Sri Ramakrishna Dental College and hospital

Department of prosthodontics

Coimbatore-641006

Thesis Protocol

A comparative study to measure the temperature change occurring in the pulp chamber during polymerization

reaction of three commercially available direct provisional materials- In vitro

August 2012 Dr. Magesh.P

Sri Ramakrishna Dental College and hospital

Coimbatore

MDS(Prosthodontics)

A comparative study to measure the temperature change occurring in the

pulp chamber during polymerization reaction of three commercially

available direct provisional materials- In vitro

Guide: Dr. V.R. Thirumoorthy, MDS

Head Of the department and Professor

Department of Prosthodontics

Sri Ramakrishna Dental College and hospital

Candidate: Dr. Magesh.P

Post Graduate student

Department of Prosthodontics

Sri Ramakrishna Dental College and hospital

Contents:

Introduction

Review of literature

Objectives of the study

Materials and methods

Exclusion criteria

Methodology

Armamentarium

Materials used

Method of collection of data

Procedure

-Fabrication of Study Model

-Fabrication of Matrices

- Fabrication of provisional crowns

Statistical analysis

List of references

INTRODUCTION

A provisional restoration in fixed prosthodontics is one that is designed to enhance

aesthetics, stabilization and/or function for a limited period of time after which it is to be

replaced by a definitive fixed prosthesis. It must fulfil biological, aesthetic and mechanical

requirements. Protection of the pulp is one of the principal biologic requirements. The

material and technique of fabricating the provisional restoration itself must not endanger

pulpal health.

There are two principal ways of fabricating the restorations, indirect and direct

method. Though the indirect method is the healthier option for the pulp, it is time consuming

and cumbersome. It also involves an additional appointment for the patient. Therefore,

clinicians largely prefer the direct method of fabrication of fixed provisional restoration.

The direct technique presents two major problems. The first problem consists of the

presence of free monomer, which can be harmful to the pulp. Secondly, most of the materials

induce a temperature rise during polymerisation. Thermal damage includes various

histopathological changes of the pulp such as cellular degeneration, destruction of

odontoblasts, coagulation of protoplasm, or localised or generalised tissue necrosis.

Clinically, the patient could have persistent sensitivity, transient pain or even irreversible

pulpitis.

Literature states that there is a rise in intra-pulpal temperature, but does not document

the quantum of rise or the most reliable ways of preventing or minimizing the same. Some

authors have recommended cooling the index prior to provisional fabrication such that the

temperature rise in the material is offset by the cooled index.

Thus certain precautions should be taken while selecting the material for provisional

restoration to protect healthy pulpal tissue. Methods to protect the pulp with insulating

mediums have been used.

This study intends to compare the temperature increase with three types of commonly

used provisional restorative materials and three different types of indexes namely,

polyvinylsiloxane putty, vacuum formed template and alginate matrix.

REVIEW OF THE LITERATURE:

1. The pulp can be subjected to lesions resulting from caries or trauma. The latter can be

iatrogenic, resulting from removal of previous restorations, tooth preparation procedures,

desiccation, or fabrication of provisional restorations.

2. Michalakis et al measured the intrapulpal temperature during fabrication of provisional

restoration using a polymethyl methacrylate (PMMA), a polyethyl methacrylate (PEMA), a

polyvinylethyl methacrylate (PVEMA), a Bis-acrylic composite, and a visible-light

polymerizing (VLP) urethane dimethacrylate and found that polymethyl methacrylate

(PMMA) resin produced the highest exothermic reaction (40.50 ºC) of all materials tested.

3. An in vivo study conducted by Zach and Cohen in the year 1965 showed that temperature

rise of 5.6º C can lead to a 15 % loss of vitality in the pulp, 11º C temperature rise about 60

% and 16.6º C temperature rise causes 100 % necrosis of the pulp.

4. Aysegul G. Gurbulak et al investigated the effects of different desensitizers and an

adhesive material application on pulpal temperature rise during direct provisional restoration

polymerization and found that temperature rise varied according to the provisional restoration

material used ( the composite resin-based provisional material induced higher thermal

changes than methacrylate based provisional material ), the agent thickness (application of

two layers are more effective than single layer of dentin desensitizers or dentin adhesive ),

and the agent ( less temperature increase with adhesive than the desensitizer).

5. The reaction of the polymer-based provisional material is an addition polymerization. As

the polymerization proceeds, carbon–carbon double bonds (p-bonds) are converted to new

carbon–carbon single bonds (s-bonds). The carbon–carbon s-bond has energy of about 350

kJ/mol, and the carbon–carbon p-bond has 270 kJ/mol. The difference in energy between the

two bonds, 80 kJ/mol, emits as heat.

6. Sung Hun Kim et al measured the polymerisation temperature of four provisional

materials Three Dimethacrylate based materials (Fast set Temphase, Protemp 3 Garant and

Luxatemp) and one monomethacrylate based material (Trim). Fast set Temphase showed the

highest peak temperature (12.7º C ) followed by Protemp 3 Garant (7.6º C), Luxatemp (6.9º

C) and Trim (5.1º C).

7. A study is conducted by Giuseppe Chiodera et al to measure the temperature change in

the pulp cavity of an extracted tooth during the polymerization of one acrylic temporary resin

Trim (Bosworth Company, 7227 North Hamlin Avenue, Skokie, IL, USA) and two bisacryl

type resins Cooltemp (Coltene Whaledent AG, Alstatten, Switzerland) and Integrity

(Dentsply GmbH, Konstanz, Germany) used for fabricating provisional crowns. Temperature

rise of 3.4 ºC for Cooltemp, 3.7 ºC for Trim and 5.5 ºC for Integrity is noted.

OBJECTIVES OF THE STUDY:

The present study is designed with the following objectives:

To determine and compare the temperature increase in the pulp chamber of

permanent molar tooth placed in contact with different resins used for the direct

fabrication of provisional restorations.

To examine the ability of different indexes used with the same provisional

restorative material to dissipate the heat produced during the polymerization

reaction

MATERIALS AND METHOD:

Recently extracted molar tooth stored in 1% Choramine solution for two weeks

EXCLUSION CRITERIA:

- Decayed/ restored teeth

- Severely attrited teeth

- Endodontically treated teeth

METHODOLOGY:

ARMAMENTERIUM:

1. K - Type thermocouple probe with an electronic digital indicator (Type K

Thermometer Thermocouple LCD Digital TES-1310)

2. Diamond points.

3. Micromotor with carborundum disc.

4. Airotor hand piece

5. Electric timer.

6. Mortar and pestle

7. Amalgam carrier and amalgam condenser.

MATERIALS USED:

1. Provisional restorative materials

o UniFast III (GC, Japan)

o Protemp 4 (3M, Germany)

o DPI Tooth moulding Powder( DPI, India)

2. Petroleum jelly

3. Dental amalgam

4. Polyvinyl siloxane putty impression material (Aquasil, Dentsply, Germany).

5. Alginate impression material( Neocolloid, Italy)

6. Vacuum formed template

7. 5.25% sodium hypoclorite solution

8. Autopolymerising acrylic resin (D.P.I).

9. 1% Chloramine solution

10. Water

METHOD OF COLLECTION OF DATA:

Group A: Polyvinylsiloxane putty impression index group.

Group B: Vacuum formed template (1mm thick) group.

Group C: Irreversible hydrocolloid (alginate) index group

Each group is further divided into three subgroups asfollows:

Subgroup 1: Provisional restorations made with Uni Fast III

Subgroup 2: Provisional restorations made with Protemp 4

Subgroup 3: Provisional restorations made DPI tooth moulding powder

Total sample size: 90

Procedure:

Fabrication of Study Model

A model is constructed representing a partially dentulous mandibular arch with missing right

first molar. A complete arch typodont model is duplicated in agar. Extracted natural tooth of

average size and form is selected for use in this model. The mould is then completely filled

with molten modeling wax. After solidifying, wax model is retrieved from the mould, the

natural tooth is aligned slightly and the model is smoothened. An alginate impression is

made of the wax model and poured in type IV dental stone to be later used in the

fabrication of matrices.

The model is invested and after dewaxing the natural tooth is retrieved. The root of molar is

sectioned approximately 3 mm below the CEJ. The pulp chamber is cleaned of organic

debris. A thermocouple probe is positioned inside the pulp chamber (attached to digital

thermometer on the other end) and amalgam is condensed around the probe, filling the

pulp chamber. The tip of the probe is the only part sensory to the temperature changes.

Silver amalgam is condensed around the probe tip acts as heat conduction medium from

dentin to thermocouple probe.

The tooth is placed in respective position in the plaster mould obtained after dewaxing.

After applying cold mould seal the mould is then processed with autopolymerising acrylic

resin. The acrylic resin model is then recovered, trimmed and polished. The natural tooth is

then prepared for complete coverage porcelain fused to metal retainers. The model is now

ready for fabrication of provisional crown.

Fabrication of Matrices

The matrices are fabricated as follows:

Irreversible hydrocolloid (alginate) matrix:

The stone cast is immersed in a plaster bowl of water for 5 min. Wetting the cast in

this manner will prevent the alginate from adhering to it. Alginate is mixed according to

manufacturer’s instructions and loaded in posterior sectional tray. The sectional tray with

alginate is positioned over the stone cast, to make an impression. A new impression is made

for each trial.

Polyvinyl siloxane putty matrix:

Before making the matrix, the impression tray is painted with tray adhesive and

allowed to air dry for 5 min. Equal and constant proportion of base and catalyst of polyvinyl

siloxane putty impression material are mixed by kneading in the hands and placed in

sectional tray to make an impression of the stone cast. Excess impression material from the

borders is trimmed to facilitate accurate re-placement on the study model. Total three

impressions are made to fabricate provisional restorations with the three resins in the

study.

Vacuum formed template matrix:

Thermoplastic sheet is adapted over the stone cast using thermal vacuum forming

machine. The vacuum template is trimmed 5 mm below the CEJ of the teeth and is also cut

such that it extended one tooth on either side of the prepared teeth to serve as stops. A

total of three such templates are fabricated.

Fabrication of provisional crowns:

Petroleum jelly is applied to the tooth and surrounding acrylic resin model. For all

techniques the provisional resin materials are measured and mixed according to

manufacturer’s recommendations. The resins are placed into the matrix, which is then

seated on the prepared abutment tooth. The temperature is recorded at 30 sec intervals

using the digital thermometer, which read in 0.1 degree C increments. Temperature

monitoring is ceased after it is evident that the peak temperature has been reached.

After complete polymerization of the resin material, the template will be removed from the

tooth and the provisional crown will be retrieved. The procedure will be repeated with the

remaining provisional restorative resin material.

Temperature change for each specimen is calculated

as follows:

Temperature change = Peak temperature noted during the fabrication – Temperature

recorded at the start of provisionalization

Null Hypothesis:

There is no increase in intra-pulpal temperature during fabrication of provisional

restoration by direct method.

STATISTICAL ANALYSIS:

The statistical difference between temperature increase with different provisional

materials and index materials will be tested with analysis of variance (ANOVA) test.

Does the study require any investigation or interventions to be conducted on patients or

other humans or animals? If so, specify briefly

- No, the study will be conducted on extracted molar tooth.

Has the ethical clearance been obtained from your institution in case of the above?

- Not applicable for this study.

LIST OF REFERENCE:

1. Aysegul G. Gurbulak et al “The Effect of Dentin Desensitizer with Different Layers

onThermal Changes on the Pulp During Fabrication of Provisional Restoration.” Journal

of Biomedical Materials Research Part B: Applied Biomaterials, Volume 91B, Issue

1, pages 362–365, October 2009.

2. Driscoll CF, Woolsey G, Ferguson WM. Comparision of exothermic release during

polymerization of four materials used to fabricate interim restorations. J Prosthet Dent

1991;65:504-6.

3. Giuseppe Chiodera et al “Temperature change in pulp cavity in vitro during the

polymerization of provisional resins.” Dental Materials, Volume 25, Issue 3, March 2009,

Page 321-325.

4. Grajower R, Shaharbani S, Kaufman E. Temperature rise in pulp chamber during

fabrication of temporary self curing resin crowns. J Prosthet Dent 1979;41:535-40.

5. Hannig M, Bott B. In-vitro pulp chamber temperature rise during composite resin

polymerization with various light-curing sources. Dent Mater 1999;15:275-81.

6. Jacopo Castelnuovo et al “Temperature rise in pulpal chamber during fabrication of

provisional resinous crowns.” The Journal of Prosthetic Dentistry, Volume78, Issue5,

November1997, Pages441-446.

7. Konstantinos Michalakis et al “Comparison of temperature increase in the pulp chamber

during the polymerization of materials used for the direct fabrication of provisional

restorations.” The Journal of Prosthetic Dentistry, Volume 96 Issue 6, December 2006

Pages418- 423.

8. L. Zach et al “Pulp response to externally applied heat.” Oral surg. Oral Med. Oral

Pathology, Volume 19, 1965, Pages, 515-530.

9. Stanley H. Pulpal response to dental techniques and materials. Dent Clin N Am

1971;15:115-8.

10. Sung-Hun Kim et al “Exotherm behaviour of the polymer based provisional crown and

fixed partial denture materials.” Dental Materials, Volume 20, 2004, 383-387.