Minimum Intervention Dentistry (MI) - An Overview Dr S.Mickenautsch, Division of Public Oral Health, University of the Witwatersrand, Johannesburg, South Africa Back MI is a philosophy of professional care, concerned with the first-occurrence, earliest detection and earliest possible treatment of disease on micro (molecular) levels, followed by the most minimally invasive and patient friendly options to repair irreversible damages caused by such disease. MI aims to empower patients (through information, skills and motivation) to be in charge of their own oral health, so that they only require minimum intervention from the dental profession. Based on MI understanding, caries is considered to be an infectious bacterial disease, resulting into lesions of the tooth hard tissues. The disease starts with a disturbance of the oral mineral balance (Remineralization = Demineralization) on the tooth surface. Such changes occur on micro (molecular) level, first. The reasons are assumed to be an increase in bacterial metabolism and subsequent increase of acid production, as well as an increase in bacteria numbers. Contributing factors are an increased intake (in frequency and amount) of carbohydrates (= sucrose) through diet, the absence of fluoride and reduced saliva capacity (flow, buffer, pH). In addition, modifying factors such as changes in lifestyle, general medical conditions, socio-economic circumstances and patient compliance play a role. The caries disease process starts with an oral imbalance and progresses into reversible symptoms (e.g. non-cavitated lesions) first, but extends into irreversible symptoms (e.g. cavitated lesions) with subsequent loss of both tooth structure and (aesthetic, masticatoric, phonetic and biological) functions. The goal of MI is to first stop the disease and then to restore lost structure and function. In order to be able to stop caries, past and present caries experience need to be established. Past caries experience can be assessed from the number of tooth restorations and crowns present; number of extracted teeth due to caries and the number of arrested carious lesions. Present caries experience or activity can be established from the number of white spots, hidden lesions and cavities. Earliest caries detection, traditionally by use of mirror and light, as well as bitewing radiographs is today aided by new innovations in dental magnification and imaging, laser fluorescence and quantitative light induced fluorescence. A new caries classification by site and size of lesions assists in more precise recording and monitoring. A further step is to measure and quantify caries contributing factors, such as bacteria count (chair side tests), saliva characteristics (saliva tests), including examination saliva glands and viscosity. Furthermore, information on dietary habits and absence or presence of fluoride, may assist in detecting further caries risk. A patient interview, within a relaxed atmosphere, may help to establish information on disease modifying factors (medical conditions, life style, socio-economic background and oral hygiene habits), as well as patient’s possible compliance level with future health interventions. All these information complete a comprehensive diagnosis of the disease. On this basis the patient can be effectively motivated to collaborate within the frame of an individual treatment plan. Such plan involves adjustments in modifying and contributing factors, as well as in the treatment of the bacterial infection. MI treatment on micro- or molecular levels starts with controlling the bacterial infection and to heal reversible carious lesions. Carious infection can be controlled with a wide range of treatment methods, involving Chlorhexidine, Diammine silver fluoride, Ozone application, Triclosan, Fluoride and effective cavity seal by chemical material adhesion. Antibacterial treatment is aided by adjustments of contributing factors, such as reduction of amount and frequency of sucrose intake, access to fluoride, increase of saliva buffer function, -flow and pH, as well as to increase mineral supply through supplements (Casein phosphopeptide / Amorphous calciumphosphate complex – CPP/ACP).  After the infection, the loss of minerals from tooth hard tissues trough remineralisation (lesion healing) needs to be addressed and the oral balance regained. This is done on the tooth surface through ‘external remineralisation’ and on cavity walls through ‘internal remineralisation’.  In general, remineralisation depends on the presents of water, a pH > 6.5 and the availability of minerals, such as Calcium, Phosphate and Strontium. External remineralisation relies on the increase of saliva flow through fluid intake and use of dental chewing gum, an efficient oral hygiene and diet adjustment, as well as the use of dentifrice containing CPP-ACP or Fluoride, respectively. Internal remineralisation relies mainly on the use of a therapeutic filling material. Such material needs to be hydrophilic, provide a good seal (by chemical adhesion) and have a high mineral and fluoride content. These characteristics are not necessarily consistent with the physical requirements for a long term filling material thus therapeutic materials can be of temporary nature, to be replaced by stronger materials at a later stage. For this purpose, therapeutic materials should be easily identifiable in vivo by color or shade. During this period of caries treatment, repeated recalls for diagnostic measurements and monitoring are required.  Treatment should continue until the bacterial infection is controlled and reversible carious lesions are healed. Once ‘absence of disease’ is achieved, the irreversible loss of structure and function is addressed using minimally invasive, patient friendly treatment options. Minimally invasive treatment comprises of aspects in cavity preparation (e.g. air abrasion, laser treatment and sono-abrasion) caries removal (e.g. Selective caries removal, Laser treatment) and cavity restoration (e.g. Atraumatic restorative treatment, Preventive resin restoration, Sandwich restorations). Restorations are usually small and rendered relative painless. If procedures under local anesthetic are needed, they can be administered using computer controlled local anesthetic delivery systems. Failed restorations are repaired rather then replaced. The philosophy of Minimum Intervention Dentistry as described above, is based on a wide range of new innovation, technologies and treatment methods. Furthermore, the volume of published studies is increasing. However, with the dawn of new philosophies and publications a systematic and comprehensive appraisal, following evidence-based principles in dentistry is needed. References: ·    Tyas MJ, Anusavice KJ, Frencken JE, Mount GJ. Minimal intervention dentistry--a review. FDI Commission Project 1-97. Int Dent J. 2000 Feb;50(1):1-12. ·    Mount GJ, Ngo H. Minimal intervention: a new concept for operative dentistry. Quintessence Int. 2000 Sep;31(8):527-33. ·    Mount GJ, Ngo H. Minimal intervention: early lesions. Quintessence Int. 2000 Sep;31(8):535-46. ·    Mount GJ, Ngo H. Minimal intervention: advanced lesions. Quintessence Int. 2000 Oct;31(9):621-9. Back