can be used to successfully treat the patients with non-extraction approach, well-aligned or mildly crowded anterior teeth, mild to moderate curve of Spee/vertical problem, little or no transverse discrepancy, and normal to mildly proclined/retroclined incisor inclination.4,5 Numerous previous studies have been performed to assess the treatment durations in the conventional 3-stage method,7,13–16 and to compare the treatment duration between university hospital and local clinics.17,18 However, most of these studies did not specify the type of malocclusion, kinds of surgery used, and whether or not extraction was performed. Few studies have compared the durations of TT, Pre-OP-OT, and Post-OP-OT between the conventional 3-stage method and the SFA in patients with skeletal Class III malocclusion.12 Therefore, the purposes of this retrospective study were to compare the durations of TT, Pre-OP-OT, and Post-OP-OT between the conventional three-stage method (group 1) and the SFA (group 2; including patients with Pre-OP-OT shorter than 100 days) and to evaluate the correlation between Pre-OP-OT and Post-OP-OT durations in group 1. Null hypotheses were as follows: (1) there was no difference in TT, PreOP-OT, and Post-OP-OT durations between groups 1 and 2; and (2) there was no correlation between Pre-OP-OT and Post-OP-OT durations in group 1.
From the *School of Dentistry, Seoul National University, Seoul; and †Departments of Oral and Maxillofacial Surgery and ‡Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, South Korea. Received December 29, 2013. Accepted for publication April 7, 2014. Address correspondence and reprint requests to Dr Seung-Hak Baek, DDS, MSD, PhD, Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Yeonkun-dong #28, Jongro-ku, Seoul 110-768, South Korea; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001002
The subjects consisted of 44 adult patients with skeletal Class III malocclusion who were treated with non-extraction and 2-jaw surgery (1-piece LeFort I osteotomy and bilateral sagittal split ramus osteotomy) at Seoul National University Dental Hospital (SNUDH). All patients had lateral cephalograms taken at the initial visit (T0), 1 month before surgery (T1), immediately after surgery (T2), and at debonding (T3). Patients who had a craniofacial deformity, cleft lip and palate, or degenerative joint disorder were excluded. This study was reviewed and approved by the Institutional Review Board of Seoul National University Dental Hospital (IRB number CRI 13018).
Abstract: The purpose of this retrospective study was to compare the durations of total treatment (TT), and preoperative orthodontic treatment (Pre-OP-OT) and postoperative orthodontic treatment (PostOP-OT) between conventional 3-stage method (CTM) and surgeryfirst approach (SFA). The subjects consisted of skeletal Class III patients who were treated with non-extraction and 2-jaw surgery and had lateral cephalograms taken at initial visit (T0), 1 month before surgery (T1), immediately after surgery (T2), and at debonding (T3). They were allocated into group 1 (CTM, n = 26) and group 2 (SFA, n = 18, including the subjects with Pre-OP-OT shorter than 100 days). Statistical analysis was performed after measuring skeletodental variables in the T0 lateral cephalogram, the amount of surgical change (ΔT2-T1), and the durations of TT, Pre-OP-OT, and Post-OP-OT. There were no significant differences in skeletodental variables at the T0 stage or in ΔT2-T1 between groups 1 and 2. Therefore, differences in durations of TT and Post-OP-OT between groups 1 and 2 could be attributed to the difference in treatment methods (CTM vs. SFA). TT and PreOP-OT were significantly longer in group 1 than those in group 2 (324.2 days and 385.7 days, respectively; all P < 0.001). Although Post-OP-OT was longer in group 2 than in group 1, the difference was not significant (63.3 days; P > 0.05). In group 1, the negative correlation between durations of Pre-OP-OT and Post-OP-OT was not verified, which means that Post-OP-OT was not shortened despite longer Pre-OP-OT. The results from this study can be used as a guideline in diagnosis and treatment planning for SFA. Key Words: Treatment duration, skeletal Class III patients, conventional 3-stage method, surgery-first approach (J Craniofac Surg 2014;25: 1752–1756)
P
1752
PATIENTS AND METHODS
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
FIGURE 1. Landmarks and reference planes: S, sella; N, nasion; Or, orbitale; Po, porion; A, point A; B, point B; Pog, pogonion; Me, menton; Go, gonion; U1E, the incisal edge of the maxillary central incisor; UIA, the root apex of the maxillary central incisor; LIE, the incisal edge of the mandibular central incisor (LI); LIA, the root apex of the mandibular central incisor; U6MBC, the mesiobuccal cusp tip (MBC) of the maxillary first molar; L6MBC, the MBC of the mandibular first molar; Horizontal reference plane (HRP), a horizontal plane angulated 7 degrees clockwise to the SN line passing through the Sella; Vertical reference plane (VRP), a perpendicular line to the HRP passing through the sella.
Patients were allocated into group 1 (conventional 3-stage method; n = 26, 11 males and 15 females; mean age, 21.16 ± 2.77 years; including subjects with Pre-OP-OT longer than 100 days) and group 2 (SFA; n = 18, 7 males and 11 females; mean age, 23.86 ± 5.63 years; including subjects with Pre-OP-OT shorter than 100 days). The definitions of landmarks and reference lines, cephalometric variables, and surgical movement of the maxilla and mandible are described in Figs. 1–3. After measuring skeletodental variables in the T0 lateral cephalogram, the amount of surgical change (ΔT2-T1), and the durations of TT (T0-T3), Pre-OP-OT (T0-T1), and PostOP-OT (T2-T3), independent t test and correlation analysis were performed. The significance level was set at P less than 0.05.
RESULTS There were no significant differences in skeletodental variables at the T0 stage or in ΔT2-T1 between groups 1 and 2 (Tables 1 and 2). Therefore, differences in the durations of TT and Post-OP-OT between groups 1 and 2 could be attributed to the difference in the treatment methods between the 2 groups (conventional 3-stage method vs. SFA).
Treatment Duration in Surgery-First Approach
FIGURE 3. Surgical movement of the maxilla and mandible. 1. A-V (mm), vertical distance from point A to HRP; 2. PNS-V (mm), vertical distance from PNS to HRP; 3. U6-V (mm), vertical distance from U6MBC to HRP; 4. UI-V (mm), vertical distance from UIE to HRP; 5. A-H (mm), horizontal distance from point A to VRP; 6. PNS-H (mm), horizontal distance from PNS to VRP; 7. U6-H (mm), horizontal distance from U6MBC to VRP; 8. UI-H (mm), horizontal distance from UIE to VRP; 9. B-V (mm), vertical distance from point B to HRP; 10. Pog-V (mm), vertical distance from Pog to HRP; 11. L6-V (mm), vertical distance from L6MBC to HRP; 12. LI-V (mm), vertical distance from LIE to HRP; 13. B-H (mm), horizontal distance from point B to VRP; 14. Pog-H (mm), horizontal distance from Pog to VRP; 15. L6-H (mm), horizontal distance from L6MBC to VRP; 16. LI-H (mm), horizontal distance from LIE to VRP.
TT and Pre-OP-OT were significantly longer in group 1 than in group 2 (324.2 days and 385.7 days, respectively; all P < 0.001, Table 3). Because dental decompensation, arch coordination, and occlusal settling were performed simultaneously during the Post-OP-OT period in group 2, the duration of Post-OP-OT in group 2 was predicted to be longer than that in group 1. Indeed, Post-OP-OT was longer in group 2 than in group 1, but the difference was not statistically significant (63.3 days; P > 0.05, Table 3). The duration of TT in group 1 was greatly affected by the duration of Pre-OP-OT and Post-OP-OT (P < 0.001 and P < 0.01, respectively; Table 4). However, in group 1, negative correlation between durations of Pre-OP-OT and Post-OP-OT was not verified, which indicates that Post-OP-OT was not shortened despite the longer Pre-OP-OT. The duration of TT in group 2 was considerably affected by the duration of Post-OP-OT (P < 0.001, Table 4). TABLE 1. Demographic Data of the Samples Group 1 (CTM; n = 26; 11 Males and 15 Females)
Group 2 (SFA; n=18; 7 Males and 11 Females)
T0 Stage
Mean
SD
Mean
SD
P
Age (yr)
21.16 81.84 83.57 −1.73 −7.24 36.37 0.51 6.07 108.87 80.11 −1.03 −0.20
2.77 3.92 4.27 3.60 6.65 5.87 3.56 9.42 5.38 9.04 4.11 2.35
23.85 80.01 82.12 −2.11 −9.04 38.12 −0.30 5.37 111.73 83.31 −0.09 0.44
5.63 4.01 4.33 2.75 3.61 6.48 3.34 6.25 7.00 6.05 3.13 1.40
0.0736 0.1396 0.2772 0.7087 0.3028 0.3574 0.4501 0.7850 0.1334 0.1976 0.4178 0.2641
SNA (°) SNB (°), ANB (°) Wits appraisal (mm) SN-GoMe (°) A-N perpendicular (mm) Pog-N perpendicular (mm) U1-SN (°) IMPA (°) Overjet (mm) Overbite (mm) FIGURE 2. Cephalometric variables. 1. SNA (°), 2. SNB (°), 3. ANB (°), 4. Wits appraisal (mm), 5. SN-GoMe (°); 6. A-N perpendicular (mm); 7. Pog-N perpendicular (mm), 8. U1-SN (°); 9. IMPA (°), 10. Overjet (mm); 11. Overbite (mm); U1, long axis of the maxillary central incisor.
Independent t test was performed. SD represents standard deviation; CTM, conventional 3-stage method; SFA, surgery-first approach.
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
1753
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
Min et al
TABLE 2. Comparison of the Amounts of Surgical Movement of the Maxilla and Mandible Group 1 (CTM; n = 26; 11 Males and 15 Females)
Anteroposterior movement (mm)
Maxilla
Mandible
Vertical movement (mm)
Maxilla
Mandible
∆A-H ∆PNS-H ∆U6-H ∆UI-H ∆B-H ∆Pog-H ∆L6-H ∆LI-H ∆A-V ∆PNS-V ∆U6-V ∆UI-V ∆B-V ∆Pog-V ∆L6-V ∆LI-V
Group 2 (SFA; n = 18; 7 Males and 11 Females)
Mean
SD
Mean
SD
P
−0.06 −4.44 2.98 0.33 −3.24 −3.12 1.37 −1.77 −0.45 1.41 −1.31 −1.62 −7.26 −8.60 −3.32 −6.98
2.31 2.48 4.00 2.34 5.58 5.35 6.67 3.15 2.78 3.38 3.70 2.90 5.33 6.26 4.10 4.78
−1.14 −3.12 0.88 −0.29 −3.90 −1.75 3.37 −0.16 −2.26 2.01 −2.03 −0.97 −5.71 −5.58 −4.53 −4.44
3.46 2.15 4.01 3.44 3.62 5.49 6.59 4.12 4.78 4.14 3.89 3.88 7.72 8.89 6.54 5.57
0.2223 0.0731 0.0948 0.4815 0.6624 0.4114 0.3342 0.1478 0.1610 0.5992 0.5411 0.5228 0.4358 0.1930 0.4931 0.1128
Independent t test was performed to compare the variables between the 2 groups. For the anteroposterior movement: (−) indicates setback; (+), advancement. For the vertical movement: (−) indicates superior impaction; (+), elongation.
However, there was no correlation between the durations of minimal Pre-OP-OT and Post-OP-OT (P > 0.05, Table 4).
DISCUSSION Sample Selection In this study, the authors attempted to minimize bias that could affect treatment duration and to objectively evaluate the difference in treatment duration between the 2 groups only by treatment method (conventional 3-stage method vs. SFA). Therefore, the samples were limited to patients who had skeletal Class III malocclusion and were treated with non-extraction and 2-jaw surgery. As a result, it was confirmed that there were no differences in skeletodental variables at the T0 stage or in the amounts of surgical change (ΔT2-T1) between the 2 groups (Tables 1 and 2).
Comparison of the Conventional 3-Stage Method Results Between the Present Study and Previous Studies Because this study evaluated patients treated at a university hospital, it would be prudent to compare the present findings with those of previous studies that used the university hospital samples. The authors identified similar studies conducted by Yang,7 Mavreas and Athanasiou,17 and Slavnic and Marcusson18 (Table 5). In their systemic review, Mavreas and Athanasiou17 reported diverse results in terms of treatment duration because their samples comprised of a mixture of those treated with and without extraction and different surgical methods. Therefore, a comparison of their results with that of the present study did not seem appropriate. Direct comparison between the findings reported by Slavnic and Marcusson,18 Yang7 and this study also could not be drawn because they included patients with Class II and III malocclusion and those with both open bite and cross bite and did not classify their surgical methods. Because this study evaluated the non-extraction cases, it is appropriate to compare our findings with the results from previous studies that obtained from non-extraction cases. Luther et al15,16 reported that Pre-OP-OT and Post-OP-OT took 17 months and
1754
6.5 months, respectively, in the conventional 3-stage method. However, this study exhibited a shorter Pre-OP-OT (10.1 months) and a similar Post-OP-OT (6.8 months) compared to them (Tables 3 and 5).15,16 This finding indirectly suggested that duration of Post-OP-OT might not be related with that of Pre-OP-OT. In addition, the negative correlation between Pre-OP-OT and Post-OP-OT in group 1 was not verified in this study (P > 0.05, Table 4). Therefore, extending Pre-OP-OT too long may not be helpful in terms of decreasing the durations of total treatment and Post-OP-OT. The results from Dowling et al 13 (TT, 21.2 months) and Diaz et al14 (TT, 36 months; Pre-OP-OT, 24 months; Post-OP-OT, 12 months) were difficult to directly compare with those of the present study because they did not provide specifics such as whether or not extraction was performed, the types of malocclusion, surgical methods, etc. (Table 5). When compared with the results of Park et al,6 which were treated with extraction and the conventional 3-stage method, PreOP-OT took 7 months longer for closing space and Post-OP-OT, 1.4 months longer compared to those values for the patients in this study who were treated using non-extraction and the conventional 3-stage method (TT, 25.3 months; Pre-OP-OT, 17.1 months; PostOP-OT, 8.2 months in Park et al; vs. TT 18.1, months; Pre-OP-OT, 10.1 months; Post-OP-OT, 6.8 months in this study; Tables 3 and 5).
TABLE 3. Comparison of Treatment Duration Between Groups 1 and 2 Group 1 (CTM; n = 26; 11 Males and 15 Females)
Group 2 (SFA; n = 18; 7 Males and 11 Females)
Duration
Mean
SD
Mean
SD
P
TT (days)
647.15 416.27 194.35
215.66 185.04 93.22
322.94 30.56 257.61
129.88 29.40 133.08
Comparison of Treatment Duration Between Conventional Three-Stage Method and Surgery-First Approach in Patients With Skeletal Class III Malocclusion Byung-kyu Min, BA,* Jin-Young Choi, DDS, MD,† and Seung-Hak Baek, DDS, MSD‡
atients with skeletal Class III malocclusion have been treated using the conventional 3-stage method, which consisted of preoperative orthodontic treatment (Pre-OP-OT), orthognathic surgery, and postoperative orthodontic treatment (Post-OP-OT).1 Patient’s appearance would deteriorate and inconveniences could occur during
preoperative orthodontic treatment in the conventional 3-stage method.2–6 However, this method has definite advantages including establishment of dental decompensation and arch coordination before orthognathic surgery via preoperative orthodontic treatment.2–9 The surgery-first approach concept (SFA) was introduced.2,3 Sometimes, minimal Pre-OP-OT shorter than 3 to 4 months can be employed to solve issues such as crowding, angulation, tipping, rotation, premature contact, and arch width discrepancy.4 This technique has several advantages including (1) improvement of the chief complaint (aesthetic concerns) in the early stage of treatment, (2) a decrease in the total treatment (TT) duration by omitting or minimizing the extent of Pre-OP-OT, and (3) a decrease in the degree of difficulty and increase in tooth movement speed by the regional acceleratory phenomenon during the Post-OP-OT phase.4–6,10–12 However, it also has disadvantages such as (1) difficulty in precisely predicting the surgical results, and (2) simultaneous dental decompensation, arch coordination, and occlusal settling during Post-OP-OT.4,6 The SFA can be used to successfully treat the patients with non-extraction approach, well-aligned or mildly crowded anterior teeth, mild to moderate curve of Spee/vertical problem, little or no transverse discrepancy, and normal to mildly proclined/retroclined incisor inclination.4,5 Numerous previous studies have been performed to assess the treatment durations in the conventional 3-stage method,7,13–16 and to compare the treatment duration between university hospital and local clinics.17,18 However, most of these studies did not specify the type of malocclusion, kinds of surgery used, and whether or not extraction was performed. Few studies have compared the durations of TT, Pre-OP-OT, and Post-OP-OT between the conventional 3-stage method and the SFA in patients with skeletal Class III malocclusion.12 Therefore, the purposes of this retrospective study were to compare the durations of TT, Pre-OP-OT, and Post-OP-OT between the conventional three-stage method (group 1) and the SFA (group 2; including patients with Pre-OP-OT shorter than 100 days) and to evaluate the correlation between Pre-OP-OT and Post-OP-OT durations in group 1. Null hypotheses were as follows: (1) there was no difference in TT, PreOP-OT, and Post-OP-OT durations between groups 1 and 2; and (2) there was no correlation between Pre-OP-OT and Post-OP-OT durations in group 1.
From the *School of Dentistry, Seoul National University, Seoul; and †Departments of Oral and Maxillofacial Surgery and ‡Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, South Korea. Received December 29, 2013. Accepted for publication April 7, 2014. Address correspondence and reprint requests to Dr Seung-Hak Baek, DDS, MSD, PhD, Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Yeonkun-dong #28, Jongro-ku, Seoul 110-768, South Korea; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001002
The subjects consisted of 44 adult patients with skeletal Class III malocclusion who were treated with non-extraction and 2-jaw surgery (1-piece LeFort I osteotomy and bilateral sagittal split ramus osteotomy) at Seoul National University Dental Hospital (SNUDH). All patients had lateral cephalograms taken at the initial visit (T0), 1 month before surgery (T1), immediately after surgery (T2), and at debonding (T3). Patients who had a craniofacial deformity, cleft lip and palate, or degenerative joint disorder were excluded. This study was reviewed and approved by the Institutional Review Board of Seoul National University Dental Hospital (IRB number CRI 13018).
Abstract: The purpose of this retrospective study was to compare the durations of total treatment (TT), and preoperative orthodontic treatment (Pre-OP-OT) and postoperative orthodontic treatment (PostOP-OT) between conventional 3-stage method (CTM) and surgeryfirst approach (SFA). The subjects consisted of skeletal Class III patients who were treated with non-extraction and 2-jaw surgery and had lateral cephalograms taken at initial visit (T0), 1 month before surgery (T1), immediately after surgery (T2), and at debonding (T3). They were allocated into group 1 (CTM, n = 26) and group 2 (SFA, n = 18, including the subjects with Pre-OP-OT shorter than 100 days). Statistical analysis was performed after measuring skeletodental variables in the T0 lateral cephalogram, the amount of surgical change (ΔT2-T1), and the durations of TT, Pre-OP-OT, and Post-OP-OT. There were no significant differences in skeletodental variables at the T0 stage or in ΔT2-T1 between groups 1 and 2. Therefore, differences in durations of TT and Post-OP-OT between groups 1 and 2 could be attributed to the difference in treatment methods (CTM vs. SFA). TT and PreOP-OT were significantly longer in group 1 than those in group 2 (324.2 days and 385.7 days, respectively; all P < 0.001). Although Post-OP-OT was longer in group 2 than in group 1, the difference was not significant (63.3 days; P > 0.05). In group 1, the negative correlation between durations of Pre-OP-OT and Post-OP-OT was not verified, which means that Post-OP-OT was not shortened despite longer Pre-OP-OT. The results from this study can be used as a guideline in diagnosis and treatment planning for SFA. Key Words: Treatment duration, skeletal Class III patients, conventional 3-stage method, surgery-first approach (J Craniofac Surg 2014;25: 1752–1756)
P
1752
PATIENTS AND METHODS
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
FIGURE 1. Landmarks and reference planes: S, sella; N, nasion; Or, orbitale; Po, porion; A, point A; B, point B; Pog, pogonion; Me, menton; Go, gonion; U1E, the incisal edge of the maxillary central incisor; UIA, the root apex of the maxillary central incisor; LIE, the incisal edge of the mandibular central incisor (LI); LIA, the root apex of the mandibular central incisor; U6MBC, the mesiobuccal cusp tip (MBC) of the maxillary first molar; L6MBC, the MBC of the mandibular first molar; Horizontal reference plane (HRP), a horizontal plane angulated 7 degrees clockwise to the SN line passing through the Sella; Vertical reference plane (VRP), a perpendicular line to the HRP passing through the sella.
Patients were allocated into group 1 (conventional 3-stage method; n = 26, 11 males and 15 females; mean age, 21.16 ± 2.77 years; including subjects with Pre-OP-OT longer than 100 days) and group 2 (SFA; n = 18, 7 males and 11 females; mean age, 23.86 ± 5.63 years; including subjects with Pre-OP-OT shorter than 100 days). The definitions of landmarks and reference lines, cephalometric variables, and surgical movement of the maxilla and mandible are described in Figs. 1–3. After measuring skeletodental variables in the T0 lateral cephalogram, the amount of surgical change (ΔT2-T1), and the durations of TT (T0-T3), Pre-OP-OT (T0-T1), and PostOP-OT (T2-T3), independent t test and correlation analysis were performed. The significance level was set at P less than 0.05.
RESULTS There were no significant differences in skeletodental variables at the T0 stage or in ΔT2-T1 between groups 1 and 2 (Tables 1 and 2). Therefore, differences in the durations of TT and Post-OP-OT between groups 1 and 2 could be attributed to the difference in the treatment methods between the 2 groups (conventional 3-stage method vs. SFA).
Treatment Duration in Surgery-First Approach
FIGURE 3. Surgical movement of the maxilla and mandible. 1. A-V (mm), vertical distance from point A to HRP; 2. PNS-V (mm), vertical distance from PNS to HRP; 3. U6-V (mm), vertical distance from U6MBC to HRP; 4. UI-V (mm), vertical distance from UIE to HRP; 5. A-H (mm), horizontal distance from point A to VRP; 6. PNS-H (mm), horizontal distance from PNS to VRP; 7. U6-H (mm), horizontal distance from U6MBC to VRP; 8. UI-H (mm), horizontal distance from UIE to VRP; 9. B-V (mm), vertical distance from point B to HRP; 10. Pog-V (mm), vertical distance from Pog to HRP; 11. L6-V (mm), vertical distance from L6MBC to HRP; 12. LI-V (mm), vertical distance from LIE to HRP; 13. B-H (mm), horizontal distance from point B to VRP; 14. Pog-H (mm), horizontal distance from Pog to VRP; 15. L6-H (mm), horizontal distance from L6MBC to VRP; 16. LI-H (mm), horizontal distance from LIE to VRP.
TT and Pre-OP-OT were significantly longer in group 1 than in group 2 (324.2 days and 385.7 days, respectively; all P < 0.001, Table 3). Because dental decompensation, arch coordination, and occlusal settling were performed simultaneously during the Post-OP-OT period in group 2, the duration of Post-OP-OT in group 2 was predicted to be longer than that in group 1. Indeed, Post-OP-OT was longer in group 2 than in group 1, but the difference was not statistically significant (63.3 days; P > 0.05, Table 3). The duration of TT in group 1 was greatly affected by the duration of Pre-OP-OT and Post-OP-OT (P < 0.001 and P < 0.01, respectively; Table 4). However, in group 1, negative correlation between durations of Pre-OP-OT and Post-OP-OT was not verified, which indicates that Post-OP-OT was not shortened despite the longer Pre-OP-OT. The duration of TT in group 2 was considerably affected by the duration of Post-OP-OT (P < 0.001, Table 4). TABLE 1. Demographic Data of the Samples Group 1 (CTM; n = 26; 11 Males and 15 Females)
Group 2 (SFA; n=18; 7 Males and 11 Females)
T0 Stage
Mean
SD
Mean
SD
P
Age (yr)
21.16 81.84 83.57 −1.73 −7.24 36.37 0.51 6.07 108.87 80.11 −1.03 −0.20
2.77 3.92 4.27 3.60 6.65 5.87 3.56 9.42 5.38 9.04 4.11 2.35
23.85 80.01 82.12 −2.11 −9.04 38.12 −0.30 5.37 111.73 83.31 −0.09 0.44
5.63 4.01 4.33 2.75 3.61 6.48 3.34 6.25 7.00 6.05 3.13 1.40
0.0736 0.1396 0.2772 0.7087 0.3028 0.3574 0.4501 0.7850 0.1334 0.1976 0.4178 0.2641
SNA (°) SNB (°), ANB (°) Wits appraisal (mm) SN-GoMe (°) A-N perpendicular (mm) Pog-N perpendicular (mm) U1-SN (°) IMPA (°) Overjet (mm) Overbite (mm) FIGURE 2. Cephalometric variables. 1. SNA (°), 2. SNB (°), 3. ANB (°), 4. Wits appraisal (mm), 5. SN-GoMe (°); 6. A-N perpendicular (mm); 7. Pog-N perpendicular (mm), 8. U1-SN (°); 9. IMPA (°), 10. Overjet (mm); 11. Overbite (mm); U1, long axis of the maxillary central incisor.
Independent t test was performed. SD represents standard deviation; CTM, conventional 3-stage method; SFA, surgery-first approach.
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
1753
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
Min et al
TABLE 2. Comparison of the Amounts of Surgical Movement of the Maxilla and Mandible Group 1 (CTM; n = 26; 11 Males and 15 Females)
Anteroposterior movement (mm)
Maxilla
Mandible
Vertical movement (mm)
Maxilla
Mandible
∆A-H ∆PNS-H ∆U6-H ∆UI-H ∆B-H ∆Pog-H ∆L6-H ∆LI-H ∆A-V ∆PNS-V ∆U6-V ∆UI-V ∆B-V ∆Pog-V ∆L6-V ∆LI-V
Group 2 (SFA; n = 18; 7 Males and 11 Females)
Mean
SD
Mean
SD
P
−0.06 −4.44 2.98 0.33 −3.24 −3.12 1.37 −1.77 −0.45 1.41 −1.31 −1.62 −7.26 −8.60 −3.32 −6.98
2.31 2.48 4.00 2.34 5.58 5.35 6.67 3.15 2.78 3.38 3.70 2.90 5.33 6.26 4.10 4.78
−1.14 −3.12 0.88 −0.29 −3.90 −1.75 3.37 −0.16 −2.26 2.01 −2.03 −0.97 −5.71 −5.58 −4.53 −4.44
3.46 2.15 4.01 3.44 3.62 5.49 6.59 4.12 4.78 4.14 3.89 3.88 7.72 8.89 6.54 5.57
0.2223 0.0731 0.0948 0.4815 0.6624 0.4114 0.3342 0.1478 0.1610 0.5992 0.5411 0.5228 0.4358 0.1930 0.4931 0.1128
Independent t test was performed to compare the variables between the 2 groups. For the anteroposterior movement: (−) indicates setback; (+), advancement. For the vertical movement: (−) indicates superior impaction; (+), elongation.
However, there was no correlation between the durations of minimal Pre-OP-OT and Post-OP-OT (P > 0.05, Table 4).
DISCUSSION Sample Selection In this study, the authors attempted to minimize bias that could affect treatment duration and to objectively evaluate the difference in treatment duration between the 2 groups only by treatment method (conventional 3-stage method vs. SFA). Therefore, the samples were limited to patients who had skeletal Class III malocclusion and were treated with non-extraction and 2-jaw surgery. As a result, it was confirmed that there were no differences in skeletodental variables at the T0 stage or in the amounts of surgical change (ΔT2-T1) between the 2 groups (Tables 1 and 2).
Comparison of the Conventional 3-Stage Method Results Between the Present Study and Previous Studies Because this study evaluated patients treated at a university hospital, it would be prudent to compare the present findings with those of previous studies that used the university hospital samples. The authors identified similar studies conducted by Yang,7 Mavreas and Athanasiou,17 and Slavnic and Marcusson18 (Table 5). In their systemic review, Mavreas and Athanasiou17 reported diverse results in terms of treatment duration because their samples comprised of a mixture of those treated with and without extraction and different surgical methods. Therefore, a comparison of their results with that of the present study did not seem appropriate. Direct comparison between the findings reported by Slavnic and Marcusson,18 Yang7 and this study also could not be drawn because they included patients with Class II and III malocclusion and those with both open bite and cross bite and did not classify their surgical methods. Because this study evaluated the non-extraction cases, it is appropriate to compare our findings with the results from previous studies that obtained from non-extraction cases. Luther et al15,16 reported that Pre-OP-OT and Post-OP-OT took 17 months and
1754
6.5 months, respectively, in the conventional 3-stage method. However, this study exhibited a shorter Pre-OP-OT (10.1 months) and a similar Post-OP-OT (6.8 months) compared to them (Tables 3 and 5).15,16 This finding indirectly suggested that duration of Post-OP-OT might not be related with that of Pre-OP-OT. In addition, the negative correlation between Pre-OP-OT and Post-OP-OT in group 1 was not verified in this study (P > 0.05, Table 4). Therefore, extending Pre-OP-OT too long may not be helpful in terms of decreasing the durations of total treatment and Post-OP-OT. The results from Dowling et al 13 (TT, 21.2 months) and Diaz et al14 (TT, 36 months; Pre-OP-OT, 24 months; Post-OP-OT, 12 months) were difficult to directly compare with those of the present study because they did not provide specifics such as whether or not extraction was performed, the types of malocclusion, surgical methods, etc. (Table 5). When compared with the results of Park et al,6 which were treated with extraction and the conventional 3-stage method, PreOP-OT took 7 months longer for closing space and Post-OP-OT, 1.4 months longer compared to those values for the patients in this study who were treated using non-extraction and the conventional 3-stage method (TT, 25.3 months; Pre-OP-OT, 17.1 months; PostOP-OT, 8.2 months in Park et al; vs. TT 18.1, months; Pre-OP-OT, 10.1 months; Post-OP-OT, 6.8 months in this study; Tables 3 and 5).
TABLE 3. Comparison of Treatment Duration Between Groups 1 and 2 Group 1 (CTM; n = 26; 11 Males and 15 Females)
Group 2 (SFA; n = 18; 7 Males and 11 Females)
Duration
Mean
SD
Mean
SD
P
TT (days)
647.15 416.27 194.35
215.66 185.04 93.22
322.94 30.56 257.61
129.88 29.40 133.08
