A comparison of Wear Resistance of five brands of

Original article

A comparison of Wear Resistance of five brands of commercially available Acrylic Denture Teeth- An in Vitro Study

S. P. Joshi*, M. D. Souza**

AbstractWear of intra-oral restorative material is an area of concern in clinical dentistry. Five brands of commercially available acrylic teeth were taken in this study. The pin and disc apparatus was used for testing the wear resistance. Each specimen was subjected to two 500 cycles of wear. Height loss and weight loss were measured and used as parameters to evaluate the wear resistance of the teeth. The wear resistance was found to be different for different brands of acrylic teeth. The density of the teeth had a direct bearing on the abrasion resistance of teeth.

Key WordsWear resistance, acrylic, denture teeth.

IntroductionWear or deterioration of intra-oral restorative material is an area of concern in clinical dentistry. Wear results wherever relative motion and force are present. Tooth wear continues to be a major problem for patients with artificial teeth. It is of concern because it will cause loss of vertical dimension, loss of masticatory efficiency, faulty tooth relationship, and increased horizontal stresses and their associated sequelae1. Acrylic denture teeth has been taken as the study material in this study .

Materials and MethodsThe different brands of denture teeth used in this study are Acry Rock (Italy), Premadent (India), Peridon (India), Oradent (India) and New Ace(Japan).

The weight of each brand of denture teeth was taken out by weighing all the posterior teeth of the lower arch of each set in an electronic balance up to the accuracy of 10 -4 gm. The volume was measured by dipping them in a measuring glass which could read up to 0.2 mm accurately. Density of each brand was calculated after dividing mass by volume.

An acrylic rod was next prepared to facilitate attachment of the specimen to the specimen holder of the wear apparatus. These rods were made of self cure acrylic for each tooth specimen, to facilitate attachment of the specimen to the specimen holder of the wear apparatus. The rods were made from a metal cylindrical die 6 mm in diameter and 18 mm in length.

The teeth specimens were made to an exact size of 6x6 mm. The dimensions were measured with a screw gauge of 0.1 mm accuracy.

A total of fifty specimens, ten of each brand were prepared, using the first upper and lower molar teeth. The specimen tooth along with attached rods were weighed. The pin and disc apparatus was used in this study.2 The specimens were then ground with water lubricated 600 grit silicon carbide paper which was attached to the surface of the disc on the apparatus3. The specimens were subjected to 500 cycles then removed from the testing device, cleansed of all debris and weighed in the electronic balance4. Wear was measured by loss of weight in 500 cycles. Measurement of the wear resistance in

_______________________________________________________*Consultant dental surgeon and prosthodontist, Bir Hospital, **Professor of Prosthodontics, CODS, Manipal, India.

terms of loss of volume of teeth was calculated from the previous reading taken for the loss in weight and the density of the teeth. The formulae used were

Loss of volume of the teeth =

teethofDensityteethofweightinLoss

× 1000

Loss of height of teeth =

AreateethofvolumeofLoss

where area for all specimen is 36 mm2

Data was fed into the computer in dBASE and analyzed using statistical package SPSS.

All variables in different groups were compared using One way analysis of variance followed by Duncan Multiple range test. Results were expressed in terms of mean and standard deviation. A p value < 0.05 was considered significant.

ResultsA two body wear test was conducted to compare the wear resistance of five brands of commercially available denture teeth.

A total of 50 specimens were prepared with each group containing ten specimens.

Table 1. Brand names and densities in gm/cc of various acrylic teeth

Group Brand Name Density gms/cc12345

New AceAcry RockPremadentPeridonOro dent

1.1851.1881.2041.1861.187

The brand names and density of each group of teeth are tabulated in Table 1.

Table 2. Mean weight loss with standard deviation in the 1st 500 cycles

Group Mean Standard Deviation1. New Ace2. Acry Rock3. Premadent4. Peridon5. Oro dent

0.01920.01420.01390.01630.0182

0.00470.00350.00440.00350.0040

The mean and standard deviation of weight loss of each group of teeth subjected to the first 500 cycles is given in Table 2.

Table 3. Mean weight loss with standard deviation in the 2nd 500 cycles


0.01720.01700.00980.01020.0117

0.00330.00370.00130.00360.0032

This table shows the mean and standard deviation of weight loss of each group of teeth subjected to the second 500 cycles. New Ace which showed mean of 0.172 and standard deviation of 0.00333 and Acry Rock which showed the mean of 0.0170 and standard deviation of 0.037 had higher weight loss than the other brands.

Table 4. Mean weight loss with standard deviation in the overall 1000 cycles


0.03640.03120.02380.02650.0299

0.00620.00610.00430.00570.0065

The mean and standard deviation of weight loss in the overall 1000 cycles is shown in Table IV.

Table 5. Mean height loss with standard deviation in the 1st 500 cycles


0.45010.33160.32160.38200.4247

0.11110.08260.10110.08220.0947

Height loss is calculated by by dividing volume loss by area.

Table V shows the mean and standard deviation of height loss of each group in the first 500 cycles. Premadent showed the least height loss with mean of 0.3216 and standard deviation of 0.1011. New Ace showed the greatest height loss with a mean of 0.4501 and standard deviation of 0.111.

Table 6. Mean height loss with standard deviation in the 2nd 500 cycles


0.40200.39700.22660.23940.2747

0.07720.08730.02980.08500.0739

This table shows the mean and standard deviation of weight loss of each group of teeth subjected to the second 500 cycles. New Ace which showed mean of 0.172 and standard deviation of 0.00333 and Acry Rock which showed the mean of 0.0170 and standard deviation of 0.037 had higher weight loss than the other brands.

Of the means and standard deviations of height losses in the second 500 cycles, Premadent showed the least height loss with a mean of 0.2266 and standard deviation of 0.0298 and New Ace showed the greatest height loss with a mean of 0.4020 and standard deviation of 0.0772.

Table 7. Mean height loss with standard deviation in the overall 1000 cycles


0.85210.72860.57820.62140.6995

0.14470.14170.09910.13360.1520

Of the means and standard deviations of the height losses in the overall 1000 cycles, Premadent showed the least height loss with a mean of 0.5782 and standard deviation of 0.09991 and New Ace showed the greatest height loss with a mean of 0.8521 and standard deviation of 0.1447.

Table 8. Density, means loss in height and weight as a measure of wear resistance

Brandsof teeth

Weight Loss (gms)

Height Loss (mm)

Densitygms/cc

12345

0.03640.03120.02380.02650.0299

0.85210.72860.54820.62140.6995

1.1851.1881.2041.1861.187

Table VIII shows the various brands of teeth and mean values of their resistances and densities. The wear resistances was found in the order of Premadent, Peridon, Oral dent, Acryl Rock and New Ace.

DiscussionAcrylic teeth are widely used in complete and removable partial dentures and over the years the functional and esthetic characteristics of denture teeth have been improved , they do however undergo wear which can unfavorably affect the occlusal vertical dimensions and tooth relationship causing stresses on the oral mucosa and adversely influencing esthetics. This study was conducted to compare the wear resistance of five brands of commercially available acrylic teeth. These brands were chosen for the study as

they were easily available and also they were commonly used.

Fig. 1: Five Different Brands of Teeth used in this Study

A modification of the pin and disc apparatus was used in this study 3.

Fig. 2: Pin and Disc Apparatus

Fig. 3: Prepared Tooth Specimen fixed on Acrylic Rod

The densities of the various brands of the acrylic teeth used in this study are shown in Table I.

The mean weight loss with standard deviation in the first 500 cycles and the second 500 cycles are shown in Tables II and III. The mean weight loss

with standard deviation in the overall 1000 cycles is shown in Table IV.

The mean height loss with standard deviation in the first 500 cycles and in the second second 500 cylcles are shown in Tables V and VI respectively. These values have been further elaborated as the mean height loss with standard deviation in the overall 1000 cycles in table VII.

The result of this study showed the mean wear for New Ace 0.8521,Acry Rock 0.7285, Premadent 0.5482, Peridon 0.6214 and Oradent 0.6995.

The density of the teeth had a direct bearing on the abrasion resistance of teeth5. Premadent with the highest density of 1.204 had a least wear of 0.5482 and conversely New Ace the least density of 1.185 had the most wear of 0.8521.

Further studies can be carried out, to clinically evaluate the wear of the same brands of teeth, in complete denture wearers.

References1. Ogle RE,Devils DE. Clinical wear study of

three commercially, available artificial tooth materials .Thirty six month results .J Prosthet. Dent.1998;79:145-151.

2. Khan Z,Morris JC,von Fraunhofer JA. Wear of non-anantomic (monoplane) acrylic resin denture teeth. J Proshtet Dent 1984;52: 172-174.

3. Whitman DJ,McKinney JE,Hinman RW, Mesby RA, Pelleu GB. In vitro wear rates of three types of commercial denture tooth materials. J Prosthet Dent 1987;57:243-246.

4. Smalley WM,Nicholls Jl. In vitro two body wear of polymeric veneering materials.J Prosthet.Dent. 1985;56:176-181.

5. Khan Z,Morris JC,von Fraunhofer JA. Wear of non-anantomic (monoplane) acrylic resin denture teeth. J Proshtet Dent 1984;52:

6. Verma AK,Tandan BK,Aggrawal NK. A comparative study of wear resistance of acrylic teeth produced in India. J Indian Dent. Assoc. 1985;57:65-68

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A comparison of Wear Resistance of five brands of