M.Sc. STUDY

The Effect of Type and Mode of Light Curing Units
on Microleakage of Resin Based Composite Restorations

M.Sc. Awarded in 2007

Shedding Light on Microleakage: My Master's Thesis on Light Curing

During my Master's studies in Dentistry at the University of Mosul, I was fascinated by the intricate relationship between light curing units and the success of composite restorations. This fascination led to my thesis research, titled: "The Effect of Type and Mode of Light Curing Units on Microleakage of Resin Based Composite Restorations."

Microleakage, the seepage of fluids along the margins of a restoration, is a major concern. It can lead to sensitivity, recurrent decay, and even pulp damage. My research explored how different light curing units and curing modes influence microleakage in composite restorations.

Traditional vs. Modern Light Curing:

Traditionally, halogen light curing units (LCUs) have been the workhorse for curing composite materials. However, they have limitations like a short lifespan and diminishing effectiveness over time.

This project investigated Light Emitting Diode (LED) LCUs as a potential alternative. LEDs offer advantages like a longer lifespan and a more consistent light output. The research also compared different curing modes, including "soft-start" techniques designed to minimize shrinkage stress.

Promising Results for Improved Restorations:

The findings of my thesis were encouraging. LED LCUs demonstrated significantly less microleakage compared to conventional halogen LCUs. Additionally, the "soft-start" technique, employed with both LED and halogen units, resulted in less microleakage compared to continuous-mode curing.

A Stepping Stone for Better Care:

This research represents my early dedication to evidence-based dentistry. By understanding the impact of light curing on restorations, we can strive for better outcomes and improved patient care.

Interested in Learning More?

If you'd like to delve deeper into the specifics of this research, including the materials, methodologies, and detailed results, you can access the full text of my Master's thesis: [Link to view MSc Thesis].

This research laid the foundation for my ongoing exploration of dental materials and techniques. I am committed to continuous learning and innovation for the benefit of my patients.

QUALIFICATION DETAILS:

M.Sc. Thesis Details:

TITLE: The Effect of Type and Mode of Light Curing Units on Microleakage of Resin Based Composite Restorations

AUTHOR: Bahar Jaafer Hajee Omer Al-Selivany, [B.D.S.]

ISSN:

AWARDING BODY: The College of Dentistry, The University of Mosul

CURRENT INSTITUTION: The University of Duhok

DATE AWARDED: 2007

Full Text Link: [PLEASE CLICK TO VIEW THE FULL TEXT OF MY M.Sc.]

SUPERVISOR: Prof. Dr. Jabbar Hussain Kamel

SPONSOR: The University of Duhok and The University of Mosul

QUALIFICATION NAME: Degree of Master of Science in Conservative Dentistry

QUALIFICATION LEVEL: M.Sc.

LANGUAGE OF THE THESIS: English

REPOSITORY LINK:

Citation to this work:

Selivany, BJ, (2007), The Effect of Type and Mode of Light Curing Units on Microleakage of Resin Based Composite Restorations, M.Sc. Thesis, The University of Mosul,

Abstract:

The clinical performance of light polymerized resin-based composites (RBCs) is greatly influenced by the quality of the light curing unit(LCU). A commonly used unit for polymerization of RBCs material is the Halogen LCUs. However, they have some drawbacks. Development of new blue super bright Light emitting diodes (LED LCU) of 470 nm wavelengths with highlight irradiance offers an alternative to standard halogen LCU.

The aim of this in vitro study is to compare the effectiveness of LEDLCUs ; LED High intensity (radii SDI, Australia) which emits 1200mW/cm², LED Low intensity (LED Top Light, Taiwan) which functions in three modes, Fast, Ramp, and Pulse that emits 330 mW/cm², Quartz Tungsten Halogen (QTH LCUs) in soft start mode (Degussa® Soft – Start, Germany) which emits 250 mW/cm² in the first 10 seconds of curing and 450mW/cm² for the following 30 seconds of curing, and conventional QTH LCU (Astralis 5 Viva dent) in standard mode which emits 540 mW/cm² in continuous mode on the microleakage of class V cavities.

For microleakage evaluation, class V cavities were prepared on buccal and palatal surfaces of 84 freshly extracted non-carious, crack free upper premolars.

The teeth were randomly divided into two main groups (42 teeth foreach main groups), one main group filled with hybrid composite (Filtek Z250, 3M ESPE) and the second main group filled with microfilmed composite(Heliomolar® HB) according to manufacturer instructions.

Then each main group was randomly divided into six subgroups:

Group one : the composite was cured with LED Fast mode LCU.
Group two : the composite was cured with LED Ramp mode LCU.
Group three : the composite was cured with LED Pulse mode LCU.
Group four : the composite was cured with LED High intensity LCU.IV
Group five : the composite was cured with QTH in soft start mode LCU.
Group six : the composite was cured with conventional QTH LCU.

After the teeth were filled, they were stored in normal physiological saline for one week in anincubator at 37 Cº. All the specimens were thermocycled for 150 cycles at 5 and 55 Cº with 20 seconds dewell time.

The apices of the teeth were then blocked with cold cure acrylic resin and the teeth were coated with two layers of nail varnish except one mm around the restorations. The teeth were then immersed in 0.2 % methylene blue solution for four hours, washed and sectioned longitudinally (Buccolingually) and the extent of the dye penetration was analyzed by Stereomicroscopy.

Analysis of variance one way (ANOVA) test, The Least Square Difference (LSD) test, unpaired t-test, Two way analysis of variance (ANOVA) test were used for statistical analysis, and difference was considered significant at P ≤ 0.05.

The result of this in vitro study showed that the LED LCUs revealed better results compared to conventional QTH LCU with significant difference from it.

The soft-start polymerization technique with both LED LCUs and QTH LCU revealed less microleakage scores than conventional QTH LCU in continuous mode, with significant difference from it.

Filtek Z 250 hybrid composite showed less microleakage when compared with the Heliomolar micro-filled composite resin, although it was statistically not significant.

The conclusion of this in vitro study showed that LED LCU performed less microleakage comparing with conventional QTH LCU and Soft – Start polymerization technique for both LED LCUs and QTH LCU showed less microleakage comparing to conventional QTH LCU.

Keywords:

Microleakage, Light Curing Units (LCUs), LED LCUs, Soft-Start Polymerization, Resin-Based Composite Restorations

Reference List:

ADA Protocol guidelines for dentin and enamel adhesive materials (1993) Council on dental materials. Chicago, USA.
Aguiar FHB, Ajudarte KF, Lovadino JR (2002) Effect of light curing mode sand filling technique on microleakage of posterior resin composite restorations. Oper Dent ; 27: 575-562.
Alani AH and Toh CG (1997) Detection of microleakage around dental restorations: A review. Oper Dent; 22: 178-185.
Al-Sharif KZ (2001) The relationship between cure depth and absorption coefficient of visible light activated resin composites. Thesis, University of Baghdad.pp: 63-64.
Alexander UHI, Mills RW, Rzanny AE and Jandt (2005) Time dependence of composite shrinkage using halogen and LED light curing. Dent Mater;21: 278-282.
Althoff O and Hartung M (2000) Advances in light curing. Am J Dent; 13:77D-81D ( PubMed citation ).
Al-Turki M and Akpata ES (2002) Penetrability of dentinal tubules in adhesive –lined cavity wall. Oper Dent ; 27: 124-131.
Arikawa H, Fuji K, Kanie T, Inou K (1998) Light transmission characteristics of light-cured composite resins. Dent Mater; 14:405411.
Artermis A and Karamka B (1985) Microleakage of composite resin restoration with cementum margins. J Prosth Dent; 53: 361-364.
Asmussen E and Peutsfeldt A (2001) Influence of pulse delay curing on softening of polymer structure. J Dent Res; 80:1570-1573.
Atmadja G and Bryant RW (1990) Some factors influencing the depth of cure of visible light activated composite resins. Aus Dent J; 35:213-221.
Bala O, Ölmez A, and Kalayci S (2005) Effect of LED and Halogen light curing on polymerization of resin-based composite. J Oral Rehabil; 32:134-143.
Barghi T, Berry T and Hatton C (1994) Evaluating intensity output of. Curing lights in private practice, J Am Dent Associ; 25: 992-996.
Bassionny MA and Grant AA (1978) A visible light-cured composite restorative. Br Dent J, 145: 327-330.
Bayne SC, Thompson JY and Swift JR (1998) A characteristic of first Generation flowable composite. J Am Dent Assoc; 129: 567-577.
Bayne SC, Thompson JY and Taylor DF (2002) Dental Materials In :Roberson TM, Heyman HO, and Swift EJ, Sturtevant's Art and Science of Operative Dentistry. 4th ed., St. Louis, Msby Co., Ch.4 190-191.
Baum L, Philips R and Lund M (1995) Text book of Operative Dentistry. 3rded. WB Saunders Company. Ch. 9 : 220-230.
Blankenau RJ, Kelsy WP, Powell GL, Shearer GO, Barkmeier WW, Gavel WT (1991) Degree of composite resin polymerization with visible Light and argon laser. Am J Dent; 4: 40-42.
Blankenau RJ, Kelsey WP and Kutsch VK (1995) Clinical application of argon laser in restorative dentistry In : Miserendino LJ and Pick RM :Laser in dentistry. Quintessence Publishing, pp : 217-230.
Blankenau RJ, Erickson R and Rueggeberg FA (1999) New light curing options for composite resin restorations. Compendium; 20: 122-129.
Brackett WV, Haisch LD and Covey DA (2000) Effect of plasma arc curing on microleakage of class V resin-based composite restorations. Am J Dent; 13: 121-123.
Bruning GL and Knitz BL (1977) Computational handbook of statistics.2nd ed. Scott, Froseman & Company. Illinois, pp 67.
Caughman WF, Rueggeberg FA and Curtis JW (1995) Clinical quid lines for photo curing restorative resins. J Am Dent Assoc; 126: 1280-1286.