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Lasers in Dentistry: Minimally Invasive Instruments for the Modern Practice

Course Number: 394

Erbium Lasers

Erbium lasers are built with two different crystals, the Er:YAG (yttrium aluminum garnet crystal) and Er,Cr:YSGG ( chromium sensitized yttrium scandium gallium garnet crystal). They do have different wavelengths, Er:YAG has 2940 nm and Er,Cr:YSGG has 2780 nm. Though similar, there is a significant water absorption difference between these two wavelengths. Er:YAG wavelength is at the peak of water absorption in the infrared spectrum whereas the Er,Cr:YSGG exhibits approximately one third less absorption. The Er,Cr:YSGG has also been shown to have significantly deeper thermal penetration in tooth structure as well. In general terms they behave similarly and will simply be referred to as erbium lasers.

The erbium lasers are hard and soft tissue capable and have the most FDA clearances for a host of dental procedures. Their primary chromophore is water, but hydroxyapatite absorption occurs to a lesser degree. Photothermal interactions predominate in soft tissue procedures and photodisruptive in hard tissue. Thermal relaxation is excellent and very little collateral thermal damage occurs in tissues when proper parameters are followed.

Tooth preparation is quite efficient with erbium devices and many procedures can be done without local anesthesia. Smear layer is virtually eliminated and the laser has a significant disinfecting effect on the dentin and enamel to be restored. Bone cutting with erbium lasers results in minimal thermal and mechanical trauma to adjacent tissues. Studies have demonstrated the atraumatic effect and excellent healing response following erbium resection of bone.12 Very short laser pulses of 50 to 100 microseconds are typically used for hard tissue procedures.

Erbium lasers are excellent soft tissue devices as well. The main parameters that differ from hard tissue uses are much longer pulse durations (300-1000 microseconds) and less or no water spray. Though slightly more thermal than the hard tissue settings, there still is quite a bit of thermal relaxation and minimal heat penetration into underlying tissues. Consequently, clinicians routinely observe rapid healing with minimal postoperative pain when soft tissue procedures are done with erbium lasers. They can be used anywhere a scalpel is employed including periodontal procedures, gingival contouring, biopsies, frenectomies, pre-prosthetic procedures and the like. Erbium lasers can also be used to safely scale root surfaces during periodontal procedures which has the added benefit of root surface decontamination.25