New Advances in Caries Removal

Dr Wael Al-OmariBDS, MDentSci, PhD

Caries Removal

Drawbacks of Conventional Methods: Contamination and cross-infection The need for presterilisation cleaning. 1-Manual cleaning of burs 2-Washer disinfection. 3-Ulrasonic cleaners with enzymatic detergents Removal of infected and unaffected tissues. - Is total caries removal necessary? Noise, vibration and discomfort experienced with

burs.

Rational behind New Developments

Removal of only infected dentin Reduce patients anxiety Provide favorable surface features for bonding Reduce contamination and cross-infection Reduce the need for anesthesia Easier recognition between infected and

uninfected dentin Provide equal or superior efficiency compared

to conventional methods Reduce cost.

New Developments in Caries Removal

Lasers Air Abrasion (Kinetic Cavity Preparation) Polymer Burs Micropreparation Burs. Photoactivated Disinfection Carisolv Gel Atraumatic Restorative Treatment. Caries-Detector Dyes

Lasers Early Lasers (Caron dioxide, ruby and

Nd:YAG): 1- Inefficient cutting 2- Excessive heat generation 3- More efficient for soft tissue surgery.

Nd:YAG laser ablated dentin showing craters and cracks and heat induced

band (Lin et al, 2001)

Erbium Lasers

Erbium yttrium aluminum garnet (Er:YAG, 2.94 µm wavelength)

Erbium chromium yttrium scandium gallium garnet (Er,Ch:YSGG, 2.78 µm wavelength)

Mechanism of ablation by erbium lasers

Thermomechanical Ablation - High absorption coefficient in water and high

affinity for hydroxyapatite. - Absorbed heat cause microexplosions and microfragmentataion of target issue. - Irradiated surface demonstrate microirregularities, absence of smear layer, open tubules, absence of extensive thermal effects.

Cavity prepared with erbium laser

Bur cut versus Er,ch:YSGG laser cut dentin (Ekworapoj et al, 2007)

Advantages of erbium lasers

No thermal effect on target tissues and pulp.

Noiseless, no vibrations. No harmful effect on the pulp. Distinguishing between infected and

uninfected dentine might be possible. Various clinical applications:

periodontics, endodontics, operative dentistry.

Disadvantages of erbium lasers

Cost Erbium laser preparations must be

followed by acid etching for reliable bonding to resin composite

May weaken the irradiated surface (lower microhardness) Defocusing effect due to water spray Tissues can be only removed when it is

visible to operator’s line of sight. Lack of tactile sensation Large devices

Waterlase MD Biolase ezlase 940

Future Development

New more efficient generations of erbium lasers.

Lasers with femtosecond pulse duration (pulse duration = 10-15 s)

Air Abrasion (Kinetic Cavity Preparation)

This technique uses a pressurized stream of small aluminum oxide particles to abrade carious lesion.

Typical Air Abrasion system: - Particle diameter 27-50 µm.

- Powder flow rate 0.7-4.2 g/min - Air pressure 40-160 psi - Operating distance from tooth 0.5-2 mm

Air abrasion Handpiece

Air Abrasion Unit

Clinical Indications

Removal of superficial enamel defects For detection pit and fissure caries by removal of

organic debris. Removal of enamel surface stains. Removal of localized minimal carious lesion Surface preparation of abfractions and abrasions

to brake the glaze of the surface for better bonding.

Removal of existing restorations. The need for anesthesia may be avoided

because of the cooling effect of the high pressure air

Cavity prepared using air abrasion technique

Advantages of Air Abrasion

Less painful than bur preparation due to less noise and vibration.

More conservative than bur for minimal fissure and pit caries.

Roughened surfaces may favor better bonding….However air abrasion is not a substitute for acid etching

Limitations of Air Abrasion

There is little tactile sensation Unable to remove gross caries. Removes normal and relatively hard dentin. Remove exposed cementum and root dentin. Splattering f powder-risk of ingestion. Unable to prepare well-defined cavity margins. Does not obviate the need for acid etching. May lacerate soft tissues Removal of large amalgam causes release of

mercury Mandatory need for rubber dam, high velocity

evacuation and protective eyewear

Future Developments in Air Abrasion

Less abrasive powders - Softer particles may be more effective in selective removal of carious dentine

Polymer Bur Described by Boston (2000). Made of a softer polyamide/imide polymer

material. Remove infected dentine only Manufacturer: SmartPrep (SS White, USA) Harder than carious dentine and softer than

healthy dentine Designed for single use on slow-handpiece Remove caries from central of lesion to

periphery Less effective than carbide bur in caries

removal (Dammaschke et al, 2006)

Polymer burs SmartPrep before (1a) and after (1b) use (Dammaschke et al, 2006)

Micropreparation Burs Fissurotomy Burs (SS White,USA) allow

exploration of the fissures with minimal removal of enamel.

It is 1.5-2.5 mm in length and tapers to fine carbide tip.

Other burs such as Brassler 889M-007 bur and Microdiamond 838M-007 burs are used for minimal preparation.

Microinstruments (Micropreparation set) requires low contact pressure (< 2N)

Fissurotomy Bur

Conventional bur versus fissurotomy bur

Photoactivated Disinfection The system use disinfectant solution

applied to deep caries, allowed to penetrate softened dentin for 60 s, and then photoactivated with low-powered diode laser for 1 min.

Dilute toluidine blue binds to bacteria. Red light activation release oxygen that kills the cells

Healthy tissues are not damaged by the laser

Toluidine blue is safe at the used dilution

Toludine blue and laser acts together effectively.

Photo-Activated Disinfection (PAD)

Carisolv Gel Carisolv s a chemomechanical method

for caries removal. It is a mixture of amino acids and 05%

sodium bicarbonate The resultant high-pH chloramines

reacts with denatured collagen in carious dentin

Softened dentin is removed with special hand instruments

Special hand instruments used with Carisolv Gel

Clinical Indications For Carisolv Gel

Removal of root and coronal caries where access is easily obtained

Due to selective removal of carious dentine, the need foe anesthesia is reduced , thus the technique is indicated in children, dental-phobic patients and special needs patients

Advantages of Carisolve Gel Selective removal of carious dentine. The reduced need for anesthesia Does not affect the bonding to

composite. Removes smear layer Does not cause adverse effect on the

pulp.

Disadvantages of Carisolv Gel

Technique requires longer time than conventional method.

May be inefficient for removing caries at enamel-dentin junction.

Caries under overhanging enamel may go unnoticed.

Large lesions needs to be accessed using rotary bur.

NِAtraumatic Restorative Treatment (ART

Atraumatic Restorative Treatment is a procedure based on removing carious tooth tissue sing hand instruments alone and restoring the cavity with an adhesive restorative material namely glass ionomer

Hand instruments used in ART

Reasons for using hand instruments in ART

Makes restorative procedure accessible to all population.

Minimal cavity preparation Low cost Reduce need for anesthesia Simplified infection control due to

easy cleaning and sterilization

Reason for using glass-ionomer in ART

Glass ionomer sticks chemically to enamel and dentin

Fluoride release Compatible to oral and hard dental

tissues

Advantages of ART

Benefit the less-industrialized and deprived communities

Minimal invasion preparations Friendly procedure for children,

fearful adults, physically or mentally handicapped, people living in nursing homes and the home-bound elderly

Disadvantages of ART

Restorations tend to fail and wear. Incomplete removal of bacteria Wear and failure means that

patients require frequent review by trained personnel

Difficult o remove caries in inaccessible lesions.

Caries Detection Dyes Dyes such as 1.0% acid red in propylene

glycol. They stain infected dentine and organic

matrix of demineralised of carious dentin that should not be removed.

They stain dentin naturally with low minerals such as circumpulpal dentin and enamel-dentin junction

Result in overpreparations. Not useful in detecting pt and fissure caries

because they stain food debris and other organic materials in the fissure

They are not recommended

Caries detecting dyes stains demineralised matrix of carious dentin that should not be removed