Original Article

Influence of second premolar extractions on the volume of the oral cavity

proper: a control comparative cone-beam computed tomography
volumetric analysis study
Miodrag Mladenovica; Simon Freezerb; Craig Dreyerc; Maurice J. Meaded

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ABSTRACT
Objectives: To compare the pre- and postorthodontic treatment volumetric changes of the oral
cavity proper (OCP) in extraction and nonextraction patients and to identify influencing variables.
Materials and Methods: Pre- and posttreatment cone-beam computed tomography (CBCT)
scans of patients undergoing orthodontic treatment with fixed labial appliances and who satisfied
the inclusion criteria were individually landmarked. Linear, angular, and volumetric measure-
ments were determined. Descriptive statistics, repeated measure analyses of variance, correla-
tions, and stepwise regression statistical analyses were applied.
Results: The CBCT scans of 54 patients who underwent the extraction of second premolars and/or
extraction of second primary molars associated with agenic second premolars, and 59 nonextraction
patients matched for crowding, were assessed. The mean age for both groups was 15 years. There
was a statistically significant increase in the volume of the OCP for both the extraction and nonextrac-
tion groups, with the nonextraction group demonstrating a larger increase in the volume of the OCP.
Gender, age, changes in mandibular and maxillary arch length, and changes in mandibular and max-
illary intermolar width all influenced the change in the OCP volume.
Conclusions: The volume of the OCP increased in growing patients with and without the extrac-
tion of the second premolars and/or extraction of second primary molars associated with agenic
second premolars. Patients who did not have extractions as part of their orthodontic treatment
demonstrated a greater overall increase in OCP volume. (Angle Orthod. 2024;94:31–38.)
KEY WORDS: Cone-beam computed tomography (CBCT); Extraction; Oral cavity proper volume

INTRODUCTION broadly divided into two parts: the vestibule and the
oral cavity proper (OCP).1 The OCP lies internal to
Notwithstanding the difficulty in accurately defining
the maxillary and mandibular dental arches. The
and measuring the oral cavity, the mouth can be
superior border is formed by the hard and soft pal-
ates, whereas the inferior border is formed by the
a
Postgraduate Student, Adelaide Dental School, The University tongue and the soft tissue structures of the floor of
of Adelaide, Adelaide, Australia. the mouth.1 It is separated from the oropharynx via
b
Teaching Lecturer, Adelaide Dental School, The University a ring of structures that include the soft palate, ante-
of Adelaide, Adelaide, Australia and Private Practice, Adelaide,
Australia.
rior tonsillar pillars, the pterygomandibular raphe,
c
Emeritus Professor, Adelaide Dental School, The University and posterior portion of the tongue.1,2 The terms
of Adelaide, Adelaide, Australia. intraoral, oral cavity, and OCP are frequently used
d
Associate Professor, PR Begg Chair in Orthodontics, Adelaide interchangeably. However, the term OCP will be used
Dental School, University of Adelaide, Adelaide, Australia. in this article.
Corresponding author: Dr Maurice J. Meade, Associate
Professor and PR Begg Chair in Orthodontics, Orthodontic Unit, Measurement of the size and volume of the OCP
Adelaide Dental School, Level 10, Adelaide Health and Medical has been carried out using a variety of methodologies
Sciences Building Corner of North Terrace and George St, including alginate and polyvinylsiloxane impressions,
Adelaide SA 5000, Australia
(e-mail: maurice.meade@adelaide.edu.au) lateral cephalometry, computed tomography (CT) scans,
and magnetic resonance imaging scanning.3–5 Although
Accepted: July 2023. Submitted: March 2023.
Published online: October 17, 2023 these have provided valuable information, potential
Ó 2024 by The EH Angle Education and Research Foundation, Inc. disadvantages are patient discomfort and, often, high

DOI: 10.2319/031023-164.1 31 Angle Orthodontist, Vol 94, No 1, 2024

32 MLADENOVIC, FREEZER, DREYER, MEADE

Table 1. Landmarks Used and consequent predisposition for obstructive sleep

Upper left and right central incisor apnea (OSA).2,7
Lower left and right central incisor Extraction of teeth as part of an orthodontic treat-
Upper left and right first permanent molar ment plan has long been practiced and remains con-
Lower left and right first permanent molar
Lingula
troversial.8 The debate regarding the impact of
Hamulus notch left and right orthodontically prescribed extractions on temporo-
Menton mandibular joint dysfunction and dental and facial
A point esthetics is ongoing.9–12 Several researchers have
B point indicated that a new concern has emerged that con-
Gonion left and right
Anterior nasal spine
tends that shortening of the dental arch length after
Posterior nasal spine orthodontic treatment by premolar extractions results

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Sella in a reduction of the OCP volume.13,14 This may result
Nasion in insufficient space for the tongue, which may subse-
quently negatively influence the airway. It is essential,
therefore, that orthodontists understand the potential
radiation dosage. The advent of cone-beam computed clinical consequences of changes in OCP volume as a
tomography (CBCT) has created an opportunity for result of orthodontic treatment.
three-dimensional assessment of the OCP, with the The volumetric changes to the OCP as a result of
ability to obtain more accurate linear and volumetric orthodontic extractions has not been previously inves-
measurements while keeping costs and radiation expo- tigated. The aim of this study was to compare the pre-
sure at acceptable levels.4,6 and postorthodontic treatment volumetric changes of
A large tongue in a normally sized OCP or a nor- the OCP in a sample of patients undergoing extraction
mal tongue in a smaller OCP has been linked to mal- and nonextraction orthodontic treatment. The null
occlusions, as observed in Beckwith-Wiedemann hypothesis was that the volume of the OCP would not
syndrome in which tongue enlargement results in change as a result of extractions prescribed as part of
lateral open bite and proclination of the lower denti- orthodontic treatment.
tion.7 It has also been hypothesized that a mismatch
MATERIALS AND METHODS
between tongue size and OCP creates an environ-
ment in which the tongue is obliged to rest posteri- Ethical approval for the investigation was provided
orly, which may result in restriction of the airway by the University of Adelaide. A power study indicated

Figure 1. Screen capture image of the landmarking program.

Angle Orthodontist, Vol 94, No 1, 2024

CHANGES IN OCP VOL IN EXTRACTION AND NONEXTRACTION PATIENTS 33

Table 2. Boundaries of the Intraoral Cavity Propera

Anterior boundary Bridging the palatal vault to the anterior incisor landmarks down to menton
Lateral boundary Bridging the maxillary incisors landmarks to the posterior molar landmarks of the upper and lower dentition
Superior boundary Palatal vault isolation bridging between along with ANS-PNS
Posterior boundary Bridging the PNS landmark with the left and right lingula, the lingula was then bridged to the gonion landmarks
Inferior boundary Outline of inferior surface of the mandible bridged to the apex of incisors anteriorly and lingual from gonion to posteriorly
a
ANS indicates anterior nasal spine; PNS, posterior nasal spine.

that a sample size of 37 was required to determine Once landmarking was completed, the CBCT slices
significance in a mean difference of 3000 mm3 in OCP were processed through a customized software pro-
volume between pretreatment (T0) and posttreatment gram for linear and volumetric calculations (Figure 1).

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(T1). The CBCT scans were oriented to a standardized
The database of a private orthodontic practice in position via the anterior nasal spine, posterior nasal
Adelaide, South Australia, was extensively audited for spine, and menton landmarks. The landmarks were
patients who had undergone comprehensive orthodontic connected via computerized bridging to generate con-
treatment between 2015 and 2021. The inclusion criteria tinuous anteroposterior and lateral boundaries of the
for selection were the following: OCP. Superior and inferior boundaries were set via
automated isolation of the hard tissues using the hard
• no history of previous orthodontic treatment, palate and inferior border of the mandible (Table 2,
• complete T0 and T1 CBCT scans with appropriate Figure 2).
extensions, Linear and angular measurements were collated as
• complete patient records, listed and defined in Table 3.
• no craniofacial deformities, and Following completion of landmarking, a voxel sen-
• single-phase treatment using Tip-Edge (TP Ortho- sitivity threshold was developed via a K-means clus-
dontics, La Porte, Ind.) full-fixed appliances. tering algorithm. This enabled differentiation of the
soft tissues, air, and hard tissue voxel radiodensities.
In addition, patients in the experimental group had The isolation of voxels was then used for the calculation
undergone extraction of both maxillary second premo- of the volume of the area defined by the landmarks.
lars or all second premolars or had agenic second pre- The volume was calculated in cubic millimeters and
molars in which the extraction of primary second was generated in a .text format by the program.
molars was required in addition to the contralateral pri- Data were recorded on an Excel spreadsheet
mary second molar or second premolar. (Microsoft Corp, Redmond, Wash). Descriptive statis-
The control group was selected to match the level of tics were calculated in means and percentages. Con-
crowding of the experimental group. Both groups were
tinuous variables were compared using t-tests, and
divided into two subgroups according to the level of T0
categorical variables were compared using the chi-
crowding: mild or moderate/severe.
square test to determine whether the groups were
CBCT images of the patients were obtained using
comparable at baseline. The Shapiro-Wilk test was
a Carestream Health CS9300 scanner; Carestream
applied to test for normality. The underlying assump-
Health, Rochester, N.Y.), with each voxel measur-
tions for the parametric tests were examined for each
ing 0.3 mm 3 0.3 mm 3 0.3 mm and a scan time of
analysis. No adjustments were required for the nor-
12–20 seconds. The standardized image acquisition
malization of the data. The normality assumptions
protocol required patients to breathe in and position
were confirmed via the homogeneity of variance and
the tongue on the palate during exposure. Acquired
Levene’s test.
data sets had approximately 442 images saved in
Digital Imaging and Communications in Medicine
format. The images were first cleaned of noise by a
combination of blurring, cropping, and ray-tracing
the affected regions to reconstruct the density val-
ues that were deemed to interfere with the smooth-
ness required to observe the landmarks and perform
calculations.
The landmarks for evaluation were identified and
placed manually by Dr Mladenovic (Table 1).15 A
screen capture of the landmarking program is shown Figure 2. Example of the two-dimensional reconstruction image of
in Figure 1. boundaries selected for calculation.

Angle Orthodontist, Vol 94, No 1, 2024

34 MLADENOVIC, FREEZER, DREYER, MEADE

Table 3. Linear and Angular Definitionsa

Max AL Linear measurement from a fixed vertical plane at PNS perp to the ANS-PNS plane to the 11 Inc edge
Man AL Linear measurement from a fixed vertical plane at PNS that is perpendicular to the ANS-PNS plane to the 31 Inc edge
Max IMW Measurement from the MB cusp of 16 to 26
Man IMW Measurement from the MB cusp of 36 to 46
Man Inc Ang Ang of 31 in relation to the Man plane
Max Inc Ang Ang of 11 in relation to ANS-PNS plane
Inter Gonial Dist Dist between the left and right Gonion landmarks
Max–Man angle Ang of the ANS-PNS plane with Man plane angle
ANB angle Difference of angles SNA and SNB
a
AL indicates arch length; Ang, angulation; ANS, anterior nasal spine; Dist, distance; IMW, intermolar width; Inc, incisor; Man, mandibular;
Max, maxillary; MB, mesiobuccal; and PNS, posterior nasal spine. SNA, Angle formed by the intersection of sella-nasion and nasion-A lines;

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SNB, Angle formed by the intersection of sella-nasion and nasion-B lines.

Repeated measures analyses of variance tests were and nonextraction groups over time, with the nonextrac-
performed to test for differences across time and tion group increasing by a comparatively greater amount
between groups (extraction vs nonextraction). The than the extraction group (F1,53 ¼ 12.0, P ¼ .001).
significance was set at P
.05. Figure 4 shows that, regardless of the level of crowd-
Correlation testing was used to assess for linear rela- ing, OCP volume increased at the same rate over time.
tionships to explore potential influences on the change There was no significant difference in the rate of volume
in intraoral volume. This was followed by regression and increase between patients with different levels of crowd-
multiple regression analyses to identify confounders. ing (F1,111 ¼ 0.25, P ¼ .875).
Statistical analyses were carried out using SPSS statis- Table 5 shows the association of variables with
tics software version 27 (IBM, Armonk N.Y.). changes in OCP, and Table 6 illustrates that there was
no difference in the linear measurements between the
RESULTS extraction and nonextraction groups at T0, but statisti-
cally significant differences were present at T1 and in
Application of inclusion criteria resulted in 54 patients the differences between T0 and T1 (P
.05). Table 7
in the experimental (extraction) group and 59 patients shows that 11.9% of the difference in the change in OCP
in the control (nonextraction) group. Table 4 shows that volume was explained by gender.
there were no significant differences in age and gender Stepwise multiple regression analysis showed that
between the groups. the combination of mandibular arch length, gender,
Figure 3 shows that there was a significant (P ¼ .018) changes in maxillary intermolar width (IMW), and
increase in the OCP volume change in the extraction changes in maxillary arch length significantly influenced

Table 4. Descriptive Statistics of the Extraction and Nonextraction Groups (N ¼ 113)

Variable Nonextraction, n ¼ 59 Extraction, n ¼ 54 P Value
Sex, n (%) .42
Male 24 (41) 18 (33)
Female 35 (59) 36 (67)
Age, y
Mean age at T0 15.0 15.0 .743

15, n (%) 48 (81) 43 (80) .817
16, n (%) 11 (19) 11(20)
Skeletal classification, n (%)
Class I 42 (71) 21 (39) .001
Class II 17 (29) 33 (61)
Initial crowding, n (%)
Spacing/mild,
3 mm 25 (42) 25 (46) .675
Moderate/severe, .3 mm 34 (58) 29 (54)
Maxillo-mandibular angle, n (%)

24 38 (64) 26 (48) .102
25–31 18 (31) 25 (46)
32 3 (5) 3 (6)
Extraction, n (%)
Upper second premolars N/A 20 (37) N/A
Four second premolars N/A 34 (63)
Average treatment length, months, n (%) 21.5 (7.0) 23.5 (6.4) .11
a
N/A indicates not applicable; T0, pretreatment.

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CHANGES IN OCP VOL IN EXTRACTION AND NONEXTRACTION PATIENTS 35

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Figure 3. Pretreatment (T0) and posttreatment (T1) changes in the oral cavity proper volume.

the difference in intraoral volume between the two The adoption of the hyoid bone as a landmark, sug-
groups, with an adjusted R2of 0.29 being recorded. gested by Halim et al, was not used in the present
This indicated that a clinical alteration of those factors study as it has been found to be unreliable and poten-
influenced the intraoral volume and the impact of having tially negatively influenced by head posture.16,17 The
an extraction became less significant. landmarks selected to create the OCP boundaries in the
present investigation were based on previous studies
DISCUSSION that showed acceptable reliability and reproducibility.15
Delineation of the oropharynx from the OCP boundaries
This was the first study to investigate and compare in the present investigation was in agreement with the
the T0 and T1 volumetric changes of the OCP in patients anatomical definitions set by Laine and Smoker.1
undergoing extraction and nonextraction orthodontic The present study indicated that males demonstrated
treatment. The findings indicated that the volume of the greater changes in OCP volume than females. Previ-
OCP increased in all patients, with those undergoing ous similar studies did not report on gender and age dif-
nonextraction treatment experiencing a greater volume ferences, so comparisons with other investigations was
increase. The investigation and findings are clinically not possible. However, as the mean age of both cohorts
relevant as potential OCP volume loss in extraction was 15 years old, it is reasonable to consider that the
cases may be associated with a potential increased risk male participants were undergoing comparatively greater
of OSA. growth between evaluation timepoints.18,19 In addition,
Variations in the definition of what constitutes the the morphological differences in craniofacial pattern
OCP and the landmarks used to determine its borders between male and female participants were likely to
made comparisons with other studies challenging.16 influence changes in intraoral volume.18,19

Figure 4. Pretreatment (T0) and posttreatment (T1) changes in the oral cavity proper volume based on the level of crowding.

Angle Orthodontist, Vol 94, No 1, 2024

36 MLADENOVIC, FREEZER, DREYER, MEADE

Table 5. Association of Variables With Changes in OCP A reduction in mandibular arch length of up to 12.1
r P Value mm as a result of premolar extraction has been previ-
Age 0.259 .006 ously reported.12,20–23 In the present study, the man-
Max AL 0.235 .012 dibular arch length in the extraction sample reduced
Man AL 0.396 ,.001 by 0.94 mm. By contrast, the increase in the mandibu-
Max IMW 0.278 .012 lar arch length in nonextraction patients in the present
Man IMW 0.248 .008
study of 2.19 mm was comparable with the increase of
a
AL indicates arch length; IMW, intermolar width; Man, mandibular; up to 2.9 mm reported elsewhere.12 The variation in
Max, maxillary; and OCP, oral cavity proper. arch length reduction may have been because the
measurement of arch length was from a reliable fixed
The changes to mandibular and maxillary arch length point (a vertical plane perpendicular to posterior nasal

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resulting from different treatment modalities have been spine) rather than a mobile reference point (such as a
previously reported.12,20 The change to mandibular arch plane connecting the contralateral mesial cusps of
length was found to be responsible for 15% of the permanent molars).20
variance of OCP volume between T0 and T1 measure- In addition, the combination of the extraction of sec-
ments, whereas the maxillary arch length was responsi- ond permanent premolars and the treatment mechan-
ble for 6% of the variance. ics associated with the Tip-Edge appliance may have
resulted in the minimal arch length reduction observed
in the present study. Ongoing growth of the maxilla
Table 6. Comparison of Linear Measurements Between the and mandible may also have negated some of the
Extraction (n ¼ 54) and Nonextraction (n ¼ 59) Groupsa
potential arch length reduction.24
Variable Mean (SD), mm P Value* The changes in the mandibular (38%) and maxillary
Max AL (T0) (25%) IMWs were shown to contribute significantly to
Nonextraction 49.98 (4.77) .66 the differences in the OCP volume in both extraction
Experimental 50.47 (7.03)
Max AL (T1)
and nonextraction patients. The reduction of 0.08 mm
Nonextraction 50.57 (4.10) .001 in the mandibular IMW in the nonextraction group and
Extraction 47.68 (6.03) 2.73 mm in the extraction group were similar to that
Max AL difference (T0–T1) previously reported.22,23 The present findings showed
Nonextraction 0.59 (2.64) ,.001 a minor reduction in maxillary IMW in the control sam-
Extraction 2.79 (5.54)
Man AL (T0)
ple, 0.08 mm, and a more significant reduction in the
Nonextraction 46.11 (4.39) .74 extraction group of 2.11 mm. This also corresponded
Extraction 46.48 (7.00) to findings in previous studies.19,22 However, it has
Man AL (T1) been contended that the mesialization of the molars
Nonextraction 48.30 (3.87) .01 into the relatively narrower anterior dental arch may
Extraction 45.54 (5.91)
Man AL difference (T0–T1)
be responsible for the apparent reduction of the IMW
Nonextraction 2.19 (2.08) ,.001 rather than a reduction of the radius of the curve of the
Extraction 0.94 (5.04) arch and a subsequent loss of OCP volume.25 Future
Max IMW (T0) studies should consider placing landmarks on all avail-
Nonextraction 39.71 (2.50) .45 able teeth in the arch or develop a novel way of over-
Extraction 39.31 (3.15)
Max IMW (T1)
coming the problem of defining the lateral boundaries
Nonextraction 39.63 (5.00) .001 created in the present study.
Extraction 37.20 (3.24) A strength of the study was the use of key landmarks
Max IMW difference (T0–T1) that were shown to be reliable and reproducible.
Nonextraction 0.08 (5.29) .01 Although the risk of selection bias was identified as
Extraction 2.11 (2.55)
Man IMW (T0)
a limitation of the study, the risk was minimized by the
Nonextraction 44.55 (2.53) .50 strict adherence to the inclusion and exclusion criteria.
Extraction 44.22 (2.75) In addition, a lack of reliability in orientation of the
Man IMW (T1) image and the selection of the sensitivity threshold are
Nonextraction 44.25 (2.14) ,.001 potential risks in all volumetric studies.
Extraction 41.49 (3.19)
Man IMW difference (T0–T1)
A future study is required to further determine the
Nonextraction 0.31 (2.11) ,.001 clinical and nonclinical parameters that may influence
Extraction 2.73 (2.69) the OCP volume. Additional research is also required
a
AL indicates arch length; IMW, intermolar width; Man, mandibular;
to investigate OCP volume changes in nongrowing
Max, maxillary; SD, standard deviation; T0, pretreatment; and T1, patients and in those treated with other fixed and remov-
posttreatment. able orthodontic appliances.

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CHANGES IN OCP VOL IN EXTRACTION AND NONEXTRACTION PATIENTS 37

Table 7. Regression Analysis Showing the Impact of Extraction, Gender, Age, Max AL, Man AL, Max IMW, and Man IMW on the Volume of
OCPa
Unstandardized
Standardized
Coefficients
Coefficients
Variable Model Adjusted R2 B Std. Error b t Significance
Extraction 1 0.041 (Constant) 8118.0 1096.46 7.40 .000
Extraction 3814.45 1586.11 0.22 2.41 .018
Gender 1 .119 (Constant) 11189.34 1406.79 7.95 .000
Extraction 3434.19 1524.89 0.20 2.25 .026
Gender 5177.38 1576.18 0.29 3.28 .001
Age 1 .104 (Constant) 15223.05 2614.39 5.82 .000
Extraction 3956.61 1533.67 0.23 2.58 .011

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Age 474.74 159.69 0.27 2.97 .004
Max AL 1 .060 (Constant) 7921.454 1091.064 7.260 .000
Extraction 2690.317 1690.129 0.157 1.592 .114
Change in Max AL 332.876 185.032 0.177 1.799 .075
Man AL 1 .147 (Constant) 6444.873 1121.702 5.746 .000
Extraction 1421.919 1619.845 0.083 0.878 .382
Change in Man AL 764.646 198.691 0.364 3.848 .000
Max IMW 1 .087 (Constant) 8155.440 1070.022 7.622 .000
Extraction 2849.326 1592.837 0.166 1.789 .076
Change in Max IMW 475.383 185.395 0.238 2.564 .012
Man IMW 1 .060 (Constant) 8299.843 1090.147 7.614 .000
Extraction 2373.556 1761.559 0.138 1.347 .181
Change in Man IMW 594.492 329.411 0.185 1.805 .074
a
AL indicates arch length; IMW, intermolar width; Man, mandible; Max, maxilla; OCP, oral cavity proper; and Std., standard. Significance
set at P
.05.

CONCLUSIONS and volumetric changes of the tongue and oral cavity before
and after orthognathic surgery for mandibular prognathism: a
• The volume of the OCP increased in all patients. preliminary study. Prog Orthod. 2020;21:1–10.
• Nonextraction cases had a greater volume increase. 6. Sacksteder J, Firestone A, Kim DG. Comparison of dental
• Changes to mandibular and maxillary arch length, arch width and length parameters in patients with obstruc-
gender, and maxillary IMW contributed to the changes tive sleep apnea and a control group: a pilot study. J Dent
in the volume of the OCP. Sleep Med. 2021;8(3).
7. Rajkumar B, Parameswaran R, Parameswaran A,
ACKNOWLEDGMENT Vijayalakshmi D. Evaluation of volume change in oral cavity
proper before and after mandibular advancement: a retrospec-
The authors acknowledge the support provided by the tive volumetric study. Angle Orthod. 2021;91:81–87.
Australian Society of Orthodontists Foundation for Research 8. Meade MJ, Dreyer CW. Orthodontic extraction practices: a
and Education. The funding body did not have any role in the cross-sectional survey of orthodontists in Australia. Aust Orthod
study design, collection, analysis, interpretation, or writing of J. 2022;38:227–236.
the manuscript. 9. Bowman SJ, Johnston LE. The esthetic impact of extraction
and nonextraction treatments on Caucasian patients. Angle
REFERENCES Orthod. 2000;70:3–10.
10. Wholley CJ, Woods MG. The effects of commonly pre-
1. Laine FJ, Smoker WR. Oral cavity: anatomy and pathology.
scribed premolar extraction sequences on the curvature of
Semin Ultrasound CT MR. 1995;16:527–545.
the upper and lower lips. Angle Orthod. 2003;73:386–395.
2. Rana SS, Kharbanda OP, Agarwal B. Influence of tongue
11. McLaughlin RP, Bennett JC. The extraction–nonextraction
volume, oral cavity volume and their ratio on upper airway: a
dilemma as it relates to TMD. Angle Orthod. 1995;65:175–186.
cone beam computed tomography study. J Oral Biol Cranio-
fac Res. 2020;10:110–117. 12. Paquette DE, Beattie JR, Johnston LE Jr. A long-term com-
3. Takada K, Sakuda M, Yoshida K, Kawamura Y. Relations parison of nonextraction and premolar extraction edgewise
between tongue volume and capacity of the oral cavity proper. therapy in “borderline” Class II patients. Am J Orthod Dento-
J Dent Res. 1980;59:2026–2031. facial Orthop. 1992;102:1–4.
4. Ding X, Suzuki S, Shiga M, Ohbayashi N, Kurabayashi T, 13. Wang Q, Iia P, Anderson NK, Wang L, Lin J. Changes of
Moriyama K. Evaluation of tongue volume and oral cavity pharyngeal airway size and hyoid bone position following
capacity using cone-beam computed tomography. Odontol. orthodontic treatment of Class I bimaxillary protrusion. Angle
2018;106:266–273. Orthod. 2012;82:115–121.
5. Teramoto A, Suzuki S, Higashihori N, Ohbayashi N, 14. Germec-Cakan D, Taner T, Akan S. Uvulo-glossopharyng-
Kurabayashi T, Moriyama K. 3D evaluation of the morphological eal dimensions in non-extraction, extraction with minimum

Angle Orthodontist, Vol 94, No 1, 2024

38 MLADENOVIC, FREEZER, DREYER, MEADE

anchorage, and extraction with maximum anchorage. Eur J 20. Boley JC, Mark JA, Sachdeva RC, Buschang PH. Long-term
Orthod. 2011;33:515–520. stability of Class I premolar extraction treatment. Am J Orthod
15. Naji P, Alsufyani NA, Lagravère MO. Reliability of ana- Dentofacial Orthop. 2003;124:277–287.
tomic structures as landmarks in three-dimensional ceph- 21. Shapiro PA. Mandibular dental arch form and dimension:
alometric analysis using CBCT. Angle Orthod. 2014;84: treatment and postretention changes. Am J Orthod. 1974;
762–772. 66:58–70.
16. Ryan DPO, Bianchi J, Ignácio J, Wolford LM, Gonçalves JR. 22. Luppanapornlarp S, Johnston LE. The effects of premolar-
Cone-beam computed tomography airway measurements: extraction: a long-term comparison of outcomes in “clear-cut”
can we trust them? Am J Orthod Dentofacial Orthop. 2019; extraction and nonextraction Class II patients. Angle Orthod.
156:53–60. 1993;63:257–272.
17. Halim IA, Park JH, Liou EJ, Zeinalddin M, Al Samawi YS, 23. Shearn BN, Woods MG. An occlusal and cephalometric anal-
Bay RC. Preliminary study: evaluating the reliability of ysis of lower first and second premolar extraction effects. Am
CBCT images for tongue space measurements in the field J Orthod Dentofacial Orthop. 2000;117:351–361.

Downloaded from http://meridian.allenpress.com/angle-orthodontist/article-pdf/94/1/31/3302821/i1945-7103-94-1-31.pdf by guest on 09 August 2024

of orthodontics. Oral Radiol. 2021;37:256–266. 24. Bishara SE, Jakobsen JR, Treder J, Nowak A. Arch length
18. Bishara SE. Facial and dental changes in adolescents and changes from 6 weeks to 45 years. Angle Orthod. 1998;68:
their clinical implications. Angle Orthod. 2000;70:471–483. 69–74.
19. Bishara SE, Peterson LC, Bishara EC. Changes in facial 25. Johnson DK, Smith RJ. Smile esthetics after orthodontic
dimensions and relationships between the ages of 5 and 25 treatment with and without extraction of four first premolars.
years. Am J Orthod. 1984;85:238–252. Am J Orthod Dentofacial Orthop. 1995;108:162–167.

Angle Orthodontist, Vol 94, No 1, 2024