Irritation of ocular tissue by irreversible hydrocolloids

-.30

-.25

J -

c

I

F

iT

-

-

-

Fig. 3. Percent change over 24 hours. E = Justi; L = Aristocrat; H = Hygon; K = Coe; A = Caulk; F = On-

tray; B = Langs; I = Fastray; C = Shurtray; 1 = Unitek; D = Duratray; G = Kayon. Materials E, L, and F expanded slightly as part of curing cycle.

SUMMARY Twelve commonly used acrylic resin tray materials were comparedfor linear curing shrinkage. Three of the 12 were found to expand slightly during the first few

hydrombids James R. Moergeli, John S. Ostrowsici,

Jr., D.D.S., M.A.,* Edward M. Fralcigh, D.D.S.,** D.M.D.,*** and George 8. Pelleu, Jr., Ph.D.****

Walter ReedArmy Medical Center, Washington,D.C.; and Naval Dental School,Naval Dental Clinic, Navnl Medical CommandNational Capital Region,Bethesda,Md.

‘I‘he

opmmns or assertions contained herem are the private ones of the authors and are not to be construed as offinal or as reflecting the

views Navy Conducted

of the

Department

aclurding

Care and Resources, 74-23. Supported by Development

Use of National

of the

to the prmrlplea Laboratory Research

Army

or the

set forth

Ammals. Council,

lunds provided under Navy Command Researt h Work

Department

of the

m the Guide

Institute DHEW,

of Puhl

hledrcal Irmt No

for

the

Laborator) No. (NIH)

Research Ml)O’)5-

dnd 00%

*(:olonel,

DC,

USA,

(:hlef,

Remwablc

Prosthodontlc

Srrv~w,

and

(Zhwf, ~laxdtolaclal Prosthetic S~rwce, IIq~t,d I)rntal Clmir Dental Actlwty. Walter Reed Army Mrdical Centrr **(:ommander Head, kf~xillofaci~i Pmsthettv Dwiamn, > DC 3 USN. Naval Hospital. San Diego, (:dllf Head, Prosthodontlcs Department and I,atw ***Captam > DC > USN. ratory, Branch Dental Chmc, Washington D C , formerly, Director. Maxlllofaual yrdm. N’avdl Drntal School.

,

Navy Yard, Washington, Rr~iduu~\ Tra~mnr: Pr
101-l

286

AUGUST

1985

VOLUME

54

NUMBER

2

IRREVERSIBLE

HYDROCOLLOIDS

AND

TISSUE

IRRITATION

Making impressions for the fabrication of ocular prostheses is an important step in recording anatomic contours of the residual orbital contents. An accurate impression is necessary for close adaptation of the mucosal surface of the ocular prosthesis to the posterior wall of the eye socket. Close adaptation to the mucosa will permit the use of the implant’s full potential for producing movement and eliminate voids where irritating mucus and debris may collect.‘,’ The patient’s comfort during the procedure is important but not always achieved. Different responses to irreversible hydrocolloid materials have been observed clinically. These range from slight irritation and dehydration of the orbital mucosa to transient cornea1 abrasion. Frequently, the dentist may observe signs such as reddening of the mucosa due to capillary dilation, edema, and prolific tearing when different commercial preparations of irreversible hydrocolloid are used. Patient responses include scratching, burning, stinging, and drying sensations that may last for a day or more after the procedure. These problems can be compounded if the impression must be removed during the same visit. Bartlett and Moore’ stated that no more than two impressions should be attempted at a single appointment because of the irritating effects of the irreversible hydrocolloid. No studies have been reported that specifically attribute the cause of irritation to a physically or chemically induced response. The flavoring oils and colorants in dental irreversible hydrocolloids have been implicated in the response,* but the real cause may be a combination of physical and chemical irritants. Most manufacturers of dental irreversible hydrocolloid state on the package that the product is for dental use only. Ocular supply firms recommend ophthalmic irreversible hydrocolloid for all ocular impressions. However, ophthalmic materials cost 75 to 100 times as much as dental impression material and are inconvenient to use because they are marketed in small packages. Their general use is, therefore, precluded for complete socket impressions. They can be used for cover shell prostheses and relining techniques, which require only small amounts of the material. Ophthalmic materials have the potential to cause adverse side effects similar to those commonly seen with dental irreversible hydrocolloid materials. This study compared the inflammatory response in the ocular mucosal membranes (conjunctivae) of rabbits to four irreversible hydrocolloid materials. MATERIAL

AND

METHODS

Forty adult New Zealand white rabbits weighing 3 to 4 kg each were selected for the study. The rabbit

*Peeler, THE

J.: Personal JOURNAI.

communication,

OF PROSTHETIC

1981 DENTISTRY

conjunctiva was chosen because it is the tissue of choice for toxicity evaluation of dental materials and products. The conjunctiva is extremely sensitive to chemical agents, it is a convenient size, and it provides an adequate histologic specimen.’ The rabbits were divided into four groups of 10 each. Each group was to be tested with one of four irreversible hydrocolloid materials. Proprietary information on the materials is shown in Table I. Jelset Special Formula and Kerr alginate Type II were selected as representative dental irreversible hydrocolloids. To standardize the procedure for obtaining the manufacturer’s recommended water/powder ratio, all the materials were weighed on an analytic balance and placed in individual sterile vials. Sterile distilled water at a temperature of 23” f 1” C was added at the time of spatulation according to recommended proportions (Table II). The tests were conducted in a clean surgical suite. Before the test, the ocular tissues of each rabbit were determined to be clinically healthy by a veterinary pathologist. Each animal was tranquilized by intramuscular injection of ketamine hydrochloride (Vetalar, 100 mg/ml, Parke-Davis Division, Warner-Lambert Co., Morris Plains, N.J.) 33.5 mg/kg and xylazine (Rompun, 20 mg/ml, Haver-Lockhart, Baynet Division, Cutter Laboratories, Shawnee, Kan.) 4.5 mg/kg. The animal was positioned and immobilized on the operating table. The irreversible hydrocolloid was hand spatulated for 1 minute as recommended by the manufacturer and injected from a 10 ml disposable syringe into a position over the left eye of each animal where it was allowed to fill both the superior and inferior cul de sac formed by the eyelids and the globe. The material was allowed to set and remain in contact with the tissue for 4 minutes before it was removed. A second mix of the same impression material was immediately reinjected into the same eye in the same way. This resulted in a total exposure time of 8 minutes for each conjunctiva. Thirty minutes after the second injection of impression material was removed, each rabbit was killed by intracardial injection of 0.3 mg/kg of pentabarbitol sodium (Somlethal, 6 mg/ml, D. M. Pharmaceutical, Rockville, Md.) solution. When vital signs ceased, the left ocular tissues were exenterated. The right untreated control ocular tissues were similarly exenterated. A suture was placed in the superior eyelid for histologic orientation of the specimens. The individual exenterated tissues were immediately placed in coded specimen bottles containing Karnovsky’9 fixative and delivered to the veterinary pathology laboratory for histologic processing and evaluation. The “in-block” dissections were hardened in 60% alcohol for 1 week. Sagittal sections were cut through each specimen with a microtome and stained with hematoxylin and eosin after routine processing. 287

MOERGELI

Table I. Proprietary

information

for irreversible --____--. ~.

Material

Modifiers

Ophthalmic Moldite Danker Laboratorlrb Sdrasota, Fla Ophthalmic Mold-Eye Robert B Scott Ocularlsts of Florida, Inc., Tampa, Fla. Jelset special formula Teledyne Dental Products Elk Grove Village, 111 Kerr algmate Type Kerr Manufacturing Romulus, Mich.

Magnrslum

tDA

carbonnteipartlcl~,

fluondt~

Dmtomaceous ~325 mesh

Potassium, fluoride

titanium, (I 96ri )

Dlatomaceous earth (35’; cnstobalitr, 54 h”r amorphous SIIIC~, 10.4q; Inert oxldes)/partlcle \xe--80?; were ~325 mesh

i-

No.

hlT(at

Blmetalllc

blur

1413035

i

-.-

proportions Powder

Ophthalmic Moldite Ophthalmic Mold-Eye Jelset special formula Kerr alginate Type 11

for Water*

(gm)

(ml)

4.50 4.75 4 50 3.25

15.0 135 13 5 10.0

was 13” + I “C.

These sectioning methods allowed investigators to examine an entire cross section of the spheres of interest while spatial relationships were preserved. The study was conducted in a blind manner so that only the surgical team knew the code that denoted the brand of irreversible hydrocolloid material and whether the specimen was of the treated or control ocular tissue. The prepared sections were evaluated independently by two pathologists for the presence of the following acute inflammatory microscopic changes: acute inflammatory response, vascular dilatation and engorgement, pavementing (peripheral orientation of white cells in the capillaries), and fluid exudation and polymorphonuclear leukocytes (PMN) outside vessels. These observations were graded from 0 to 4 as to degree of ipflammatory response according to the following criteria: 0 = Lack of margination of PMN; lack of PMN outside vessels 1 = Margination of PMN (mild); occasional widely scattered PMN outside vessels (<5/HPF [high-powered field]) 2 = Margination of PMN (moderate to marked); scattered PMN vessels (>5
tested* size

exth!partlclr (45 pm)

.\I

Co

Material

tempernturr

materials Filler/particle

t

I1

Table II. Water/powder irreversible hydrocolloids

*LVater

hydrocolloid

F1

3 = Margination of PMN (marked); numerous PMN outside vessels (>lO <20/HPF); frequent PMN migrating toward conjunctival surface 4 = Margination of PMN (marked), congestion of small vessels; numerous PMN outside vessels (>2OJ HPF); superficial vessel clogged by PMN and within connective tissue stroma For purposes of statistical evaluation, the tissue responses were grouped as to presence or absence of acute inflammatory response. A response graded <2 was considered a negative acute inflammatory response; a response graded ~2 was considered a positive acute inflammatory response, because it was found in preliminary results that the contralateral control eyes showed some degree of inflammatory response (possibly subacute) according to our grading criteria. The compiled inflammatory responses for each material were statisyitally compared with the control responses by chi square analysis, with ia = .Ol. RESULTS The number of conjunctivae that showed a positive acute inflammatory response is shown for each of the four impression materials (Table IIf). The results are shown for the untreated control and test eyes. Ophthal-~ mic Moldite had four (40%) of the control eyes and eight (80%) of the test eyes graded as having a positive acute inflammatory response. This difference was not signiiicant (p > .05). In similar comparisons of the acute inflammatory responses of Ophthalmic Mold-Eye (80%), Jelset special formula (SO%>, and Kerr alginate Type II (90%), differences were significant @ < .Ol). The dental impression materials produced a more severe acute inflammatory response as reflected in the higher average graded test responses (3 and 2.9), than the ophthalmic materials (2.5 and 2.3). The more severe AUGUST

1985

VOLUME

54

NUMBER

t

IRREVERSIBLE

HYDROCOLLOIDS

Table III. Number

TISSUE

of conjunctivae

Material Ophthalmic Moldite Ophthalmic Mold-Eye Jelset special formula Kerr alginate Type II *‘I‘m trcawd tSignilic,anily

AND

IRRITATION

showing

acute inflammatory

Control

Percent total

4 1 1 3

40 10 10 30

DISCUSSION Although Mold-Eye, Moldite, and Jelset each had an 80% test response and Kerr alginate Type II had a 90% positive test response, all test materials except Moldite elicited a significant acute inflammatory response in rabbit eyes. It is possible that Moldite did not produce a significant acute inflammatory response because of the high incidence of acute inflammation seen in the control eyes. A subclinical acute inflammatory reaction might have gone undetected in the 10 animals clinically screened by the veterinarian before testing. The average graded inflammatory responses were lower for the Moldite and Mold-Eye materials than for the Jelset and Kerr materials, which suggests that the ophthalmic materials are less inflammatory than the dental materials. This implication is supported by findings of increased eosinophil counts in regions of greatest inflammatory responses. The increased eosinophilic infiltration may mean that there is an overlying allergic reaction, because eosinophils are believed to respond to stimuli derived from mast cells, lymphocytes, and serum factors, including complement factors C3a and C5a, and are consistently found in tissues in which there is a known allergic condition5 There are potential antigens in the ingredients, possibly the alginic acid itself, which is a polymer of high molecular weight, or perhaps haptens contained within the chemical makeup of the irreversible hydrocolloids. Although the purpose of this study was not to determine the agent or agents that cause the inflammatory response, it appears that the insult may be both physical and chemical. The mere injection of a foreign granular substance against the conjunctiva with the concurrent twitching and blinking of the eye and lids may cause superficial abrasion of the tissues. If this physical insult is compounded with an overlying chemical irritant, the potential for an acute inflammatory response is realized. The potential for physical insult from abrasion JOURNAL

Test

Percent total

8 8 8 9

80 W sot w

of

of

Average graded test responses 2.5 2.3 3.0 2.9

wnjuncti\ae pw material. Contrala~ral eye served as control rl~iTcwnt from control by chi square analysis (/I < .Ol)

acute inflammatory response was accompanied in each instance by an increase in the number of eosinophils.

THE

responses*

OF PROSTHETIC

DENTISTRY

appears to be less for the ophthalmic materials because they are composed of a finer and lower density powder and produce a mix that was subjectively judged by us to be creamier and less granular. Although these materials appear to be clinically superior, the particle size cited by the manufacturer of Jelset is comparable to that of at least one of the ophthalmic materials tested (325 mesh size). Quality control or method of manufacture may play a role in the final product. None of the impression materials tested contain coloring or flavoring agents, but they do contain various chemical modifiers that have the potential to cause a chemical insult. These modifiers are used primarily to counteract the inhibiting effect of the hydrocolloid on the setting of gypsum. The modifiers used in relatively high concentrations, such as the bimetallic fluorides in MoldEye and Jelset Special Formula or the silica and borates used in other irreversible hydrocolloids, as modifiers may have an irritating effect on the conjunctival tissue. The hydrogen ion concentration, the time from start of the mix to application, and unknown factors in the setting reaction of irreversible hydrocolloids may play a role in the inflammatory response. Filler and particle size varied among the materials. Mold-Eye and Jelset both use diatomaceous earth with a mesh particle size of 325 (45 pm) or less. Ophthalmic Moldite contains magnesium carbonate; the manufacturer does not provide information on the particle size. Most companies were reluctant to disclose what they considered to be trade secrets. Further studies of the physical and chemical irritant properties of ocular impression materials are needed. Because of the extreme price difference between ophthalmic and dental irreversible hydrocolloid, it may be advantageous to continue to use the less expensive nonflavored dental materials for most patients and use the ophthalmic materials only for patients who demonstrate adverse clinical reactions to the dental materials. It would also be advantageous to clinicians if manufacturers of irreversible hydrocolloids were required to list the ingredients on the package by percent of weight 289

so that a reasonable decision could be made as to the suitable use of a specific material. Because of the extremely subjective nature of pain, it is difficult to evaluate clinically, the actual irritating effect of the material. The severe adverse reactions seen clinically appear to be idiosyncratic, with a particular brand of irreversible hydrocolloid causing a reaction only in specific individuals. The inflammatory response is short lived, usually with total resolution in 24 to 72 hours.

SUMMARY Two ophthalmic and two dental irreversible hydrocolloid materials were tested on rabbit conjunctivae to determine histologically their potential to irritate these tissues. Each of the four impression materials elicited nearly the same amount of inflammatory response. The differences between the response of the controls and the response to Ophthalmic Mold-Eye, Jelset Special Formula, and Kerr Alignate Type II were significant. These results indicate that certain dental irreversible hydrocolloids may be used for ocular prostheses but that they should be used with caution because of the inflammation caused by irreversible hydrocolloids.

David J. Mishkin, Brad W. Neville, Medical

University

D.M.D.,* D.D.S.*** of

South

Mike

Carolina,

A. Davis, D.D.S., M.H.S.,**

College of Dental Medicine,

A

and

Charleston, SC.

lveolar ridge irregularities such as undercuts and atrophy posea major problem in the fabrication of fixed and removable prostheses.Attempts to manage these problems have included alveolectomy/alveoplasty and augmentation of the ridge through autogenous and ailogenic osseousgrafts; autogenousgingival grafts; and alloplastic implants such as stainless steel, silicone, silicone backed with dacron mesh or polyurethane, proplast, scleral allografts, and hydroxylapatite.‘-* The major disadvantageof these proceduresis the morbidity associatedwith surgical procedures.

Surgical augmentation of ridge undercuts could be averted if it were possible to inject a biocompatible material into the space to obliterate the undercut. Solubilized bovine-derived collagen xenogeneic grafting material has been shown to be an effective and biocompatible matrix for subsequentconnective tissue deposition when injected subcutaneouslyinto Sprague-Dawley rats.’ The purpose of this study was to evaluate the histologic results obtained from the injection of this material into the oral mucosaof Sprague-Dawley rats and to determine whether it could serve as an adequate matrix for connective tissuedeposition,and thus be used for alveolar ridge augmentation in humans.

*Assoriatr **Private ***A&tan1 Path&y.

MATERIAL

290

Professor, Department of Periodontics. practirr, Lyndhurst, Ohio. Prdrssor. I)rpartrncnt of Or;tl

I)iagnosis

xntl

Oral

AND METHODS

Two types of solubilized bovine-derived collagen, Zyderm (Collagen Corp., Palo Alto, Calif.) and glutaAUGUST

1985

VOLUME

54

NUMRER

2