#4 What I Learned Today

Introduction to Operative Dentistry

The focus of our lecture today was on the operative removal of carious lesions. The preparation and restoration of dental caries is usually dependent on disease progress. Off-coloured lesions that are isolated to the enamel may be treated through prophylactic means such as fluoride treatment, diet modification, or better dental hygiene. However, once a lesion has progressed passed the dentinoenamel junction and into the dentin, restoration intervention is usually necessary. The physiological makeup of dentin differs from enamel, and is much less resistant to the bacterial attack. Carious lesions that progress to the pulp usually need root canal treatment or extraction.

Caries are typically detected through the use of three senses: tactile, auditory and visual. Lesioned dentin tissue typically has a 'tacky' or 'mushy' texture that can be felt through the use of an explorer or spoon excavator. However, the dentist must be careful t0 use light touch in order to avoid damaging enamel that is going through demineralization. When an explorer is contacted with the carious lesion, a 'dull' sound is given off; this differs from the 'tingy' sound one expects from sound tooth tissue. Finally, visual detection of caries can be made. Carious enamel usually has a white/brown/black colour, while carious dentin shows signs of yellow/brown/orange. Generally carious tooth tissue is dull and does not reflect light. One colour exception that needs to be noted is that amalgam sometimes stains tooth tissue a grey colour over time, and this should not be confused with carious tissue. The decision to ultimately perform a restoration should be done based on radiographic evidence and patient history.

Carious removal is performed through the use of a 'target' technique. All stained tissue is removed up to the dentinoenamel junction using a high speed bur, such as the straight fissure bur #256. Next, carious tissue found in the dentin (in this instance, the pulpal and axial floors of the preparation) using the slow speed handpiece with the largest bur possible (typically a round bur such as #2/#4/#6/#8). When nearing the pulp chamber, patient should be made aware of possible exposure, which may result in further treatment.

And of course, all operative dentistry should be done in the mind frame of minimal intervention and maximal tooth conservation.