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The traditional period

In the late sixties, composite resins were introduced as an alternative to silicates and unfulfilled resins, which were frequently used by clinicians at the time. Composite resins displayed superior qualities, in that they had higher mechanical properties than silicates and unfulfilled resins. Composite resins were also seen to be beneficial in that the resin would be presented in paste form and, with convenient pressure or bulk insertion technique, would facilitate clinical handling. The faults with composite resins at this time were that they had poor aesthetics, poor marginal adaptation, difficulties with polishing, difficulty with adhesion to the tooth surface, and occasionally, loss of anatomical form.

The microfilled period

In 1978, various microfilled systems were introduced into the European market. These composite resins were appealing, in that they were capable of having an extremely smooth surface when finished. These microfilled composite resins also showed a better clinical colour stability and higher resistance to wear than conventional composites, which favoured their aesthetic appearance as well as clinical effectiveness. However, further research showed a progressive weakness in the material over time, leading to micro-cracks and step-like material loss around the composite margin. In 1981, microfilled composites were improved remarkably with regard to marginal retention and adaptation. It was decided, after further research, that this type of composite could be used for most restorations provided the acid etch technique was used and a bonding agent was applied.

= Common antibiotics used in Dentistry = Phenoxymethyl Penicillin (https://en.wikipedia.org/wiki/Penicillin): Penicillin-based antibiotics are used commonly against a broad range of bacterial infections within the body, primarily due to non-toxic effects and minor side effects. In dentistry, phenoxymethyl penicillin is used as it is acid-resistant and can be administered orally. Its common uses include treatment against acute oral infections such as dental abscesses Oral Microbiology fifth edition, Philip D Marsh, Michael V Martin-Page 153, pericoronitis https://en.wikipedia.org/wiki/Pericoronitis, salivary gland infections and post-extraction infection. The main disadvantage however, is that patients can be allergic to penicillin based materials with a severe anaphylactic reaction occurring. Despite this, it is still commonly used due to it being highly cost effective and relatively safe. Alternative antibiotics include Erythromycin, cephalosporin and several others. Clinical oral microbiology-T.Wallace Macfarlane, Lakshman P. Samaranayake. Page 212-13

Tetracycline ( https://en.wikipedia.org/wiki/Tetracycline ): A wide spectrum antibiotic used to treat multiple bacterial infections. If prescribed during permanent tooth eruption in the mouth, grey staining can occur on the erupting teeth, presenting as a grey band at the point of eruption. The severity of the stain can vary depending on the level of intake of tetracycline. In the UK, there are restrictions on when tetracycline can be prescribed as this staining can be quite severe. ( https://en.wikipedia.org/wiki/Tooth_whitening ) http://www.bowriverdental.ca/cochrane-dental-services/cosmetic-dentistry/teeth-whitening/ Rajendran A; Sundaram S (10 February 2014). Shafer's Textbook of Oral Pathology (7th ed.). Elsevier Health Sciences APAC. pp. 386, 387. ISBN 978-81-312-3800-4 .Ibsen OAC; Phelan JA (14 April 2014). Oral Pathology for the Dental Hygienist. Elsevier Health Sciences. p. 173. ISBN 978-0-323-29130-9 .Due to the side effect of deposition of tetracycline within developing teeth, it should not be prescribed to children up to 8 years of age as well as pregnant or lactating women. Clinical oral microbiology-T.Wallace Macfarlane, Lakshman P. Samaranayake. Page 217, Antibiotic/Antimicrobial Use in Dental Practice-Michael Newman/Kenneth Kornman page 80

Tetracycline has been used with some success in the treatment of localised juvenile periodontitis and this has proven to be particularly effective with in vitro studies of organisms associated with chronic and juvenile periodontitis. . Clinical oral microbiology-T.Wallace Macfarlane, Lakshman P. Samaranayake. Page 216-17

Ampicillin and amoxicillin: These antibiotics are a part of the penicillin group of antibiotics but are effective against a broader range of organisms Antibiotic/Antimicrobial Use in Dental Practice-Michael Newman/Kenneth Kornman page 72. Amoxicillin is a derivative of ampicillin. In Dentistry, Ampicillin is sometimes used when dealing with dentoalveolar infections, when the antibiotic sensitivity patterns of the causative organisms are unknown. Antibiotics are no longer used as prophylactic treatment of infective endocarditis in the UK, however, Amoxicillin was once used for prophylaxis of infective endocarditis in patients who have undergone oral surgery or deep scaling. Antibiotic and Antimicrobial Use in Dental Practice second edition-Michael G. Newman, DDS Arie J. van Winkelhoff,PhD- page 219

While effective, ampicillin is associated with a higher incidence of drug rashes than penicillin and thus, should not be prescribed to patients suffering from Infectious mononucleosis (https://en.wikipedia.org/wiki/Infectious_mononucleosis) or lymphocytic leukaemia (https://en.wikipedia.org/wiki/B-cell_chronic_lymphocytic_leukemia) as there is a higher risk of developing a drug rash. Clinical oral microbiology-T.Wallace Macfarlane, Lakshman P. Samaranayake. Page 214

Erythromycin: This is a wide spectrum antibiotic that has a similar range on the antibacterial spectrum to penicillin, making it the ideal first choice if patients are allergic to penicillin. It is also useful for treatment against B-lactamase-producing bacteria although it is not particularly as effective against oral and dental infections, due to such infections usually being caused by obligate anaerobes. Clinical oral microbiology-T.Wallace Macfarlane, Lakshman P. Samaranayake. Page 216 Antibiotic/Antimicrobial Use in Dental Practice-Michael Newman/Kenneth Kornman page 203-5

Cephalosporin: This is an example of a wide spectrum antibiotic that is relatively stable to staphylococcal penicillinase  https://en.wikipedia.org/wiki/Staphylococcus_aureus although this stability varies with different cephalosporins. Certain cephalosporins in dentistry can be administered orally while others can be given by injections. In the case of an allergy to penicillin, cephalosporins may be a suitable alternative. Clinical oral microbiology-T.Wallace Macfarlane, Lakshman P. Samaranayake. Page 215 Antibiotic/Antimicrobial Use in Dental Practice-Michael Newman/Kenneth Kornman page 155

Metronidazole: This is an antimicrobial effective against some protozoa and strict anaerobes. In the UK, it has effective use in dentistry as it is the primary drug prescribed for acute ulcerative gingivitis. (https://en.wikipedia.org/wiki/Acute_necrotizing_ulcerative_gingivitis) It is also sometimes used either alongside penicillin or alone against dentoalveolar infections with the advantage of having a low allergenicity. Mild side effects of metronidazole include transient rashes, furred tongue, an unpleasant taste in the mouth alongside several other side effects not restricted to the oral cavity. . Clinical oral microbiology-T.Wallace Macfarlane, Lakshman P. Samaranayake. Page 217 Antibiotic/Antimicrobial Use in Dental Practice-Michael Newman/Kenneth Kornman page 139, 142, 154, 164, 248, Antibiotic and Antimicrobial Use in Dental Practice second edition-Michael G. Newman, DDS Arie J. van Winkelhoff,PhD- page 120

Sulphonamides https://en.wikipedia.org/wiki/Sulfonamide(medicine)  : This a group of drugs which is used in dentistry as they have a major advantage of being able to penetrate cerebrospinal fluid and this is particularly relevant when prescribing antibiotics, prophylactically against bacterial meningitis https://en.wikipedia.org/wiki/Meningitis in patients who have had severe maxillofacial injuries, where the risk of infection is high. There are various other uses for sulphonamides as treatment with other parts of the body.

Cotrimoxazole: This is an antibiotic which incorporates sulphonamides and trimethoprim. It covers a broad spectrum of activity and in dentistry, is often used where there are clear signs and indications of bacterial infection that is sensitive to cotrimoxazole. This is determined by bacteriological sensitivity tests. Clinical oral microbiology-T.Wallace Macfarlane, Lakshman P. Samaranayake. Page 218

Clinical Applications
Glass ionomers are used frequently due to the versatile properties they contain and the relative ease with which they can be used. Prior to procedures, starter materials for glass ionomers are supplied either as a powder and liquid or as a powder mixed with water. A mixed form of these materials can be provided in an encapsulated form.

Preparation of the material should involve following manufacture instructions. A paper pad or cool dry glass slab may be used for mixing the raw materials though it is important to note that the use of the glass slab will retard the reaction and hence increase the working time. The raw materials in liquid and powder form should not be dispensed onto the chosen surface until the mixture is required in the clinical procedure the glass ionomer is being used for, as a prolonged exposure to the atmosphere could interfere with the ratio of chemicals in the liquid. At the stage of mixing, a spatula should be used to rapidly incorporate the powder into the liquid for a duration of 45-60 seconds depending on manufacture instructions and the individual products.

Once mixed together to form a paste, an acid-base reaction occurs which allows the glass ionomer complex to set over a certain period of time and this reaction involves three overlapping stages.

·        Dissolution

·        Gelation

·        Hardening

It is important to note that Glass ionomers have a long setting time and need protection from the oral environment in order to minimize interference with dissolution and prevent contamination.

The type of application for glass ionomers depends on the cement consistency as varying levels of viscosity from very high viscosity to low viscosity, can determine whether the cement is used as luting agents, orthodontic bracket adhesives, pit and fissure sealants, liners and bases, core build-ups, or intermediate restorations.

 Clinical Uses 

The different Clinical uses of Glass Ionomer compounds as restorative materials include;

·        Cermets, which are essentially metal reinforced, glass ionomer cements, used to aid in restoring tooth loss as a result of decay or cavities to the tooth surfaces near the gingival margin, or the tooth roots, though cermets can be incorporated at other sites on various teeth, depending on the function required. They maintain adhesion to enamel and dentine and have an identical setting reaction to other glass ionomers.The development of cermets is an attempt to improve the mechanical properties of glass ionomers, particularly brittleness and abrasion resistance by incorporating metals such as silver, tin, gold and titanium. The use of these materials with glass ionomers appears to increase the value of compressive strength and fatigue limit as compared to conventional glass ionomer, however there is no marked difference in the flexural strength and resistance to abrasive wear as compared to glass ionomers.

·        Dentine surface treatment, which can be performed with glass ionomer cements as the cement has adhesive characteristics which may be useful when placed in undercut cavities. The surfaces on which the glass cement ionomers are placed would be adequately prepared by removing the precipitated salivary proteins, present from saliva as this would greatly reduce the receptiveness of the glass ionomer cement and dentine surface, to bond formation. A number of different substances can be used to remove this element, such as citric acid, however the most effective substance seems to be poly(acrylic) acid, which is applied to the tooth surface for 30 seconds before it is washed off. The tooth is then dried to ensure the surface is receptive to bond formation but care is taken to ensure desiccation does not occur.

·        Matrix techniques with glass ionomers, which are used to aid in proximal cavity restorations of anterior teeth. Between the teeth that are adjacent to the cavity, the matrix is inserted, commonly before any dentine surface conditioning. Once the material is inserted in excess, the matrix is placed around the tooth root and kept in place with the help of firm digital pressure while the material sets. Once set, the matrix can be carefully removed using a sharp probe or excavator.

·        Fissure sealants, which involve the use of glass ionomers as the materials can be mixed to achieve a certain fluid consistency and viscosity that allows the cement to sink into fissures and pits located in posterior teeth and fill these spaces which pose as a site for caries risk, thereby reducing the risk of caries manifesting.

·        Orthodontic brackets, which can involve the use of glass ionomer cements as an adhesive cement that forms strong chemical bonds between the enamel and the many metals which are used in orthodontic brackets such as stainless steel.