Fundamental Principles of Anterior Tooth Preparation and Restoration

Class III preparation/restoration

-preparation/restoration involving the proximal surface of an anterior tooth without involving the incisal angle

-involves smooth enamel surfaces

-most often start to form just apical to the contact area

class III preparation/restoration location

-will always be on the mesial or distal of a tooth and may involve the facial surface, lingual surface, or both

-if the caries can be accessed from the lingual and the facial surface be left intact, this is preferable

-sample terminology: #8-ML, #7-DL, #6-MLF, #10-DLF

Class III preparation

-bur is directed perpendicular to the enamel surface

-initial cut is made in the center of the contact area and extended gingivally until contact is broken

-incisal and gingival proximal walls are perpendicular to the root and form an approximately 90 degree angle to the tangent of the tooth surface

class III preparation outline form

-external outline form is rectangular, approximate axial width and facial depth of 1.7-2mm

-preparation should stay within the confines of the marginal ridge

-clinically, the shape and depth is dictated primarily by the extent of the caries

-preferred bur is a 330 carbide, 0.8mm diameter and 1.6mm length

operator positioning

-12 o’clock is preferred seating position for the maxillary lingual surfaces

-finger rests are positioned on the teeth adjacent to where you’re working

-visualization is through indirect vision

class III composite restoration steps

1) shade selection

2) isolation

3) tooth etching, priming/bonding

4) placement of composite

5) finishing and polishing

class III composite restoration steps- shade selection

-should be done before isolation and preparation of the tooth because dehydrated teeth become lighter and lose their natural translucency

-incisal 1/3s of teeth (mostly enamel) are lighter and more translucent than the cervical 1/3s (mostly dentin)

-shade selection is preferably done under natural light and an appropriate shade guide should be used

-for anterior teeth in particular, it can be helpful to place composite on the unetched tooth prior to isolation to check the shade match

class III composite restoration steps- isolation

-appropriate isolation must be confirmed before restoration placement

-for anterior teeth, the rubber dam is placed from canine to canine and a clamp is usually not needed

-rubber dam may be ligated distal to the canines with floss or small piece of rubber dam

class III composite restoration- tooth etching, priming/bonding

-for composite restorations, the tooth must be etched and a priming/bonding agent must be placed and cured

-various techniques exist for etching, priming, and bonding

class III composite restoration- placement of composite

-either a syringe or hand instrument can be used for placement

-syringe technique convenient method and reduces the possibility of trapping air, but control of the amount of composite injection must be developed

-composite placed in increments to ensure complete curing and to reduce overall polymerization shrinkage

-composite should be placed with a “jiggling” motion to prevent air incorporation and voids

-use of a mylar matrix band and wedge is critical to achieve appropriate contour and contact, and to prevent overhand in class III restorations

-mylar matrix band should be cut to be approximately 1 inch long

-careful holding of the matrix band to mimic the interproximal contour while curing is critical for a good result

-condenser/plastic instrument

placement of composite- depth of cure

-composite has a maximum cure depth of 2.5mm; composite should not be placed in increments greater than 2.5mm

-each increment should be cured for at least 20 seconds with the curing light being held as close to the restoration as possible

-LED curing light with a narrow spectrum of blue light in the 400-500nm range which initiates photo-polymerization

-ambient light and operatory light will cure the composite material

-curing occurs through the mylar matrix band for class III and IV restorations

composite restoration steps- finishing and polishing

composite restoration evaluation- class III composite restoration must

-have contact

-have appropriate proximal and lingual contour

-be free of gingival overhang

-not have any excess composite present outside of the cavo-surface margin on unprepared tooth structure

-be smooth and free of voids

class IV preparation/restoration

-preparation/restoration involving the incisal angle of anterior teeth

-can be result of fracture or caries that extends to the incisal angle

-involves smooth enamel surfaces

-examples: #8-MIFL, #9-DIFL

class IV considerations

-a bevel or chamfer can be created to increase enamel surface area and increase the number of ends of enamel rods for bonding

-allows for increased retention and an esthetic transition from tooth structure to composite

-class IV preparation with chamfer

class IV restoration

-a mylar matrix band and wedge are again used

-a lingual wall, facial wall, incisal edge, and proximal wall must be created

-can be done free hand or with a stent

-a knowledge of anatomy is critical and the tooth must be evaluated from all aspects

anterior restoration tips- mylar matrix band

-make sure the mylar matrix band is no longer than 1 inch

-contouring the band with a blunt instrument handle can help with proper adaptation of the band

-mylar matrix bands are thin and can normally easily pass between two teeth; if any difficulty is experienced, a wedge can be placed to slightly separate the teeth and allow for ease of placement

anterior restoration tips- wedge

-careful consideration should be given to choosing the right size wedge; wedge must fit securely and the apex of the wedge should ideally end at the gingival cavosurface margin

-a wedge that is too large may cause unnatural separation of the teeth leading to an overbulked restoration or an unnatural gingival embrasure space

-a wedge that is too small will not securely hold the matrix band and will not compensate for the slight thickness of the band and may also lead to gingival overhang

-wedge can be tried in and fit prior to placement of the mylar matrix band and then removed and refit with the matrix band in place

anterior restoration tips- placement

-an ideal class III preparation will require no more than 2 composite placement increments

-make sure that placement instrument is clean, dry, and free of debris; modern composites will not stick to an instrument that is clean and dry if proper placement technique is followed

-make sure the composite is protected from ambient light during the placement process

-placement of a slight excess of composite is OK for the final increment before the matrix band is adapted as this well ensure the seal of all margins; slight excess is removed during the finishing process

-operator must carefully close the matrix band around the final composite increment with the thumb and index finger

-care must be taken to make sure the band is properly contoured against the tooth and composite during this step; tooth should be your guide

-composite cured through the mylar matrix band

anterior restoration tips- finishing and polishing

-always use the existing tooth structure and your knowledge of dental anatomy as a guide for finishing and polishing

-use a constant brush like motion to avoid creating a flat or under contoured restoration

-be careful to not place an excessive amount of composite; removal of excess composite is very difficult and time consuming

-slight excess lingual composite can be removed with a football or oval shaped finishing bur; excess in the incisal embrasure and facial surfaces can be removed with a flame shaped finishing bur

-finishing strips can be used for interproximal surfaces; do not overuse and create an open contact

-abrasive discs in sequential order (start disc depends on amount of composite that needs to be removed) create a smooth surface

-discs can also help create incisal embrasure form; discs can be used for finishing or polishing

-polishing points, cups, and discs can be used on all accessible surfaces