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BIOMAT., MED. DEV., ART. ORG., 7 ( 2 ) ,
207-212
(1979)
IMPORTANCE OF DESIGN, CONTROL, & QUANTITATIVE DATA IN DENTAL CLINICAL RESEARCH
J.D. Eick, Ph.D. and R.D. Lamb, M.S. Department of Reconstructive Dentistry School of Dentistry Oral Roberts University Tulsa, Oklahoma 7 4 1 7 1 ABSTRACT The ultimate test of a restorative dental biomaterial is its performance in vivo. Often laboratory test data does not correlate directly with clinical performance, s o clinical research with human patients is essential. Clinical research that obtains maximum information from a minimum number of patients m u s t be well designed and controlled. Pilot studies are necessary to establish experimental conditions and to determine the sample size. Previous clinical studies with various restorative materials have shown that careful screening and comprehensive oral examinations of patients are necessary to insure maximum recall for evaluation. Controlled placement procedures and randomized alloy placement are extremely important. Restorations are evaluated both by the response of patients to the restorations and by trained and calibrated dental examiners using established ranking criteria. Quantitative data measured in vivo such as that obtained from stereophotogrammetry reduced the need for large patient populations. The interfacing of a computer to record patient, placement, and evaluation data assisted greatly in project management. Introduction The intent of this paper is to summarize the important steps needed for dental clinical research.
These include:
(1) The
clinical research team, (2) The pilot study, ( 3 ) Patient selection,
207 Copyright 0 1979 hy Marcel Dekker. Inc All Rights Reserved. Neither this work nor any part may he reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming. and recording, or by any information storage and retrieval system, without permission in writing from the publisher.
208
EICK AND LAMB
(4) Placement p r o c e d u r e s ,
(5) E v a l u a t i o n
procedures,
(6) Data
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a n a l y si s- - c o m p u t er u s e , and ( 7 ) Qu es t i o n s remaining.
R e s u l t s and D i s c u s s i o n The c l i n i c a l r e s e a r c h team:
There i s u s u a l l y a minimum of
f i v e members n e c e s s a r y t o conduct c l i n i c a l r e s e a r c h i n d e n t i s t r y . These p e o p l e i n c l u d e t h e d e n t i s t , t h e d e n t a l a s s i s t a n t , a r e c o r d e r , and two d e n t a l examiners o r e v a l u a t o r s .
An i n d i v i d u a l r e c o r d s
placement d a t a t o en s u r e t h a t t h e d e n t i s t f o l l o w s t h e p r o t o c o l and t h a t t e s t m a t e r i a l s a r e p l a c e d randomly.
The r e c o r d e r s i t s w i t h t h e b
d e n t a l team a s t h e c a v i t y i s p r e p a r e d and a s t h e r e s t o r a t i v e material i s placed.
I f q u a l i t a t i v e e v a l u a t i o n d a t a i s o b t a i n e d two
c a l i b r a t e d d e n t a l e v a l u a t o r s a r e needed.
These i n d i v i d u a l s should
be s t a n d a r d i z e d a g a i n s t s p e c i f i c c r i t e r i a , i . e . , t h e U.S.P.H.S. criteria.’
N e i t h e r one o f t h e e v a l u a t o r s should be t h e d e n t i s t t h a t
performed t h e i n i t i a l placement o f t h e r e s t o r a t i o n , t h u s minimizing bias.
The p r o j e c t d i r e c t o r must f u n c t i o n a s a manager
and
f a c i l i t a t o r , making s u r e t h a t t h e r e s e a r c h team f u n c t i o n s w e l l together. P i l o t s t u dy :
I t i s good p r a c t i c e t o perform a p i l o t s t u d y i n
any kind o f r e s e a r c h , whether i t i s l a b o r a t o r y o r c l i n i c a l . especially true i n c l i n i c a l dental research.
This is
Q ue stions c onc e rning
t h e number of p a t i e n t s , how a r e p a t i e n t s s e l e c t e d , armamentarium and p r o c e d u r a l l i s t s f o r p l acemen t , e v a l u a t i o n c r i t e r i a , s t a t i s t i c a l a n a l y s i s methods need t o be answered.
and
209
DENTAL CLINICAL RESEARCH
Patient selection:
A fundamental criteria for conducting
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clinical research is wise patient selection. What is the number of patients needed for the study? This question was a major issue of a conference recently sponsored by the ADA and NIH.’ Are the patients suitable for the study? Do they need dental care that appropriately fits into the study and are they willing to be included in the study? The protocol for the research project must be reviewed and approved by the Human Subjects Committee. Each patient must be fully informed of the research project both in writing and verbally and they must sign the informed patient consent form. important aspect is the recallability of patients.
Another
Issues such as
previous longevity in the area, age, and responsibility need to be evaluated. Placement procedures: Five steps need to be considered: (1) the dental procedures used by the dentist, (2) the role of the dental assistant, ( 3 )
the role of the recorder, ( 4 ) the
randomization procedures, and placement.
( 5 ) patient
obligations after
In the initial pilot study the dental procedures and
armamentarium list should be established by the dentist. Likewise the role of the dental assistant in the project needs to be determined. The role of the dental recorder i n maintaining patient records and recording during placement should all be defined. Randomizing the placement of materials is important and patients should act as their own controls. I n addition, what obligations are needed to the patient after placement of the restorations? Even
EICK AND LAMB
210
though the project dentist may not be responsible for the total
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dental care of the patient, there are certain dental obligations that remain. For example, sometimes a tooth cusp breaks and a particular restoration needs to be replaced. These type of problems require dental care for the duration of the study. Evaluation procedures:
In dental clinical research, each
patient usually acts as their own control. Therefore differences at base line vs. one year, two years, or three years of a control alloy v s . a test alloy are measured. Much of the current research is done 1
using evaluation systems that have been developed by Dr. Ryge or by Dr. Mahler
3
.
These
involve ranking systems which
generate
qualitative data. The statistics that are applied to these types of systems are non-parametric, and specific designs and statistic test methodology are applied. Depending upon the system used, clinical evaluators, calibrated against a standard using specific criteria, are employed.
I n our laboratories we are attempting to provide
clinical evaluation systems that provide quantitative data.
For
example, we have developed a stereophotogrammetry system that produces quantitative data. 4-6
The stereophotogrammetry system
involves taking stereophotographs of the restoration in question, and then plotting the restoration in three-dimensions to measure the marginal breakdown and contour changes. The system is accurate to 5 pn and clinically reproducible to 25 pm.
By obtaining
quantitative data such as this, the statistical analysis used on the data is parametric and the number of patients needed to declare a difference between the control and the test alloys is less. Table 1
211
DENTAL CLINICAL RESEARCH Table I
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Comparison Between Ratings Sample No.
USPHS
Mahler ' s
Ranking
Ranking
Photogrammetry width
depth
pm
pm
vol./length
3
/m
x~o-~ 21u1
Alpha Alpha Bravo
21U3 5u3 t w
-
2
32Ot?75XW 5025% 190+60%
3 4
1002140% 52155% 402165%
2390285% 152120% 5402195%
mean reported to nearest 5pm coefficient of variation
lists a comparison of data obtained from three restorations using two of the qualitative ranking
and data obtained by the
stereophotogrammetry system.4-6 As can be seen, there was a significant difference between the systems. Data analysis/computer use:
The inclusion of a computer
enhances the ability to conduct the research.
For example, the
computer can store patient demographic data, patient medical histories, and be use$ to recall patients for evaluations.
It can
also be utilized to store evaluation data and perform the statistical analysis on the data. Summary
-
Questions Remaining
The above steps (clinical research team, pilot study, patient selection, placement procedures, evaluation procedures, and data analysis-computer use) are necessary to perform good clinical research.
There are several questions remaining, which include:
EICK AND LAMB
212 (1)
What is the number of patients needed for clinical studies? ( 2 )
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What type of data is obtained? Quantitative methods for clinical evaluation need to be developed.
( 3 ) What type of statistical
analysis should be applied to the data that is obtained? ( 4 ) What is the clinical significance of the data obtained and how does the clinical significance correlate with statistical significance? These are a few of the questions which remain. References 1.
Cvar, J . F. and Ryge, G., Criteria for the clinical evaluation of dental restorative materials. GPO 790-244, 1973.
2.
CDMD, FDA, and NIDR Conference, Clinical evaluation of dental materials, ADA Headquarters Building, Chicago, Illinois, June, 1978.
3.
Mahler, D. B . , Terkla, L. G., and Van Eysden, J., Marginal fracture of amalgam restorations, J . Dent. Rer. 2 : 8 2 3 , 1973.
4.
McGivern, R. F., Eick, J . D., Sorensen, S . E., Development and evaluation of a method of photogrammetry for measuring topographical changes of restorations in the mouth. Proceedings of the Symposium on Close-Range Photogrammetry, University of Illinois, p. 3 0 3 , January, 1971.
5.
Eick, J. D., Ortman, L. F., Allen, T. B . , and McGivern, R. F., General clinical application of a stereo-camera system, IADR Abstract No. 6 4 2 , 1973.
6.
Eick, J. D., Jendresen, M. D., and Ryge, G., Comparison of three clinical evaluation systems used with amalgam restorations. IADR Abstract No. 5 1 4 , 1976.