Accuracy of

a lingual indirect bonding system using a 3D virtual program

Hye-Young Choi

The Graduate School Yonsei University

Department of Dental Science

Accuracy of

a lingual indirect bonding system

using a 3D virtual program

Directed by Professor JUNG-YUL CHA

The Master’s Thesis

Submitted to the Department of Dental Science

and the Graduate School of Yonsei University

in partial fulfillment of the requirements for the degree of

Master of Dental Science

HYE-YOUNG CHOI

June 2011

This certifies that the dissertation of

HYE-YOUNG CHOI is approved.

Thesis supervisor

The Graduate School

Yonsei University

June 2011

감사의 글

부족한 저를 이끌어 주시고 논문의 시작부터 완성되기까지 따뜻한 배려와

가름침으로 이끌어 주신 차정열 지도 교수님께 진심으로 감사드리며, 바쁘신

와중에도 많은 관심과 조언으로 부족한 논문을 세심하게 살펴주신 황충주

교수님과 유형석 교수님께 깊이 감사드립니다. 또한 3년간의 수련기간 동안

교정학뿐만 아니라 삶에 대해 많은 가르침을 주시고 보살펴 주신 박영철 교수님,

백형선 교수님, 김경호 교수님, 이기준 교수님, 정주령 교수님, 최윤정 교수님께도

감사드립니다.

의국 생활 동안 많은 도움을 주시고 큰 힘이 되어주셨던 의국 선배님들과

후배님들, 직원분들께 감사드리며 특히 많은 어려움을 함께한 의국 동기 김철순,

시경근, 최성환, 최윤희와 의국 후배 유성훈, 뭉해도람, 배미주 선생에게 이

자리를 빌려 감사의 마음을 전합니다.

마지막으로 항상 변함없는 사랑으로 돌봐주시고 모든 일을 전폭적으로

지원해주시는 부모님과 가족들께 감사드리며 늘 곁에서 응원해주는 사랑하는

남편에게 감사의 마음을 전합니다.

2011년 6월 저자 씀

i

Table of contents

List of tables ······························································································· ii

List of figures ····························································································· iii

ABSTRACT ······························································································ iv

I. INTRODUCTION ····················································································· 1

II. MATERIALS AND METHODS ···································································· 5

A. Inclusion criteria ·················································································· 5

B. Methods ···························································································· 5

C. Statistical analysis ················································································ 8

III. RESULTS ···························································································· 13

IV. DISCUSSION ······················································································· 19

V. CONCLUSION ······················································································· 23

REFERENCES

ii

List of tables

Table 1. Mean of virtual and actual torque and mean & standard deviation of absolute torque

errors ···························································································· 14

Table 2. Mean of virtual and actual depth and mean & standard deviation of absolute depth

errors (resin base thickness) ································································· 15

Table 3. Mean of virtual and actual tip and mean & standard deviation of absolute tip errors ····· 16

Table 4. Mean of virtual and actual height and mean & standard deviation of absolute height

errors ···························································································· 17

Table 5. Comparison of the absolute mean errors of all variables between the 2-piece jig group

(incisors, canines, and second premolars) and 1-piece jig group (first and second

molars)·························································································· 18

Table 6. Mean and standard deviation of absolute torque, depth, tip and height errors ········· 18

iii

List of figures

Fig. 1. Virtual setup and bracket positioning

A. Digitization of the model

B. Segmentation and Normalization

C. Virtual setup

D. Checking for occlusal contact

E. Virtual bracket positioning

F. Customized wire ·············································································· 9

Fig. 2. Transfer jigs and indirect bonding procedure

A. 2-piece and 1-piece transfer jigs

B. Adaptation of the transfer jig for fabrication of the bracket resin base

C. Silicone transfer trays

D. Brackets bonded to the initial model

E. Silicone rubber impressions

F. Fabrication of the hard plaster model

G. 3Txer virtual bracket bonding data

H. Superimposition of virtual and actual bracket bonding data ··························· 10

Fig. 3. Measurement of torque errors ·································································· 11

Fig. 4. Measurement of depth errors (resin base thickness) ········································ 11

Fig. 5. Measurement of tip errors ······································································ 12

Fig. 6. Measurement of height errors ·································································· 12

iv

ABSTRACT

Accuracy of a lingual indirect bonding system

using a 3D virtual program

Recently, 3D virtual setup program, a highly advanced computer-driven system has been

used in indirect bonding, enabling customized patient treatment. It can decrease the number of

steps in the existing manual setup used for indirect bonding, saving laboratory time. In

addition, individual jigs for indirect bonding can be manufactured by the 3D virtual program

based on the virtual setup model. However, it is unclear if this new system is more accurate

than conventional methods because only a few studies have evaluated the accuracy of such

cutting-edge bracket bonding techniques.

We aimed to evaluate the accuracy of bracket placement for lingual indirect bonding

techniques when a 3D virtual setup system (3TxerTM; Orapix, Seoul, Korea) is used in vitro.

Four variables—torque, depth, tip, and height—were measured in order to evaluate the

difference between virtual and actual bracket positions. A 3D program (Rapidform 2006TM;

Inus Technology, Seoul, Korea) via a superimposition process was used for this purpose. The

results of this study were as follows.

v

1. All variables showed significant differences between the virtual and actual bracket positions

(P < 0.001).

2. The mean values of the absolute torque, depth, tip, and height error were 4.84° ± 3.33°, 0.33

mm ± 0.22 mm, 1.39° ± 1.05°, and 0.35 mm ± 0.27 mm, respectively.

3. For all variables, the difference between the right and left and the maxilla and mandible was

not significant.

4. There was significant difference in torque between the 2-piece jig group (incisors, canines,

and second premolars) and 1-piece jig group (first and second molars) (P < 0.001).

Errors might occur during fabrication of the customized resin base or silicone transfer trays

because these processes are executed manually. Therefore, control of manual laboratory

procedures is a key factor for successful virtual indirect bonding along with the accuracy of

digitations of plaster models. Clinically, in the final stage of treatment, wire bending, re-setup

of the models, or re-bonding of the brackets may be required. Further studies are needed to

improve the virtual indirect bonding system discussed in this study.

Key words: 3D virtual program, lingual orthodontics, indirect bonding method, bracket

positioning

1

Accuracy of a lingual indirect bonding system using a 3D virtual program

HYE-YOUNG CHOI, D. D. S.

Department of Dental Science

Graduate School of Yonsei University

(Directed by Prof. JUNG-YUL CHA, D. D. S., M.S.D., Ph. D.)

I. Introduction

Precise bracket bonding is essential for improving the final outcomes of orthodontic

treatment. There are two bonding methods: a direct and an indirect method. Some authors

report no difference between these methods in terms of accuracy and bonding strength

(Hocevar and Vincent, 1988; Hodge et al., 2001; Milne et al., 1989). However, the indirect

bonding method has many advantages such as patient comfort, facility to rebond brackets,

overcorrection, in/out control, and reduced use of staff and chair time (Kalange, 2004). In

lingual orthodontics, in particular, the indirect bonding technique is useful because it is better

for working with an irregular lingual surface with limited access, short clinical crown length,

sloped lingual surface, and tongue interference, all of which contribute to inaccurate bracket

bonding (Geron, 1999).

2

Laboratory techniques for the indirect bonding method have been developed over the past

30 years. Sondhi (1999) reported a new indirect bonding method using a transfer tray with

BioplastTM and Transbond XT, and some researchers use a silicone transfer tray with a

chemical curing resin (Sondhi, 1999). Recently, highly advanced computer-driven systems

have been developed for indirect bonding, enabling customized patient treatment. SureSmile®

(Orametrix, Inc., Richardson TX) is one such system; it captures vivo images of the dentition

in real time, and the images are then manipulated in a 3D digital diagnostic setup (Muller-

Hartwich et al., 2007; Sachdeva et al., 2005). In a technology system similar to OrthoCAD®

(Cadent, Inc., Carlstadt, NJ), plaster models are sent to a processing department, and

stereolithography is used to create a digital model. From these digital models, bracket

positioning can be established using a pen-sized wand, a miniature video camera, and LEDs

that enable the virtual setup (Redmond et al., 2004). For example, Mujagic and coworkers

(2005) created custom gold alloy lingual brackets that were indirectly bonded with the

Lingualcare® (Lingualcare Inc., Dallas, TX) system.

Computerized 3D virtual models are currently available and used to calculate many

diagnostic measurements. Digital models can solve many problems and difficulties associated

3

with the storage, retrieval, reproduction, communication, and breakage of conventional plaster

casts. The accuracy of digital models is acknowledged by many authors, and these models are

used to assess the American Board of Orthodontics objective grading system (ABO OGS).

There is also no significant difference in measurements of the overjet, overbite, space analysis,

and the Bolton ratio obtained by digital models and those obtained using plaster casts (Leifert

et al., 2009; Okunami et al., 2007; Santoro et al., 2003).

In addition, virtual setup and bracket positioning can be incorporated into the indirect

bonding method using digital models. For example, the InsigniaTM system (Ormco, CA) uses

the CAD/CAM program and 3D ApproverTM (Cadent, Inc., Carlstadt, NJ) program, which

enables individual tooth setup and produces customized brackets and wires.

Recently, a new 3D dental scanning and virtual setup program was developed (3TxerTM;

Orapix, Seoul, Korea). Fabricated dental casts are scanned with a 3D dental laser scanner, and

3D analysis of digital models is performed using the 3DxerTM program. 3TxerTM enables 3D

virtual setup according to a treatment plan. It can reduce the stages of existing manual setup

for indirect bonding, reducing laboratory time. In addition, individual jigs for indirect bonding

can be manufactured by the 3D virtual program based on virtual setup models. Recently, this

4

3D virtual setup system has begun to be used in lingual orthodontics. However, it is unclear if

this new system is more accurate than the conventional methods for bracket positioning

because only a few studies have evaluated the accuracy of such cutting-edge bracket bonding

techniques.

We aimed to evaluate the accuracy of bracket placement for lingual indirect bonding

techniques using a 3D virtual setup system in vitro.

5

II. Materials and Methods

1. Inclusion criteria

The sample consisted of 5 patients who needed their upper and lower first premolars

extracted because of mild crowding and dental protrusion. None had tooth size discrepancy,

congenital missing teeth, or abnormalities of the lingual surface. All teeth were bonded with a

lingual appliance, Clippy L® (Tomy, Fukushima, Japan).

2. Methods (Fillion, 2010; Fillon, 2007)

1) Laser scanning of plaster models (Fig. 1, A)

Plaster models were first scanned with an Orapix scanner at a precision level of ±20

microns. The data from the scanner was used to visualize the 3D images. Scanning conditions

and occlusion of digital models were checked by clinicians.

2) Analysis and treatment planning

Model analysis, including tooth measuring, space analysis, and calculation of the Bolton

index was performed with the 3DxerTM program. A treatment plan was established by using

6

this mode of analysis, x-rays, and other diagnostic tools. Teeth to be extracted, anchor type,

and amount of stripping were decided in this step.

3) Segmentation and normalization of individual teeth (Fig. 1, B)

The dental arch was sectioned into individual dental units, and the axes of each dental unit

were determined using the normalization procedure.

4) 3D virtual setup and bracket positioning (Fig. 1, C–E)

First, the arch form was selected and modified for individual dental arches. Selected teeth

were extracted, and the anterior and posterior teeth were moved along with the selected wire.

Automatic alignment and group movement of teeth is possible in this program. After this

automatic procedure, the teeth were manually adjusted in all directions so that they were in the

final desired position. Finally, occlusion was checked from the posterior view, and the

collision test can be used in this step. The lingual appliance was selected, and bracket

positioning was automatically performed with the 3TxerTM program. Contact points of the

brackets with the surface of the teeth and opposing teeth were adjusted manually.

7

5) Construction of individual jigs and silicone transfer trays. (Fig. 2, A–C)

The Rapid-Prototype-Machine was used to construct individual jigs with resin for

transferring the brackets. The jigs were constructed in 2 parts, and they were bonded to a

plaster model to make an individual bracket resin base. For the posterior teeth, a tube is

usually used for posterior bonding; therefore, posterior jigs were designed using an

intervening wire in order to engage the tube. Silicone transfer trays (Heat-molten polymer of

ethylene vinyl acetate) were made for transferring the brackets to the mouth.

6) Indirect bonding procedure (Fig. 2, D–F)

Lingual brackets were bonded to the plaster initial models with sealant resin (Excel®). The

impression was taken off the plaster models with silicone rubber impression material divided

into 3 pieces. Hard plaster models were fabricated, and bracket slots or undercuts were

removed. The models were scanned with a laser scanner.

7) Superimposition of actual and virtual bracket positioning (Fig. 2, G–H)

Virtual and actual bracket positions were superimposed according to the tooth surface, and

8

the difference between them was measured based on that bracket base. The differences in 4

variables (torque, depth, tip, and height) between virtual and actual bracket positions were

measured with Rapidform 2006® (Inus Technology, Seoul, Korea) (Fig. 3–6). Each difference

was considered as the error of the bracket position. To evaluate the reliability and

reproducibility of the experiment, the 4 variables were measured twice for one sample at 2-

week intervals.

3. Statistical Analysis

SPSS software (version 12.0, SPSS, Chicago, III) was used for statistical analysis. To assess

measurement reliability, the intraclass correlation coefficient (ICC) was computed for each

measured variable. Means and standard deviations of the difference between the virtual and

actual bonded bracket positions were calculated. These differences were considered errors of

torque, depth, tip, and height. The data were analyzed with a paired t-test, one-way ANOVA,

and a Scheffe test at the .05 level of significance.

9

Fig. 1. Virtual setup and bracket positioning.

(A) Digitization of the model, (B) Segmentation and Normalization, (C) Virtual setup,

(D) Checking for occlusal contact, (E) Virtual bracket positioning, and (F) Customized

wire.

A

C

B

E

D

F E

10

Fig. 2. Transfer jigs and indirect bonding procedure.

(A) 2-piece (left) and 1-piece (right) transfer jigs. (B) Adaptation of the transfer jig for

fabrication of the bracket resin base. (C) Silicone transfer trays. (D) Brackets bonded to

the initial model. (E) Silicone rubber impressions. (F) Fabrication of the hard plaster

model. (G) 3Txer virtual bracket bonding data. (H) Superimposition of virtual and

actual bracket bonding data.

A

C

B

D

FE

G H

11

Fig. 3. Measurement of torque errors. Torque errors measure angles between the

reference plane of a virtual bracket base and the reference plane of the actual bracket

base; blue color, 3Txer virtual bracket data (virtual bonding); green color, model scan

data (actual bonding).

Fig. 4. Measurement of depth errors (resin base thickness). Depth errors measure the

distance from the center of the virtual bracket base (upper part) to the center of the

actual bracket base (upper part).

12

Fig. 5. Measurement of tip errors. Tip errors measure angles between the reference

vector on the upper margin of the virtual bracket base and that of the actual bracket

base.

Fig. 6. Measurement of height errors. Height errors measure the distance from the upper

margin of the virtual bracket base to that of the actual bracket base.

13

III. RESULTS

Intraclass correlation ranged from r = 0.85 to 0.99 (P < .001). Measurements of all variables

were highly reliable.

The largest absolute torque error occurred in the maxillary first molar area (6.57° ± 2.99°),

and the mean of torque errors was 4.84° ± 3.33°. The greatest absolute depth (resin base

thickness) error occurred in the mandibular second premolar area (0.65 mm ± 0.03 mm), and

the mean of depth errors was 0.33 mm ± 0.22 mm. The largest tip error occurred in the

maxillary canine area (2.45° ± 0.64°), and the mean was 1.39° ± 1.05°. The greatest absolute

height error was in the mandibular lateral incisor area (0.43 mm ± 0.08 mm), and the mean

was 0.35 mm ± 0.27 mm (Tables 1–4.). All variables were significantly different between the

virtual and actual bracket bonded positions (P < .001).

There was no significant difference between the right and left and the maxilla and mandible

for all variables but there was significant difference in torque according to jig types (P <

0.001). The 2-piece jig (incisors, canines, and second premolars) and the 1-piece jig group

(first and second molars) showed significant difference in torque (P < 0.001) (Table 5.).

14

Table 1. Mean of virtual and actual torque and mean & standard deviation of absolute

torque errors (°)

Right Left

Position

Virtual

torque

Actual

torque

Torque

errors

Virtual

torque

Actual

torque

Torque

errors

Mx. Central 4.07 7.72 3.65±3.08 6.36 8.16 3.04±1.53

Lateral 1.08 1.64 3.14±1.31 2.95 5.61 3.07±2.69

Canine -1.52 -2.71 3.86±1.81 -2.53 -1.14 2.79±1.75

Second premolar -2.21 0.47 4.87±2.37 -2.70 -0.63 3.87±3.24

First molar -7.89 -6.55 6.57±2.99 -6.71 -5.28 4.71±2.23

Second molar -8.48 -4.58 5.45±2.40 -8.82 -5.72 5.41±2.69

Mn. Central 2.31 4.28 3.67±2.74 1.17 4.50 3.95±1.96

Lateral 2.03 6.56 4.53±2.18 2.28 3.50 2.26±0.88

Canine -4.35 -1.31 3.71±2.24 -3.36 1.85 4.44±2.69

Second premolar -18.08 -3.80 4.47±1.99 -19.73 -9.08 3.87±3.37

First molar -19.72 -13.91 4.22±2.96 -17.42 -12.11 4.25±3.23

Second molar -25.24 -25.89 5.26±2.55 -20.97 -18.26 4.13±1.45

15

Table 2. Mean of virtual and actual depth and mean & standard deviation of absolute

depth errors (resin base thickness) (mm)

Right Left

Position

Virtual

depth

Actual

depth

Depth

errors

Virtual

depth

Actual

depth

Depth

errors

Mx. Central 1.03 1.37 0.29±0.18 1.09 1.27 0.18±0.20

Lateral 0.93 1.16 0.23±0.16 1.05 1.36 0.30±0.12

Canine 0.65 0.90 0.26±0.18 0.67 0.98 0.23±0.09

Second premolar 0.89 1.41 0.48±0.00 1.09 1.59 0.26±0.03

First molar 0.67 0.88 0.20±0.19 0.69 0.92 0.22±0.22

Second molar 0.74 1.08 0.26±0.20 0.71 0.98 0.27±0.12

Mn. Central 0.66 0.82 0.37±0.07 0.60 0.95 0.35±0.19

Lateral 0.47 0.74 0.26±0.15 0.60 0.73 0.32±0.10

Canine 0.63 0.95 0.32±0.19 0.52 0.78 0.26±0.13

Second premolar 0.74 1.15 0.62±0.01 0.69 1.11 0.65±0.03

First molar 0.72 0.88 0.16±0.12 0.75 1.04 0.29±0.14

Second molar 0.71 0.93 0.29±0.16 0.74 0.97 0.14±0.12

16

Table 3. Mean of virtual and actual tip and mean & standard deviation of absolute tip

errors (°)

Right Left

Position

Virtual

tip

Actual

tip

Tip

errors

Virtual

tip

Actual

tip

Tip

errors

Mx. Central -0.92 0.44 1.36±1.00 -0.78 -1.00 1.12±1.01

Lateral 0.79 0.88 1.27±0.62 0.01 0.24 1.38±1.08

Canine 0.74 0.36 2.45±0.64 -0.78 -0.17 0.61±0.46

Second premolar -2.58 -0.79 1.37±0.98 -2.53 -0.98 1.27±0.85

First molar -0.54 0.03 1.06±0.88 -1.75 -0.88 1.55±0.71

Second molar -0.74 -1.37 1.05±0.62 -2.12 -1.18 0.94±0.46

Mn. Central 0.64 1.75 1.54±0.79 -0.20 0.20 1.01±0.57

Lateral 0.85 1.79 0.94±0.41 1.57 0.76 1.63±0.34

Canine 1.86 1.35 0.93±0.37 2.97 3.49 1.36±0.56

Second premolar -0.34 1.08 0.91±0.46 3.22 2.82 1.36±0.81

First molar 4.62 4.68 1.08±0.83 2.92 2.88 0.61±0.36

Second molar 2.83 2.36 0.95±0.88 2.66 2.00 1.00±0.58

17

Table 4. Mean of virtual and actual height and mean & standard deviation of absolute

height errors (mm)

Right Left

Position

Virtual

height

Actual

height

Height

errors

Virtual

height

Actual

height

Height

errors

Mx. Central 3.37 3.16 0.11±0.07 3.43 3.25 0.18±0.15

Lateral 3.10 2.86 0.23±0.08 3.07 2.80 0.17±0.07

Canine 3.31 2.77 0.39±0.11 3.23 2.69 0.32±0.13

Second premolar 2.29 1.53 0.21±0.03 2.84 2.03 0.25±0.13

First molar 3.87 3.51 0.24±0.14 4.28 3.95 0.10±0.17

Second molar 3.66 3.40 0.26±0.12 3.85 3.32 0.26±0.12

Mn. Central 3.00 2.08 0.40±0.11 3.11 2.68 0.34±0.22

Lateral 3.15 2.69 0.26±0.11 3.16 2.19 0.43±0.08

Canine 3.53 3.01 0.41±0.14 3.55 3.14 0.40±0.04

Second premolar 3.03 2.33 0.12±0.09 2.66 1.90 0.28±0.18

First molar 2.67 2.40 0.27±0.10 2.16 1.91 0.24±0.11

Second molar 2.96 2.05 0.22±0.05 2.65 2.30 0.24±0.08

18

Tale 5. Comparison of absolute mean errors of all variables between 2-piece jig group

(incisors, canines and second premolars) and 1-piece jig group (first and second molars)

variables Errors of

2-piece jig group

Errors of

1-piece jig group P

Torque( °) 3.72±2.20 6.60±4.02 0.0002***

Depth(mm) 0.38±0.22 0.25±0.18 0.0032**

Tip( °) 1.48±1.09 1.20±0.94 0.1679

Height(mm) 0.36±0.26 0.33±0.29 0.4943

* *significance at the 0.01 level, *** significance at the 0.001 level

Tale 6. Mean and standard deviation of absolute torque, depth, tip and height errors

variables Mean SD

Torque( °) 4.84 3.33

Depth(mm) 0.33 0.22

Tip( °) 1.39 1.05

Height(mm) 0.35 0.27

19

. DISCUSSIONⅣ

All variables showed significant differences between virtual and actual bracket positions (P

< 0.001), which suggested inaccuracy of the virtual indirect bonding system. This might be a

result of several steps that were needed for the indirect bonding system. If the tooth surface of

a crowned area cannot be scanned accurately, transfer jigs produced from such virtual setup

data can be inaccurate. To reduce such scanning errors, a prosthodontic digital scanner at a

precision level of ±10 µm was used for experimental hard plaster model scanning. In

addition, the detail and accuracy of RP products reconstructed from digital data may not be

sufficient for certain applications when standard stereolithography techniques are used. The

RP technique can also introduce errors due to model shrinkage during building and post-

curing (Keating et al., 2008). Therefore, the adaptability of transfer jigs should be checked

before the bonding procedure. Other errors may occur during the fabrication of a customized

resin base or silicone transfer trays because these processes are executed manually. Control of

these manual errors is a key factor for successful virtual indirect bonding.

During the bonding procedure in the clinical setting, orthodontists can also make some

errors by using excess bonding materials or positioning trays incorrectly. The severity of errors

20

are various and difficult to predict. Such errors are the main disadvantage of the virtual

indirect bonding system. Despite errors in bracket positions, the new indirect bonding system

is clinically valuable. In the 018 slot orthodontic appliance, the 017*025 wire demonstrates

4.1° play. The mean torque difference was 4.84° ± 3.33°, and the tip difference was 1.39° ±

1.05°; these errors may be controlled with finishing wire bending. The mean depth difference

(0.33 mm ± 0.22 mm) was in acceptable ranges because only sealant resin materials were used

for bonding. Height errors may occur due to the malpositioning of transfer trays.

The largest torque error of the lingual and labial indirect bonding system using existing

manual procedure was 4.6° ± 2.5°(Shpack et al., 2007). This is comparable with results of this

paper.

There was no significant difference in tip and height according to tooth positions. The 2-

piece jig (incisors, canines, and second premolars) and 1-piece jig group (first and second

molars) showed significant differences in torque (P < 0.001) because different transfer jig

types were used. The 1-piece jigs were fabricated with an orthodontic wire that may rotate

during the bonding procedure. These results suggest the advantages and disadvantages of the

virtual indirect bonding system.

21

With the 3D virtual program, orthodontists can visualize many treatment options and decide

a proper treatment plan. Tooth size discrepancy, overjet/overbite, molar and canine key at the

final occlusion are easy to check in this program without the use of a complicated manual

setup procedure or occlusogram.

The main advantages of this new indirect bonding system are that it simplifies the technical

procedure and reduces time. This system enables a simple and rapid model setup that can be

easily modified. In addition, the virtual setup can serve as a communication tool with patients

or other clinicians. Also, virtual bracket bonding and fabrication of individual jigs can be

easily executed. CAD/CAM technologies facilitate this virtual setup and manufacturing

system. Many commercial brackets and wires in the software database can be used

individually.

The main problem with a virtual setup is technical sensitivity. The setup procedure is quite

simple but the result of the final setup depends on the operator. In addition, although the goal

is to set up the model three dimensionally, the virtual model on a computer screen can handle

only two dimensions, possibly leading to errors in alignment and occlusion. Therefore,

clinicians have to carefully check the alignment and final occlusion with a collision test. The

22

changes in tooth positions (torque, tip, and height) from initial to final should be checked for

the ideal setup. During virtual bracket positioning, the user must avoid penetrating the bracket

base through the tooth surface and avoid contact with the bracket margin and dentition of the

opposite arch; this can cause incorrect bracket positioning and bonding failure.

In addition, the quality of the initial impression is a key factor in this system. A silicone

rubber impression is recommended for this procedure. The accuracy of silicone rubber

impression has been provided at a precision level of 20 µm in ISO 4823. In addition, the

precision level of the laser scanner is approximately ±10 microns but representation of the

tooth contact area or undercut of the tooth is still limited. These problems with 3D dental

scanning need to be improved.

Further studies should focus on improving scanning methods and eliminating the manual

process of indirect bonding. Fabrication of a customized bracket base or a customized bracket

with CAD/CAM system requires new technologies.

23

. CONCLUSIONⅤ

Errors might occur during fabrication of the customized resin base or silicone transfer trays

because these processes are executed manually. In fact, some errors in all variables were found

in this study. Therefore, control of manual laboratory procedures is a key factor for successful

virtual indirect bonding along with the accuracy of digitations of plaster models. Clinically, in

the final stage of treatment, wire bending, re-setup of the models, or re-bonding of the

brackets may be required. Further studies are needed to improve the virtual indirect bonding

system.

24

References

Fillion, D. 2010. "Clinical advantages of the Orapix-straight wire lingual technique". Int

Orthod 8(2): 125-151.

Fillon, D. 2007. "Computer generated conception and fabrication of transfer trays for indirect

bonding of lingual attachments: The orapix system". Rev Orthop Dento Faciale 41:

61-75.

Geron, S. 1999. "The lingual bracket jig". J Clin Orthod 33(8): 457-463.

Hocevar, R. A., Vincent, H. F. 1988. "Indirect versus direct bonding: bond strength and failure

location". Am J Orthod Dentofacial Orthop 94(5): 367-371.

Hodge, T. M., Dhopatkar, A. A., Rock, W. P., Spary, D. J. 2001. "The Burton approach to

indirect bonding". J Orthod 28(4): 267-270.

Kalange, J. T. 2004. "Indirect bonding: a comprehensive review of the advantages". World J

Orthod 5(4): 301-307.

Keating, A. P., Knox, J., Bibb, R., Zhurov, A. I. 2008. "A comparison of plaster, digital and

reconstructed study model accuracy". J Orthod 35(3): 191-201; discussion 175.

Leifert, M. F., Leifert, M. M., Efstratiadis, S. S., Cangialosi, T. J. 2009. "Comparison of space

analysis evaluations with digital models and plaster dental casts". Am J Orthod

Dentofacial Orthop 136(1): 16 e11-14; discussion 16.

Milne, J. W., Andreasen, G. F., Jakobsen, J. R. 1989. "Bond strength comparison: a simplified

indirect technique versus direct placement of brackets". Am J Orthod Dentofacial

Orthop 96(1): 8-15.

Muller-Hartwich, R., Prager, T. M., Jost-Brinkmann, P. G. 2007. "SureSmile--CAD/CAM

system for orthodontic treatment planning, simulation and fabrication of customized

archwires". Int J Comput Dent 10(1): 53-62.

Okunami, T. R., Kusnoto, B., BeGole, E., Evans, C. A., Sadowsky, C., Fadavi, S. 2007.

"Assessing the American Board of Orthodontics objective grading system: Digital vs

plaster dental casts". Am J Orthod Dentofacial Orthop 131(1): 51-56.

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Redmond, W. J., Redmond, J., Redmond, W. R. 2004. "The OrthoCAD bracket placement

solution". Am J Orthod Dentofacial Orthop 125(5): 645-646.

Sachdeva, R., Fruge, J. F., Fruge, A. M., Ingraham, R., Petty, W. D., Bielik, K. L., Chadha, J.,

Nguyen, P., Hutta, J. L., White, L. 2005. "SureSmile: a report of clinical findings". J

Clin Orthod 39(5): 297-314; quiz 315.

Santoro, M., Galkin, S., Teredesai, M., Nicolay, O. F., Cangialosi, T. J. 2003. "Comparison of

measurements made on digital and plaster models". Am J Orthod Dentofacial Orthop

124(1): 101-105.

Shpack, N., Geron, S., Floris, I., Davidovitch, M., Brosh, T., Vardimon, A. D. 2007. "Bracket

placement in lingual vs labial systems and direct vs indirect bonding". Angle

Orthodontist 77(3): 509-517.

Sondhi, A. 1999. "Efficient and effective indirect bonding". Am J Orthod Dentofacial Orthop

115(4): 352-359.

KS P ISO 4823:2008, Dentistry－Elastomeric impression materials

26

국 문 요 약

3D 가상 프로그램을 이용한 설측 간접부착 술식의 정확성

<지도교수 : 차정열>

연세대학교 대학원 치의학과

최혜영

교정장치 부착의 정확성을 향상시키기 위해 다양한 방법으로 간접부착법이 발

전되어 왔으며 최근에는 컴퓨터 프로그램을 이용한 개별화된 치료가 개발되고 있

다. 컴퓨터 프로그램을 이용한 간접부착법이 간편하고 시간을 단축할 수 있는 장

점을 가지고 있으나 교합접촉이나 치아배열 등을 눈으로 직접 확인할 수 있는 기

존의 방법과 비교하여 정확성이 떨어질 수 있다는 지적이 있으며 jig 제작과 부착

에 있어서 다양한 오차가 발생할 수 있으므로 이러한 문제점을 파악하는 것이 중

요하다. 따라서 본 연구는 3D 가상 프로그램을 이용한 3차원 가상 모형 제작 및

이를 이용한 설측교정에서의 간접부착법의 정확성을 실험적으로 평가하고자 하였

으며 다음과 같은 결과를 얻었다.

1. 가상 프로그램상의 교정장치의 위치와 실제로 부착한 교정장치의 위치를 중

첩하여 torque, depth, tip, height의 오차를 측정한 결과 4가지 변수 모두에

서 유의차를 보였다 (P<0.001).

2. 각 계측치에서의 오차의 평균값은 torque는 4.84° ± 3.33°, depth는 0.33

mm ± 0.22 mm, tip은 1.39° ± 1.05°, height은 0.35 mm ± 0.27 mm 였다.

27

3. 상/하악과 좌/우측에서는 변수별 유의차가 관찰되지 않았다.

4. Torque에서 2-piece jig 그룹(전치, 견치, 제2소구치)과 1-piece jig 그룹(제

1,2 대구치) 사이에 통계학적 유의차가 관찰되었다(P<0.001).

제작된 jig를 이용하여 resin base를 형성하는 과정에서 기공작업으로 인한 오

차가 발생할 수 있으며 이는 가상프로그램을 이용한 간접부착술의 정확성을 감소

시키는 주된 요인이다. 본 연구에서 실제로 다양한 수준의 오차가 관찰되었으나

이러한 오차는 치료 마지막 단계에서 수정이 가능하다. 정확한 모델 스캔 및 장치

부착이 가상프로그램을 이용한 간접부착법의 성공을 위해 중요하다. 본 연구를 통

해 밝혀진 문제점의 개선과 함께 정확성을 향상시키기 위한 연구들이 뒷받침된다

면 가상프로그램을 이용한 교정진단 및 치료영역에서 더 많은 발전을 기대할 수

있을 것이다.

핵심 되는 말: 3D 가상 프로그램, 설측교정, 간접부착, 교정장치의 위치