Wednesday, March 14, 2018

The continuum of restorative materials in pediatric dentistry – a review for the clinician

NYU Langone Dental Medicine
Resident: Albert Yamoah, DDS                                                                                                                                                          Date: 03/14/2018
Article Title: The continuum of restorative materials in pediatric dentistry – a review for the clinician
Author(s): Joel Berg, DDS, MS
Journal: Pediatric Dentistry
Date: 1998
Major TopicDental materials
Type of Article: Literature Review
Main Purpose: To provide a review of the intracoronal restorative materials used in modern pediatric dental practice
Key Points:
·  Many choices for restorative materials are available to the practitioner of restorative dentistry for children
·  Confusion has been created about what these materials are, making it difficult to identify their appropriate clinical use
·  This paper reviews glass-ionomer materials, resin-modified (reinforced) glass ionomers, compomers and, composite resins
o   Definitions of these materials, a general description of their contents, and usage-selection criteria are provided
Glass Ionomer
·   A salt formed by the reaction between polyalkenoic acid and aluminum containing glass
·   Fluoride in glass material is released over time with a very high fluoride release occurring for a period of several weeks
o   Dissipates to around 10% of original level in 3-4 weeks and then remains at this level for 1 year
·   Has a true chemical bond to tooth structure
·   Coefficient of thermal expansion (COTE) of glass-ionomer is the most similar to tooth structure (mostly dentin)
·   Large difference in the COTE of material and tooth structure leads to failure of the restoration
o   Due to temperature-related expansion/contraction
·   Physical properties of glass ionomers have improved dramatically
o   Due to introduction of high powder-to-liquid ratio glass ionomer materials
o   Denser versions provide a "condensable” feel, facilitating use in posterior teeth

Resin-Modified Glass Ionomers
·   Contain the same components as traditional GICs PLUS resin materials
o   Resin added to provide strength and also the capability to light cure-hydrophilic resin
o   More resistant to fracture
·   Relative amount of resin to glass ionomer in the mixture of RMGI determines physical and clinical behavior of material
o   Being more glass ionomer-like or more resin-like

·   Resin composites with acidic functional groups
o   participate in an acid/base glass-ionomer reaction after the polymerization of the resin molecule has taken place
·   COMPosite + Glass IonOMER = COMPOMER
o   BUT they are not glass ionomer materials
o   A true GI material must be a two-component system, otherwise acid/base reaction occurs immediately
·   With compomers, a resin polymerization takes place, then the material is completely set
·   There must be no water or moisture to prevent a premature GIC reaction
·   The amount of total fluoride released is significantly lower than that of traditional GIC and RMGI
·   Essentially resin composite material
·   Require use of primer before placing

Composite Resin
·   Contains a monomeric or prepolymeric resin that is filled to various levels with glass or quartz
·   Filler particles are silanized (or silanated) to allow the hydrophilic filler to bond to the hydrophobic resin matrix
o   Good silanation is essential for a stable material that is resistant to wear and homogenous in its composition
·   Undergoes polymerization shrinkage.
o   This shrinkage ranges from 2 to 3.5%
o   Causes the composite to pull towards the center of its mass
·   Come in many shades
·   Be aware of both the filler content and size-different clinical indications
o   Filler content is a description of the amount of filler in a composite
o   Filler size is particle size
·   Filler content is merely a description of the quantity of filler in a composite
·   It is generally measured as the weight:weight quantity of filler placed into the resin matrix
o   Expressed as a percent
o   If there is no filler in the resin matrix, the material may be called an "unfilled" resin
§  These materials are used as unfilled sealants, and sometimes as components of bonding agents
o   If the resin matrix is filled approximately 30% by weight, the material may be designated as a "filled" sealant
§  Many sealants are filled to this extent today
§  Some bonding agents are also filled as much or even slightly more (called “filled” bonding agents)

·   Flowable composites are composite-resin materials that are 50- to 70%-filled by weight
·   Highly filled, modern, composite-resin materials are 75- to 85%-filled by weight
o   At this level of filler content, a stiff, easily packable material is achieved
o   Can be used for both anterior and posterior placements
·   Mathematics of adding more filler to resin and measuring the weight:weight filler content percentage:
o   The more filler added, the less the filler content percentage number will rise
o   If a composite is 50% filled, then the filler-to-resin weight ratio is 1:1.
o   If twice the amount of filler exists in a different composite resin, then the filler-to-resin weight ratio is 2:1
·   Filler size is generally expressed as median size (usually the mode as well) of the filler particles within the resin matrix
o   Fillers ground to 5-50 um are referred to as "macrofillers"
o   Fillers that aren’t ground but produced by other procedures and range from 0.01 to 0.1 um are called "microfillers
o   When various mixes of macro and microfillers are created, resultant particle size ranges from 0.5 to 5.0 um
§  Referred to as a hybrid
o   Hybrid materials offer advantage of being suitable for anterior and posterior indications
§  Anterior – polishablity due to microfill
§  Posterior – durability as a result of larger particle size
o   Many clinicians choose to purchase only one material, commonly a hybrid that can be universally used
o   However, to achieve the best esthetic results for anterior restorations, microfilled materials are sometimes preferred

Assessment of Article
·   Level of Evidence/Comments: Level II
·   A good resource to reference contemporary restorative materials

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