Posterior Composites

ALLAH’S Thought at all times

Fazal ur Rehman Qazi

BDS, FCPS.Asst. Professor Operative Dentistry

DIKIOHS,DOW UniversityKarachi

What is Nanotechnology

An emergent science formed from the convergence of chemistry (classically restricted to atomic interaction) and molecular scale physics and biology

(previously restricted to the micron scale)

Dental update Jan-Feb 2003

Nanofilled Composites

• Handling• Easy finishing and polishing

• Durability

Preparation for Posterior Composite Restorations

Centric occlusal stops located primarily on tooth

structure

Excessive tooth wear from clenching or grinding

Esthetics as a prime consideration

Cavosurface margins in enamel

Follow Directions For Use

Contamination

• Biofilm• Gingival Exudate• Saliva • Blood• Eugenol• Handpiece Oil

No special Preparation for Class 1 Composite

Restorations

Margins of the Occlusal Preparation should not be Bevelled

Class 2 Composite Restorations

Prewedging

Beveling for facial and lingual margins of the

proximal box

Gingival Margins

Occlusal Margins

Placement of occlusal bevels has

demonstrated no benefit to the

longevity of class 2 resin composite restorations

Cavity Liners with Composite Restorations

Calcium- Hydroxide Liner

Glass-ionomer Liners

• Improve marginal integrity and decrease marginal leakage (J Dent 1993;21:158-162)

Reduce polymerization shrinkage and cuspal deformation(Quintessence Int 1988;19:191-1980

• How should composite be layered to reduce shrinkage stress: Incremental or bulk filling? . (Dental Materials 2008 ; 24 :1501 – 1505)

Glass ionomer liners

• SEM and microleakage evaluation of the marginal integrity of two types of class V restorations with or without the use of a light-curable coating

• J Dent. 2008 Nov;36(11):885-91. Epub 2008 Aug 30 material and of polishing.

Dental Composites are much stronger than the liners and bases and are equally insulating

JADA 1994;125:687-701

Investigation of the electrical properties of some dental composite restorative materials before and after laser exposureDental materials 2005 ;vol 22 : 885 - 895

Use of glass ionomer liner on dentine cavity surfaces has shown to significantly reduce postoperative sensitivity

Am J Dent 2001;14:34-38

Bonded Base Technique

Techniques to make tight contacts

• Use of thin sectional matrices• Prewedging• Prepolymerized composite balls• Special wedge shaped composite curing tips.

Do you need to use flowable composite under posterior composite restorations?

The Snow Plow Technique

Improvements in Dentine Bonding Systems

The wet bonding technique has been repeatedly shown to enhance bond strengths

Quintessence Int 2001;32:385-390

Nanotechnology Dental Adhesives

Incorporation of organic solvents like acetone or ethanol

Dentine is air dried collagen fibres collapse

Depending on cavity size, dispense 1 or 2 drops of XENO V into a DENTSPLY CliXdish™.

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In a closed CliXdish XENO V remains useable for up to 30 minutes. Disassemble for cleaning and disinfection.

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Apply XENO V twice, wetting all cavity surfaces uniformly with each application.

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Then gently agitate the adhesive for 20 seconds.

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Evaporate solvent by thoroughly blowing with air for at least 5 sec. Avoid pooling.

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Cure for at least 20 seconds.

Min. Output Halogen ≥ 500 mW/cm2 Min. Output LED ≥ 800 mW/cm2

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Place increments

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INCREMENTAL TECHNIQUE

• Shrinkage results in interfacial stresses, with the potential for debonding and/or local fracture of tissue or restorative.

• Shrinkage should be minimised as far as possible.

Shrinkage

Light-cure each increment (4 mm)

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* 10 sec for light output ≥ 800 mW/cm2, 20 sec for light output of 500 to 800 mW/cm2.

Polishing can be done immediately

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Clinical Case

Clinical Case

Core Buildup (Pre-Op)

Core Buildup (Post-Op)

Wear Resistance

• Clinical Relevance: A low wear rate means that enamel-restorative margins and contact points remain at the correct level, and that gross loss of material does not occur. It goes without saying that a low wear rate is a prerequisite for a modern composite.

Flexural Strength and Modulus

Clinical Relevance: The flexural strength of a dental material is an important property since materials may be used in thin layers or in poorly supported edges where flexural forces occur.A high flexural strength is therefore needed.