106 - Dental Practice September/October 2006 T he advent of the acid-etch technique by Buonocore in the 1950’s and 60’s brought about an enormous change in clinical operative dentistry. No longer was it necessary to prepare a tooth to adapt to the limitations of the amalgam restorative material. 1 Using existing tech- nologies such as CPP-ACP (Recaldent ™ ) and fluorides, smooth surfaces of dem- ineralized enamel can be remineralized, while glass ionomers can interact chemically with the affected dentine (the softened, non-infected demineralized layer) in the depth of the cavity and drive remineralization. Areas of unsup- ported enamel can be supported with adhesive restorative materials and margins do not have to be extended into theoretically “caries-free” areas. A rem- ineralizing material such as glass ionomer cement can be laminated with another material such as composite resin, to better withstand masticatory stresses of the oral environment. 2 This has been termed the “Sandwich Restoration”. Minimal clinical cavity access can be defined as the least amount of enamel removal required to enable adequate access for visualisation and removal of the infected dentine. This is best accom- plished with the use of magnification as this greatly aids the preservation of tooth structure. Use of binocular loupes should almost be considered a pre- requisite for carrying out sound minimally invasive dentistry. Micro-preparation techniques Micro-preparation techniques can involve a number of cutting modalities: • Micro-preparation and fissurotomy burs; • Sonic tooth preparation; • Air abrasion; • Chemomechanical methods; and • Lasers. Micro-preparation and fissurotomy burs Many manufacturers are now producing smaller burs for cavity preparation using MI techniques. The burs are spherical, tapered or elliptical. Examples include fis- surotomy burs (SS White, USA) and narrow diamond burs (Brassler, USA). Used with the aid of magnification, these allow very precise preparation of teeth. Micropreparation burs allow the dentist to conservatively explore and modify the fis- sures even when caries has spread laterally along the dentinoenamel junction. Sonic tooth preparation This utilizes the vibrational energy of ultrasonically vibrated metal tips, rather than rotation. It allows precise minimal cutting preparation using diamond coated tips, such as those of the SonicSys system (KaVo, Biberach, Germany). Air abrasion This utilizes a stream of small (27.5 micron diameter) aluminium oxide particles under air pressure to remove tooth substance by brittle fracture (Figure 1). It produces less heat, sound or vibration compared to high speed instrumentation and does not induce microfractures or microcrazing that follows high speed instrumentation. 3 Air abrasion can be used for: • Cutting small pit and fissure cavities; • Removal of composite and porcelain; • Clean and prepare tooth surfaces of debris, metal, porcelain and composite prior to adhesive restoration; and • Minor class II, class III, class IV and class V cavity preparations. Minimally invasive operative techniques using high tech dentistry BY DR ANDREW M. BROSTEK DR ANDREW J. BOCHENEK PROF . LAURENCE J. WALSH HIGH TECH DENTISTRY Figure 1. A KaVo air abrasion tip utiliz- ing additional water spray for decreased patient sensitivity. Figure 2. Use of mechanical hand instrumentation with Carisolv. Courtesy Mediteam Dental, Gothenburg, Sweden. Figure 3. The Carisolv gel in a 2-compo- nent syringe, with specifically designed hand instruments.