Occlusal contact changes after the active phase of orthodontic treatment B~ilent Haydar, DDS, MS," Semra Ciger, DDS, MS, PhD,b and Pinar Saat~:i, DDS, MS"

Ankara, Turkey Occlusal contacts in maximum intercuspidation were recorded at the end of active orthodontic treatment and 3 months into the retention period. Hawley retainer, tooth positioner, and nontreated normal occlusion groups of 10 subjects were examined for change in the number and location of occlusal contacts. Soft silicone-base impression materials were used to make interocclusal registrations. The contacts were then transferred onto the study models, and standard photographs of each model were taken. To determine any Iocational changes, superimposition of the first registration photograph on the second one was done. Significant difference in the number of total contacts between the treated groups and the control sample was recorded at both time periods. Use of a tooth positioner as a retainer did not show any additional gain of contacts in the positioner group when compared with the Hawley retainer group. No significant change in the location of contacts occurred during the period of observation. (AM J OnTHOD DENTOFACOFITHOP1992;102:22-28.)

O r t h o d o n t i c treatment objectives can be stated as obtaining functional occlusion aesthetics and stability at the end o f active treatment. One o f the criteria for obtaining a functional occlusion is to have stable centric stops on all teeth in maximal intercuspidation, t Changes in these contacts after the active phase of orthodontic therapy have been reported by various investigators. 24 Claims have been made on the advantage of using a tooth positioner appliance during the retention phase for rapid alignment and improvement of the interarch relationship, s'6 Comparison between conventional retainers and tooth positioners has also been made during the retention period, s Our study is aimed at solving two main questions: (I) How does the number o f occlusal contacts relate to the contacts found in normal occlusion at the completion of active orthodontic treatment and 3 months later? (2) Will there be any change o f location in the first 3month period in the number o f contacts that were present at the end o f treatment? These objectives were studied between the Hawley, positioner, and control groups.

MATERIALS AND METHODS Twenty patients who were treated in the postgraduate orthodontic clinic at the Hacenepe University, Faculty of Dentistry and 10 adolescents in a similar age group who had

From the Department of Orthodontics, ltacettepe University, Faculty of Dentistry, Ankara, Turkey. 'Research Assistant. ~Professor and Chairman. 8 / I / 28802

22

normal occlusions and did not receive treatment were taken into consideration (Table I). Of the 20 patients treated, 8 had Class I malocclusions, 10 had Class II, Division 1 malocclusions, and 2 had Class III malocclusion pretreatment. All patients were treated with full banded and/or bonded edgewise appliances to an optimum occlusion. The treatment patients were divided into two groups, l0 patients used upper and lower llawley retainers, and 10 patients used custom hinge-axis tooth positioners fabricated by a commercial laboratory (TP Orthodontics, La Pone, Ind.). }tawley retainers were worn on a full-time basis, tooth positioners were worn actively for 4 hours during the day plus 8 to 9 hours of sleeping time. Each of the treated groups covered five cases treated with four first premolar extractions and five nonextraction cases. Occlusal records were taken by a similar method described by Razdolsky~ and Durbin 3 within an hour after the removal of fixed appliances with Xsantopren (Bayer Dental, Leverkusen, Germany), a soft silicone-based impression material.7 To place the impression material on the occlusal surfaces properly, the tips of the 2 cc syringes were modified. Impression material was loaded into two separate syringes and then applied onto the lower occlusal surfaces of the patients who were then asked to bite it firmly with their back teeth for 30 seconds (Fig. 1). After a 15-minute rest, the procedure was carried out a second time to compare it with the first one for reproducibility, and if needed, a third registration would be taken that would confirm one of the two previous registrations. The interocclusal registration was then viewed by holding it to the daylight, perforations that let the light through were recorded as actual contacts, and very thin transparent sections without perforations were recorded as near contacts. After scoring these contacts, they were then transferred onto the upper cast. The midpoint of the near contact areas were used for marking onto the cast.

Occlusal contact after active phase of treatment

Volume102

Number I

23

p -

Fig. 1. Impression material applied onto lower right occlusal surface.

To observe any changes in the location of contacts, standard pictures of the occlusal view of the models were taken with the help of a setup that made it possible to standardize all the photographs taken (Fig. 2). Contacts on the first registration photograph were traced on acetate paper and superimposed on the second registration photograph for each tooth separately. For this procedure, actual and near contacts were used together, but only the contacts marked in the first registration that were also present in the second registration were taken into consideration. Migration of contacts toward the palatal cusp tip or the central fossa was not recorded in quantity, but was recorded as the number of changed contacts, either favorably or unfavorably. Unchanged contacts were not used for the statistical evaluation. The data were analyzed with the SYSTAT program package. T, describes the period when the first registration was taken, and "F2 describes the time 3 months later. The MannWhitney U test was performed to compare the groups for total contacts at T~ and T2. The Wilcoxon signed ranks test was performed to determine the longitudinal change of the groups studied. As well as the SYSTAT, the X2 test was used for determining any significant Iocational changes, and Fisher's exact • test was used when the expected frequency was less than 5.

FINDINGS Comparison of the groups for the total number of contacts at T, and T=

The mean total number of contacts at T~ for the Hawley (It), positioner (P) and control (C) groups were 21.20, 24.80, and 39.40, respectively. Comparison of the H and P groups with the C sample revealed a statistically important difference (p < 0.001 and p < 0.003, respectively), whereas no statistical differ-

Table I. Average ages at TI

Variables Hawley Positioner Control

I

"~ 16.15 14.42 15.16

I

SD 1.93 0.97 0.73

ence was found between the H and P groups (p > 0.05) (Table II). At Tz the mean number of contacts for the H, P, and C groups were found to be 22.40, 27.00, and 40.50, respectively. Comparison of the H and P groups with the C sample showed a statistically significant difference (p < 0.001 and p < 0.006, respectively), and again no statistical difference was found between the II and P groups (Table III). Longitudinal changes in actual and near contacts for the groups studied separately

In the Hawley group, actual contacts on the second premolars showed a decrease from a mean of 2.20 to 1.20, which was statistically significant (p < 0.05). No other variables in this group showed a statistically significant change (Table IV). In the positioner group, no statistically significant change was observed (Table V). In the control group, the mean number of near contacts on the second molars increased from 5.00 to 6.70, and the mean number of actual contacts on the first molars decreased from 6.50 to 4.50. These were the only variables in which a significant change was shown (p < 0.05 for both) (Table VI).

24

Haydar, Ci~er, and Saatfi

Am. J.

Orthod. DentofiTc.Ortkop. Ju/y 1992

of contacts are shown on Table IX (evaluated for the upper arch). DISCUSSION

Fig. 2. Setup to take standard photographs of occlusal surfaces of study casts with an adjustable plate to touch prepared plexiglass.

Changes in the location of contacts

No statistically significant difference was found in posterior contacts between the three groups studied. Similarly, no statistically significant difference was found in anterior contacts between the three groups studied (p > 0.05) (Tables VII and VIII). Location of contacts on the occlusal surfaces of teeth

Distribution of contacts on the occlusal surfaces for the H, P, and C groups were studied, and the mesiolingual cusps of the first and second molars were found to have the highest number of contacts compared with the total number of contacts. Details of the distribution

Evaluation of the number of occlusal contacts at the end of active orthodontic treatment has not been a routine procedure in orthodontic clinics. Examination of the interarch occlusal relationship intraorally or on a study cast does not properly reveal the number and the location of the occlusal contacts. In this study an effective and easy method has been used to evaluate the interarch relationship more precisely. Our method was shown to be reliable in previous studies. 3,4 The total mean number of contacts at the end of active treatment for the H and P groups was 21.20 and 24.80, respectively, which was much less than the normal-occlusion C group of 39.40. After a 3-month initial period, there was a slight increase in the H group to 22.40 and in the P group to 27.00. This is in accordance with previous studies and has been indicated by Durbin and Sadowsky 3 that the settling may continue up to 21 months. But this slight increase in our treatment groups was not found to be statistically significant when compared with our C group. Theoretically in ideal occlusions if a cusp tip contacts two opposing marginal ridges, two contacts on the cusp tip will result, or if it contacts only one opposing ridge, only one contact on the cusp tip will result. 8 If we extend this concept to the whole arch, we may have either 34 or 48 contacts in ideal occlusions or anything in between. Ricketts 9 reported 48 contacts in an ideal occlusion. Our findings in the normalocclusion group are similar to this finding with 40.50 • 9.68 contacts but contradicts the mean nuniber of 79 contacts reported by Ehrlich and Taicher. ~~ Gazit and Lieberman 2 reported a total number of 11.2 contacts at the end of treatment and 17.4 after a year with the photoocclusion technique. Durbin and Sadowsky 3 using the same method as ours, had recorded 10.11 contacts at the end of treatment and 11.53 contacts after 3 months. In their study only the actual contacts were recorded, and this may explain the low number of contacts. Razdolsky et al.4 counted a mean number of 36.6 contacts at the end of treatment and 58.2 contacts after 21 months. An interesting finding in our control group was an increase in the number of near contacts on second molars and a decrease in the number of actual contacts on first molars. Although this change had occurred over a short period of 3 months, this may be explained by the continued eruption of the second molars into a tighter occlusal relationship thus relieving the occlusal forces

Volume 102 NIvnber I

Occlusal contact after active pllase (~ treatment

25

Table II. Comparison of total contacts at the end of treatment between the three groups studied contacts

7"1mean

SD

21.20 39.40 24.80 39.40 21.20 24.80

5.59 9.87 5.79 9.87 5.59 5.79

Hawley Control Positioner Control tlawley Positioner

u

p value

6

0.001"**

!1

0.003**

34

0.225

**p < 0.01. ***p < 0.001.

Table Ill. Comparison of total contacts at 3 months into retention period between the three groups studied Total nunlber of contacts

[

] Tz nlean

SD

22.40 40.50 27.00 40.50 22.40 27.00

7.07 9.68 8.56 9.68 7.07 8.56

Hawley Control Positioner Control tlawley Positioner

n

p Va[lte

7

0.001"**

14

0.006**

32

0.171

**p < 0.0l. ***p < 0.1301.

Table IV. Longitudinal changes of occlusal contacts for the Hawley group Variables

AC NC AC NC AC NC AC NC AC NC AC NC

second molars second molars first molars first molars second premolars second premolars first premolars first premolars canines canines incisors incisors

AC, Actual contacts;

Mea. (T3

Mean (Tz)

3.50 2.90 3.30 2.70 2.20 1.60

3.60 3.20 3.40 3.40 1.20 2.30 0.80 0.60 0.10 1.80 0.60 1.80

1.00 1.00 0.20 I. 10 0.10 1.60

I

I

[

Difference (T2-Td 0.1 0.3 0.1 0.7 - ! .0 0.7 -0.2 -0.4 - 0.1 0.7 0.5 0.2

SD (T2-TI)

p value

1.370 1.251 2.424 1.702 1.054 1.337 0.699 0.843 0.316 1.337 0.707 2.097

0.889 0.463 0.447 0.214 0.030* 0.151 0.109 0.178 0.317 0.138 0.068 0.726

NC, near contacts.

*p < 0.05.

from the first molars farther back, resulting in a decrease of contacts in this area. In a previous study, the highest percentage of contacts were found to be on the upper first molars? ~ In our study the upper first molar region was also found to contain the highest number of contacts, and in addition, the mesiolingual cusp of the upper first molar was found to be an important area containing an average

of 4 _ 2.45 contacts at T, and 3.8 _+ 2.09 contacts at Z2. No significant difference was found with custom hinge-axis tooth positioners compared with Hawley retainers in the first 3-month period. Although Durbin and Sadowsky 3 found the tooth positioner to be statistically more effective than the conventional retainer, they mention that there was a greater percentage of

26

Haydar, Ci~,er, attd Saatfi

Am. J. Orthod.Dentofac.Orthop. July 1992

Table V. L o n g i t u d i n a l c h a n g e s o f o c c l u s a l c o n t a c t s for the p o s i t i o n e r g r o u p

I

Variables

Mean (TI)

AC second molars NC second molars AC first molars NC first molars AC second premolars NC second premolars AC first premolars NC first premolars AC canines NC canines AC incisors NC incisors

AC, Actual contacts; NC,

I

Mean (T~)

4.60 4.40 3.70 3.50 1.50 2.20 0.80 0.30 1.10 I. 10 0.60 2.40

3.60 5.00 2.50 4.80 0.90 1.90 0.30 0.50 1.40 1.30 1.50 3.00

Difference (T2-TI) - 1.0 0.6 - 1.2 1.3 -0.6 - 0.3 -0.5 0.2 0.3 0.2 0.9 0.6

SD (7"2-7"1)

p value

2.309 1.955 2.149 2.451 1.264 1.251 0.971 0.788 0.483 1.619 2.424 2.412

0.193 0.333 0.123 0.128 0.176 0.463 0.109 0.423 0.109 0.678 0.281 0.343

near contacts.

Table VI. L o n g i t u d i n a l c h a n g e s o f o c c l u s a l c o n t a c t s for the c o n t r o l g r o u p

I

Variables AC second molars NC second molars AC first molars NC first molars AC second premolars NC second premolars AC first premolars NC first premolars AC canines NC canines AC incisors NC incisors

Mean iT,)

I

Mean (T2) 4.70 6.70 4.50 7.50 2.30 3.10 2.10 2.00 0.40 2.40 1.30 3.20

5.00 5.00 6.50 6.00 2.20 3.90 1.50 3.10 0.80 1.90 1.00 2.70

Difference (T2"TI)

SD (T2"TI)

-0.3 1.7 - 2.0 i .5 0.1 -0.8 0.6 - I. I - 0.4 0.5 0.3 0.5

I

p value

1.418 1.813 2.708 3.439 1.370 i.135 1.337 1.595 1.178 !.080 0.674 1.080

0.612 0.028* 0.043* 0.173 0.917 0.068 0.208 0.080 0.345 0.178 0.180 0.178

*p < 0.05.

AC, Actual contacts; NC,

near contacts.

Table VII. C h a n g e s in l o c a t i o n o f p o s t e r i o r

Table VIII. C h a n g e s in l o c a t i o n o f a n t e r i o r

occlusal contacts (Actual and near contacts combined)

o c c l u s a l c o n t a c t s (actual a n d n e a r c o n t a c t s c o m b i n e d ; F i s h e r ' s e x a c t X 2 test w a s u s e d )

Variable

Number of changed contacts

ttawley Positioner Hawley Control Positioner Control

53 49 53 60 49 60

X2

p value

Variables

2.98

0.()7

1.09

0.09

0.58

0.14

Hawley Positioner Hawley Control Positioner Control

n o n e x t r a c t i o n c a s e s in the p o s i t i o n e r g r o u p , w h i c h c o u l d h a v e m a d e the slight d i f f e r e n c e . In o u r s a m p l e , t h e r e w a s a n e q u a l n u m b e r o f ext r a c t i o n a n d n o n e x t r a c t i o n c a s e s in the t r e a t m e n t

I

Number of changed contacts 8 14 8 8 14 8

I

p value 0.88 0.50 0.71

g r o u p s . T h i s m a y partially b e r e s p o n s i b l e for the l o w m e a n n u m b e r o f c o n t a c t s in the t r e a t m e n t g r o u p s w h e n c o m p a r e d w i t h the c o n t r o l s a m p l e . E n l a r g i n g the treatm e n t g r o u p s in a future s t u d y m a y rule out this bias.

Volume 102 Number I

Occhtsal contact t~er active phase of treatment 2 7

T a b l e IX. L o c a t i o n o f contacts on the occlusal surfaces o f teeth

ltawley

Positioner

Control

TI

T2

1",

T~

Tt

Mean I SD

Mean I SD

Mean ] SD

Mean ] SD

Mean [ SD

Mean I SD .

Second molars Mesial and distal marginal ridge Mesiolingual cusp Distolingual cusp Inner inclination of MB cusp Inner inclination of DB cusp Oblique ridge

1.5 3.3 0.4 0.7 0.2 0.2

1.08 2.54 0.52 0.68 0.42 0.63

1.2 3.7 0.2 0.6 0.1 0.2

0.63 3.20 0.,~2 0.69 0.32 0.63

I.I 2.4 0.3 1.4 0.4 0.2

1.10 2.41 0.68 1.27 0.84 0.42

0.8 3.0 0.4 1.3 0.4 0.2

0.79 1.76 0.69 1.25 0.69 0.42

1.8 3.8 0.5 I.I 1.9 0.4

0.92 2.15 0.71 0.99 0.94 0.70

!.8 4.5 0.6 1.4 0.9 0.6

1.14 2.72 0.69 0.84 0.88 0.71

1.6 2.1 1.4 1.0 0.4 0.2

1.35 1.29 1.08 0.67 0.52 0.63

1.4 2.3 1.9 0.7 0.4 0.2

0.69 1.34 1.59 1.06 0.52 0.42

2.4 2.1 0.8 1.6 0.9 0.4

0.84 1.59 0.92 1.08 I. 10 0.71

1.8 2. I 1.1 i .3 0.9 0.5

1.14 0.74 1.29 0.82 1.10 0.71

2.7 4.0 3.4 1.2 0.9 0.8

0.95 2.45 1.51 0.92 0.74 0.79

2.5 3.8 3.5 1.0 0.7 0.9

0.97 2.09 1.44 0.94 0.68 0.88

1.3 1.6 0.6

0.82 1.08 0.52

1.8 1.4 0.7

0.92 1.17 0.68

1.4 1.8 1.0

0.91 1.14 0.94

i.4 !.7 0.8

1.26 1.16 I. 14

2.1 2.5 1.4

0.99 1.51 1.51

2.0 2.6 1.2

1.05 1.43 1.23

0.5 1.2 0.4

0.85 !.81 0.52

0.2 0.7 0.3

0.42 1.25 0.48

0.5 0.4 0.2

0.97 0.97 0.63

0.5 0.5 0.1

1.08 0.85 0.32

2.2 1.2 1.2

1.23 1.39 0.92

2.2 1.1 1.1

1.14 i.19 0.87

1. I 0.3

0.57 0.68

1.2 0.3

0.63 0.68

1.7 0.4

1.49 0.84

1.7 0.5

0.75 0.71

1.4

1.27

1.7

1.25

0.6

0.84

0.7

0.94

1.3 0. I

0.79 0.32

2.7 0.2

1.83 0.42

3.0 0.5

1.56 0.97

4.1 1.4

2.33 1.35

4.0 1.0

2.45 0.82

3.8 1.7

2.25 1.63

First molars Mesial and distal marginal ridge Mesiolingual cusp Distolingual cusp Inner inclination of MB cusp Inner inclination of DB cusp Oblique ridge

Second premolars Mesial and distal marginal ridge Lingual cusp Inner inclination of buccal cusp

First premolars Mesial and distal marginal ridge Lingual cusp Inner inclination of buccal cusp

Canhzes Mesial and distal marginal ridge Lingual ridge

Incisors Mesial and distal marginal ridge Lingual fossa

MB, Mesiobuccal; DB, distobuccal.

N o significant c h a n g e in the location o f contacts was found in the anterior and posterior sections after the initial 3-month period. This agrees with the finding o f a previous study that the majority o f the contacts did not c h a n g e from the time o f appliance r e m o v a l . 4

SUMMARY AND CONCLUSIONS 1. At the end o f active orthodontic treatment and 3 months later, no difference was found b e t w e e n the H a w l e y and the positioner groups when the total contacts w e r e c o m p a r e d , but an important difference was found w h e n these groups were c o m p a r e d with the control sample. 2. In the initial 3 - m o n t h retention period, no difference could be found b e t w e e n tooth positioner and a H a w l e y retainer from the aspect o f gainin'g m o r e occlusal contacts. 3. During the t i m e period o b s e r v e d , s o m e occlusal

changes w e r e recorded in the control sample that i m p l y that occlusal contact changes should be e x p e c t e d in g r o w i n g patients. 4. N o significant change in the location o f contacts occurred w h e n the three groups w e r e c o m p a r e d during the period o b s e r v e d . A f t e r the end o f active orthodontic therapy, although s o m e slight changes occur, no important change in the n u m b e r and the location o f occlusal contacts should be expected. In this respect a final occlusion, which is as ideal as possible, should be reached by the end o f orthodontic therapy, and o n l y m i n i m a l changes should be left to o c c u r during the retention period. We are grateful to Dr. Ata Aksoy for valuable advice and for carrying out the statistical analysis.

REFERENCES I. Dawson PE. Evaluation, diagnosis and treatment of occlusal problems. St. Louis: CV Mosby, 1974:293-300.

28

Am. J. Orthod. Dentofac. Orthop. July 1992

Haydar, Ci~er, and Saatqi

2. Gazit E, Lieberman MA. Occlusal contacts following orthodontic treatment: measured by a photoocclusion technique. Angle Orthod 1985;55:316-20. 3. Durbin DS, Sadowsky C. Changes in tooth contacts following orthodontic treatment. AM J ORTHOD DENTOFAC ORTttOP 1986;90:375-82. 4. Razdolsky Y, Sadowsky C, BeGole EA. Occlusal contacts following orthodontic treatment: a follow up study. Angle Orthod 1989;59:18 I-5. 5. Kesling HD. The philosophy of the tooth positioning appliance. AM J ORTHOD 1945;31:297-304. 6. Bemett JW. The centric relation tooth positioner: its use as a finishing appliance for modem orthodontics. J Clin Orthod 1978; 12:24-37. 7. Battistuzzi PGFCM, Eschen S, Peer PGM. Contacts in maximal occlusion. J Oral Rehabil 1982;9:499-507.

8. Okeson JP. Management of temporomandibular disorders and occlusion. St Louis: CV Mosby, 1989:59-86. 9. Ricketts RM. Occlusion in medium of dentistry. J Prosthet Dent 1969;21:39-57. 10. Ehrlich J, Taicher S. Intercuspal contacts of the natural dentition in centric occlusion. J Prosthet Dent 1981;45:419-21.

Reprhzt requests to: Dr. Bfilent Haydar Department of Orthodontics Faculty of Dentistry University of Hacettepe 06100 Ankara Turkey

AAO MEETING CALENDAR

1993--Toronto, Canada, May 15 to 19, Metropolitan Toronto Convention Center 1994--Orlando, Fla., May 1 to 4, Orange County Convention and Civic Center 1995--San Francisco, Calif., May 7 to 10, Moscone Convention Center

(Intemationa/ Orthodontic Congress) 1996--Denver, Colo., May 12 to 16, Colorado Convention Center 1997mPhiladelphia, Pa., May 3 to 7, Philadelphia Convention Center 1998--Dallas, Texas, May 16 to 20, Dallas Convention Center 1999--San Diego, Calif., May 15 to 19, San Diego Convention Center

Occlusal contact changes after the active phase of orthodontic treatment.

Occlusal contacts in maximum intercuspidation were recorded at the end of active orthodontic treatment and 3 months into the retention period. Hawley ...
1MB Sizes 0 Downloads 0 Views