transverse growth of the maxilla and mandible in untreated girls with low, average, and high mp sn...

ORIGINAL ARTICLE

Transverse growth of the maxilla and mandiblein untreated girls with low, average, and highMP-SN angles: A longitudinal studyDawn M. Wagnera and Chun-Hsi Chungb

Philadelphia, Pa

Introduction: The purpose of this study was to investigate maxillary and mandibular transverse growth inuntreated female subjects with low, average, and high mandibular plane angles longitudinally from ages 6 to 18.Methods: Eighty-one untreated white girls with low (� 27°, n � 16), average (� 27° to � 37°, n � 41), andhigh (� 37°, n � 24) mandibular plane angles at age 6 were selected from the Bolton-Brush and BurlingtonGrowth Studies. For each subject, longitudinal posteroanterior cephalograms at different ages (from ages 6to 18) were traced, and the widths of maxilla and mandible were measured. All the measurements wereconverted by using a magnification factor of 8.5% (the subject-to-film distance was set at 13 cm). Results:At age 6, the high-angle group had narrower maxillary and mandibular widths than the low-angle group, andthis trend continued until age 18. From ages 6 to 14, maxillary width showed a steady and similar rate ofincrease for all 3 groups (0.90-0.95 mm per year), yet a plateau was reached at age 14 for all groups.Mandibular width increased at a steady rate (about 1.6 mm/year) for all 3 groups until age 14, and a plateauwas reached for the high-angle group. For the low- and average-angle groups, mandibular growth continuedfrom ages 14 to 18 but at a slower rate (0.85 mm and 0.39 mm per year, respectively). Conclusions: Verticalfacial patterns (with low or high mandibular plane angles) might play a strong role in the transverse growth
of the maxilla and the mandible. (Am J Orthod Dentofacial Orthop 2005;128:716-23)
It is well known that, during growth, the changes insize and shape of the facial bones are determinedby sutural, cartilagenous, and periosteal and en-

dosteal bone deposition and resorption (remodeling).1

Soft tissues relating to the bones and functional needsare believed to play an important role in the remodelingprocess.1-5

The influence of jaw muscles on facial form hasintrigued many investigators. Finn6 reported that max-imum biting force in the molar region was greater inbrachyfacial (short-face) subjects than in dolichofacial(long face) subjects. Proffit et al7 found that long-faceadults have significantly less occlusal force duringmaximum-effort, simulated chewing and swallowingthan do subjects with normal vertical facial dimensions.Christie8 evaluated orthodontic records of 82 whiteadults (43 women, 39 men) with normal untreatedocclusions and found that short-face men had greater

From the Department of Orthodontics, School of Dental Medicine, Universityof Pennsylvania, Philadelphia.aFormer orthodontic resident; US Air Force.bAssociate professor.Reprint requests to: Dr Chun-Hsi Chung, Department of Orthodontics, Univer-sity of Pennsylvania School of Dental Medicine, Robert Schattner Center,240 S 40th St, Philadelphia, PA 19104-6030; e-mail, [email protected], May 2004; revised and accepted, September 2004.0889-5406/$30.00Copyright © 2005 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2004.09.028
716

maxillary and mandibular widths than normal men.However, no differences in width were found betweenshort-face and normal women. They did not providedata on long-face subjects because the sample size wastoo small (only 4). Weijs and Hillen9 and van Sprosenet al10 found that the cross-sectional areas of thetemporalis and masseter muscles correlated positivelywith facial width. They suggested that the jaw musclesaffect facial growth and partly determine the final facialdimensions. Kiliaridis11 also suggested that the increasedloading of the jaws from masticatory muscle hyperfuctionmight lead to increased sutural growth and bone apposi-tion, resulting in increased transversal growth of themaxilla and broader bone bases for the dental arches.Tsunori et al12 reported that, when compared withaverage and long-face persons, short-face subjects hadlarger intermolar widths and greater buccal corticalbone thicknesses in the molar area of the mandible.They suggested a possible link between the develop-ment of the maxillofacial complex in the vertical andtransverse dimensions and measures of increased mus-cularity.

Clinicians often pay much attention to the inclina-tion of the mandibular plane, because it is a majordeterminant of the vertical dimension of a face (long,average, or short). A person with a steeper mandibular
plane to cranial base (larger MP-SN angle) often has a

American Journal of Orthodontics and Dentofacial OrthopedicsVolume 128, Number 6

Wagner and Chung 717

long anterior facial height, a smaller ratio of posteriorto anterior facial height, and a short mandibular ramusheight. Conversely, a person with a flat mandibularplane (smaller MP-SN angle) has a short anterior facialheight, a larger ratio of posterior to anterior facialheight, and a long mandibular ramus height.13-16 Thepurpose of this study was to investigate the maxillaryand mandibular transverse growth in untreated femalesubjects with low, average, and high MP-SN angleslongitudinally from ages 6 to 18.

MATERIAL AND METHODS

The sample consisted of 81 white girls, including31 from the Bolton-Brush Growth Study at Case

Fig 1. Hand-traced lateral cephalogram of subject atage 6. SNA, SNB, ANB, and MP-SN angles weremeasured.

Table I. Group descriptions at about age 6

Groups nMean

ANB (°)Range

(°)Mean

MP-SN (°)Range

(°)

Low-angle 16 2.19 0-5 26.19 21-27Average-angle 41 3.44 1-5 33.37 30-36High-angle 24 3.33 1-5 38.70 37-44

Western Reserve University in Cleveland, Ohio, and 50

from the Burlington Growth Centre at the University ofToronto in Canada. The subjects were selected basedon the following criteria: (1) lateral and posteroanterior(PA) cephalograms available at about age 6 and longi-tudinal PA cephalograms available every 1-3 years toabout age 18, (2) ANB angle between 0° and 5° at age6, (3) normal maxillary and mandibular arch formswithout anterior or posterior crossbite, (4) in goodhealth with no history of head or facial trauma, steroidor growth-hormone therapy, or orthodontic treatment.

The definitions of the landmarks of the PA andlateral cephalograms corresponded to those given byRicketts et al17 and Riolo et al.18 For each subject, thelateral cephalogram about age 6 was traced by hand onacetate paper by an examiner (D.M.W.), and the SNA,SNB, ANB, and MP-SN angles were measured (Fig 1).MP was defined as a line drawn from menton to theinferior border of the angular area of the mandible.13,15,16

The sample was divided into 3 groups according tothe MP-SN angles at age 6: (1) low angle (� 27°,n � 16), (2) average angle (�27° to �37°, n � 41), and(3) high angle (� 37°, n � 24). These MP-SN valuesrepresented about 1 SD from the mean MP-SN angle of

Fig 2. Jugale (J): at jugal process, intersection of out-line of tuberosity of maxilla and zygomatic buttress; andantegonion (Ag): at antegonial notch, lateral inferiormargin of antegonial protuberances.

children aged 8 to 11 reported by Riedel.19 The mean

American Journal of Orthodontics and Dentofacial OrthopedicsDecember 2005

718 Wagner and Chung

MP-SN angles at about age 6 were 26.19° for thelow-angle group, 33.37° for the average-angle group,and 38.70° for the high-angle group (Table I). Themean ANB angles were 2.19° (low angle), 3.44°(average angle), and 3.33° (high angle) (Table I).

Each subject’s PA cephalogram for each age wastraced on acetate paper by an examiner (D.M.W.).The following landmarks were identified: jugale (J),at the jugal process, the intersection of the outline ofthe tuberosity of the maxilla and the zygomaticbuttress; and antegonion (Ag), at the antegonial notch,the lateral inferior margin of the antegonial protuber-

Table II. Transverse maxillary growth (mm) from ages 6significance between groups; measurements calculatedof 8.5%

Age

Low-angle group Average-angle group

n J-J SD n J-J SD

6 11 57.47 1.88 36 56.66 2.77 7 58.66 1.26 23 57.99 2.78 9 59.77 1.61 26 59.57 2.49 12 60.75 2.2 40 60.95 2.6

10 10 62.8 2.16 34 62.26 2.711 10 63.74 2.93 27 63.18 2.612 16 63.52 2.87 45 63.09 2.513 10 64.4 2.34 30 63.9 2.514 16 64.15 2.15 38 64.21 2.415 6 64.79 2.32 18 64.09 2.516 15 64.41 1.9 35 64.3 2.417 5 64.53 2.92 19 64.26 2.918 5 64.57 3.15 17 63.6 2.4

J, jugale; L, low angle; A, average angle; H, high angle.*Statistically significant.

Table III. Predicted transverse maxillary growth (mm)from regression analysis of data in Table II

Age

Predicted J-J

Low-angle Average-angle High-angle

6 58.07 57.50 55.857 58.97 58.45 56.748 59.88 59.41 57.639 60.79 60.36 58.53

10 61.70 61.31 59.4211 62.60 62.27 60.3112 63.51 63.22 61.2113 64.42 64.17 62.1014 65.32 65.13 62.9915 65.38 65.02 62.9316 65.44 64.92 62.8617 65.50 64.81 62.8018 65.56 64.71 62.74

J, jugale.

ances (Fig 2).17 The distances of J-J, and Ag-Ag were

measured with a digital caliper (Orthopli, Philadelphia,Pa), accurate to 0.01 mm.

Because subjects from 2 growth studies were ex-amined, all linear measurements had to be convertedbecause of different enlargement factors for eachcephalostat. At the Burlington Growth Centre, all PAcephlaograms, regardless of the subject’s age, weremagnified by 9.84%. The anode-to-subject distance andthe film-to-porionic axis distance (FPD) were set at152.4 cm and 15 cm, respectively.20 In the Bolton-Brush Growth Study, magnification was regulated ac-cording to the subject’s age (age 6-7, 7.2%; age 8,7.4%; age 9-10, 7.5%, age 11, 7.7%; age 12, 7.9%; age13, 8.0%; age 14, 8.1%; age 15-16, 8.2%; age 17-18,8.4%).21 Because 13 cm is commonly used in Americaninstitutions and practices as the FPD, all J-J and Ag-Agvalues were converted to the recommended distance of 13cm FDP with a magnification factor of 8.5%.22

In addition, 6 subjects were randomly selected, andtheir PA cephalograms for each age (total, 39 films)were retraced and remeasured by the same examiner(D.M.W.) to assess whether any intraexaminer errorresulted from landmark selection, tracing, and measure-ment error. The same measurements were made in thesubjects to be studied. Also, 6 subjects were randomlychosen, and their PA cephalograms for each age (total,47 films) were traced and measured by another exam-iner to determine the interexaminer reliability. Pearsoncorrelation analysis and the paired Student t test wereconducted for all first and second linear and angular

for low average- and high-angle groups and statisticalon 13-cm subject-to-film distance with magnification

High-angle group P value

n J-J SD L vs A A vs H L vs H

19 55.74 2.38 0.14 0.10 0.02*14 56.6 2.06 0.19 0.04* 0.01*19 57.35 1.66 0.39 0.00* 0.00*21 58.46 2.23 0.40 0.00* 0.00*19 59.67 1.96 0.26 0.00* 0.00*16 61.1 2.46 0.30 0.01* 0.01*22 61.23 2.77 0.30 0.01* 0.01*16 62.52 2.73 0.29 0.05* 0.04*23 62.1 2.63 0.46 0.00* 0.01*4 61.63 1.3 0.27 0.01* 0.01*

23 62.3 3.07 0.43 0.01* 0.01*11 61.61 2.83 0.43 0.01* 0.05*10 61.79 3.36 0.28 0.08 0.08

to 18based

3

53425666962

measurements to determine whether they were signifi-



cantly different. The significance of differences waspredetermined at P � .05.

The mean and standard deviation for J-J and Ag-Ag, and the ratio of J-J to Ag-Ag from ages 6 to 18were computed, and the regression analysis was per-formed. The differences of each variable between thegroups were tested with the Student 2-tailed t test. Thesignificance of differences was predetermined at P � .05.

RESULTS

The intraexaminer reliability measurement showeda high correlation, with r � 0.96 and r � 0.99 betweenrepeated measurements for J-J and Ag-Ag, respec-tively. Interexaminer reliability showed a high correla-tion, with r � 0.91 and r � 0.95 between repeatedmeasurements for J-J and Ag-Ag, respectively.

Table II shows the longitudinal maxillary width(J-J) of each group and statistical data between thegroups from ages 6 to 18. Table III and Figure 3represent the predicted longitudinal width of the max-illa determined from a regression analysis of the data inTable II. The maxillary width in the low-angle groupwas 57.47 mm at age 6 and increased to 64.57 mm byage 18. The J-J of the average-angle group was 56.66mm at age 6 and increased to 63.60 mm at age 18, andthe high-angle group was 55.74 mm at age 6 and 61.79mm at age 18. A steady width increase was seen fromages 6 to 14; then a plateau was seen until age 18 for all3 groups. From ages 6 to14, the growth rates were 0.90mm per year for the low- and high-angle groups and0.95 mm for the average-angle group.

Table IV shows the longitudinal mandibular width(Ag-Ag) from ages 6 to 18. Table V and Figure 4represent the predicted Ag-Ag determined from a

Fig 3. Predicted transverse maxillary growth (ages 6 to 18.

regression analysis of the data in Table IV. The growth

of Ag-Ag in the low-angle group displayed a steadyincrease from 73.50 mm at age 6 to 85.74 mm at age14—a rate of 1.57 mm per year—and then a slower rate(0.85 mm per year) from ages 14 to 18. In theaverage-angle group, Ag-Ag was 72.87 mm at age 6and increased to 85.36 mm at age 14. A steady increasewas noted from ages 6 to 14 at a rate of 1.55 mm peryear, and then a decrease in rate (0.39 mm) was notedfrom ages 14 to 18. The high-angle group started at72.18 mm at age 6 and increased to 84.81 mm at age14. A steady increase was noted from ages 6 to 14 at arate of 1.57 mm per year, and then a plateau was seenfrom ages 14 to 18.

Table VI shows the annual ratio of J-J to Ag-Agfrom ages 6 to 18. Table VII and Figure 5 represent thepredicted ratio values generated from a regressionanalysis of the data in Table VI. The ratio generallydecreased as the ages of subjects increased. In thehigh-angle group, there was a plateau in the ratio fromages 14 to 18. The ratio tended to be smaller in thehigh-angle group than in the other groups.

DISCUSSION

We examined only untreated girls because male andfemale subjects have different sizes in all 3 dimen-sions.15,16,23,24 Unfortunately, many previous studies,in their measurements of linear transverse dimension,combined male and female subjects.17,22,25 Our sampleincluded 16 low-angle, 41 average-angle, and 24 high-angle girls. We gathered all information available at theBolton-Brush and Burlington growth studies for eachuntreated patient used in this study. Because of limitedrecords, we found only 16 low-angle subjects.

Because of different magnification factors, a direct

f low-, average-, and high-angle groups from
J-J) o
comparison could not be made between cephalograms



taken at a different FPD. To eliminate this factor, wecorrected the values of J-J and Ag-Ag to the recom-mended standard of 13 cm FPD with a magnification of8.5%.22 If clinicians desire to compare their PA ceph-alometric values to our data, they must first confirm thatthe FPD is the same before a valid comparison can bemade. We suggest that the FPD is required in reportingany linear cephalometric measurement; it is lacking insome reports.17,23,25,26

In our study, the maxilla had a steady transversegrowth rate from ages 6 to 14, but there was little or nogrowth after 14 years in all groups. Similar findings

Table IV. Transverse mandibular growth (mm) from astatistical significance between groups; measurementsmagnificantion of 8.5%

Age


n Ag-Ag SD n Ag-Ag SD

6 11 73.50 3.65 36 72.87 3.77 7 77.20 2.48 23 74.80 4.08 9 78.57 2.47 26 76.94 3.79 12 79.33 3.6 40 78.53 3.8

10 10 82.26 2.68 34 80.05 4.211 10 83.28 3.31 27 81.40 4.212 16 84.08 3.79 45 82.82 3.913 10 86.42 3.53 30 84.29 3.914 16 85.74 3.77 38 85.36 3.715 6 85.73 2.65 18 86.21 4.416 15 87.11 3.69 35 85.95 3.717 5 87.75 3.8 19 86.53 4.618 5 89.01 3.11 17 87.15 4.1

Ag, antegonion; L, low angle; A, average angle; H, high angle.*Statistically significant.

Table V. Predicted transverse mandibular growth (mm)from regression analysis of data in Table IV

Age

Predicted Ag-Ag


6 75.05 73.47 72.777 76.57 75.02 74.348 78.10 76.57 75.929 79.63 78.12 77.50

10 81.15 79.67 79.0811 82.68 81.22 80.6512 84.21 82.78 82.2313 85.73 84.33 83.8114 87.26 85.88 85.3815 88.12 86.27 85.2816 88.97 86.66 85.1817 89.83 87.05 85.0718 90.68 87.44 84.97

Ag, antegonion.

were reported by Cortella et al.27 Snodell et al26

showed that maxillary growth was complete for most ofhis female subjects by age 15. The Rocky Mountainanalysis of Ricketts et al,17 commonly used for diag-nosis of transverse dimensions of the maxilla andmandible, showed steady growth from ages 9 to 16.Yet, he did not separate his norms for boys and girls.For the mandible, we found steady growth from ages 6to 14 for all groups. But after 14, some differences werenoted. For the high-angle group, no more increase inAg-Ag was found, but the average-angle and low-anglegroups continued to grow to age 18. Snodell et al26

showed that girls’ mandibular growth continued untilage 18. Differently, Krogman28 suggested that growthin the width of both jaws tends to be completed beforethe adolescent growth spurt and is affected minimallyby adolescent growth changes.

In this study, little or no growth spurt was demon-strated in J-J and Ag-Ag for all groups. Thus, aregression analysis was performed, and the rate ofgrowth was determined for each group. For the maxilla,from ages 6 to 14, we found a similar rate oftransverse growth (0.90-0.95 mm per year) for allgroups. Differently, Ricketts et al17 reported 0.6 mmper year in J-J from ages 9 to 16. With implants,Björk and Skieller29,30 reported maxillary transversegrowth of 0.4 mm/year in 9 boys between 4 and 20years of age. Korn and Baumrind31 also studied trans-verse maxillary development longitudinally with im-plants in the zygomatic regions. They reported a meantransverse maxillary growth of 0.38 mm per year ingirls from ages 8.5 to 10.5 or 15.5 years. For the

to 18 for low- average- and high-angle groups andulated based on 13-cm subject-to-film distance with


n Ag-Ag SD L vs A A vs H L vs H

19 72.18 2.41 0.31 0.21 0.1514 74.40 3.85 0.04* 0.38 0.03*19 76.27 2.69 0.08 0.25 0.02*21 77.97 3.01 0.26 0.27 0.1419 78.84 2.58 0.03* 0.10 0.00*16 80.61 3.54 0.09 0.26 0.03*22 82.58 3.33 0.13 0.40 0.1116 84.02 3.95 0.06 0.42 0.0623 84.81 3.89 0.37 0.30 0.234 83.88 4.29 0.38 0.19 0.24

23 85.59 3.41 0.16 0.35 0.1111 83.60 3.12 0.28 0.02* 0.04*10 84.43 4.83 0.15 0.08 0.02*

ges 6calc

9588853867564

mandible, our data showed that Ag-Ag had a general

J, jugale; Ag, antegonion.



increase from ages 6 to 14 at a rate of 1.6 mm per yearfor all 3 groups. However, after age 14, there weredifferences between the groups. From ages 14 to 18, thelow-angle group had an increase of 0.85 mm per year,the average-angle group had a slower rate of growth of0.39 mm per year, and the high-angle group showed nogrowth. Ricketts et al17 reported that, from ages 9 to 16,the increase of Ag-Ag was 1.4 mm per year. Snodell etal26 reported an average of 1.3 mm per year increase inthe width of the mandible when measuring from themost lateral margin of the angle of the mandible.Regardless of the groups, in our study, the growth inmandibular width seemed to be different from that ofthe maxilla because Ag-Ag continued to increase pastage 14 in the low-angle and average-angle groups.

Ag) of low-, average-, and high-angle groups

rage-, and high-angle groups and statistical significance


n J-J/Ag-Ag SD L vs A A vs H L vs H

19 0.773 0.036 0.40 0.29 0.2614 0.762 0.037 0.13 0.16 0.4519 0.752 0.026 0.10 0.02* 0.1721 0.750 0.033 0.22 0.00* 0.1019 0.757 0.03 0.09 0.02* 0.2816 0.759 0.037 0.20 0.07 0.3122 0.743 0.034 0.29 0.02* 0.1516 0.745 0.033 0.15 0.10 0.4723 0.733 0.031 0.37 0.02* 0.084 0.737 0.048 0.25 0.38 0.25

23 0.728 0.03 0.20 0.01* 0.1311 0.738 0.037 0.33 0.33 0.4710 0.733 0.042 0.21 0.16 0.36

Fig 4. Predicted transverse mandibular growth (Ag-
from ages 6 to 18.
Table VI. Ratio of J-J to Ag-Ag from ages 6 to 18 in low-, avebetween groups

Age


n J-J/Ag-Ag SD n J-J/Ag-Ag SD

6 11 0.784 0.047 36 0.779 0.0517 7 0.760 0.025 23 0.777 0.0548 9 0.761 0.019 26 0.776 0.0469 12 0.767 0.035 40 0.776 0.039

10 10 0.764 0.026 34 0.779 0.04211 10 0.766 0.035 27 0.778 0.04312 16 0.757 0.043 45 0.763 0.03913 10 0.746 0.032 30 0.759 0.04014 16 0.749 0.037 38 0.753 0.03915 6 0.756 0.034 18 0.745 0.04016 15 0.740 0.032 35 0.750 0.03917 5 0.736 0.035 19 0.744 0.04618 5 0.726 0.033 17 0.731 0.033

J, jugale; Ag, antegonion; L, low angle; A, average angle; H, high angle.
*Statistically significant.
Table VII. Predicted ratio of J-J to Ag-Ag from regres-sion analysis of data in Table VI

Age

Predicted J-J/Ag-Ag


6 0.774 0.783 0.7687 0.771 0.780 0.7648 0.768 0.777 0.7609 0.765 0.774 0.756

10 0.762 0.771 0.75311 0.758 0.768 0.74912 0.755 0.765 0.74513 0.752 0.762 0.74214 0.749 0.759 0.73815 0.742 0.755 0.73816 0.735 0.750 0.73817 0.729 0.746 0.73818 0.722 0.741 0.738

The use of a ratio in a PA cephalometric study is



advantageous because the results can be compared withother subjects or groups whose radiographs have beentaken with uncontrolled enlargement of the variousskull structures on a x-ray film. The results of our studydemonstrate that the J-J/Ag-Ag ratios were smaller thanthe Rocky Mountain norms of Ricketts et al17 at allages. There is a general trend of ratio decrease fromages 6 to 18 in the low- and average-angle groups. Forthe high-angle group, the ratio decreased from ages 6 to14 and then a plateau was seen.

Our data clearly showed the significant differencesamong the high-, average-, and low-angle groups in thegrowth of J-J and Ag-Ag. This might indicate thatdifferent facial morphological patterns (short or longface) play a strong role in the growth and basicconfiguration of the maxillary and mandibular apicalbases as suggested by Enlow and Hans.1

CONCLUSIONS

The following conclusions can be made from thisstudy:

1. At age 6, the high-angle group had smaller maxil-lary (J-J) and mandibular (Ag-Ag) widths than thelow-angle group. This trend was consistent untilage 18 years.

2. Maxillary transverse growth (J-J) increased at asimilar rate of 0.90 to 0.95 mm per year from ages6 to 14 for all 3 groups. There was little or no moremaxillary transverse growth after age 14.

3. Mandibular transverse growth (Ag-Ag) increased ata steady rate (1.6 mm/year) for the low-, average-,and high-angle girls until age 14. A plateau at age14 was noted for the high-angle group, and contin-

Fig 5. Predicted ratio of J-J/Ag-Ag of low-, a

ued growth was seen in the low- and average-angle

groups until age 18 (0.85 mm and 0.39 mm peryear, respectively).

4. Vertical facial patterns (with low or high MP-SNangles) might play a strong role in the transversegrowth of the maxilla and the mandible.

We thank Drs Seong Han and Solomon Katz fortheir help.

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Editors of the International Journal of Orthodontia (1915-1918),International Journal of Orthodontia & Oral Surgery (1919-1921),International Journal of Orthodontia, Oral Surgery and Radiography (1922-1932),International Journal of Orthodontia and Dentistry of Children (1933-1935),International Journal of Orthodontics and Oral Surgery (1936-1937), AmericanJournal of Orthodontics and Oral Surgery (1938-1947), American Journal ofOrthodontics (1948-1986), and American Journal of Orthodontics and DentofacialOrthopedics (1986-present)

1915 to 1932 Martin Dewey1931 to 1968 H. C. Pollock1968 to 1978 B. F. Dewel1978 to 1985 Wayne G. Watson1985 to 2000 Thomas M. Graber2000 to present David L. Turpin

transverse growth of the maxilla and mandible in untreated girls with low, average, and high mp sn...

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