Dental polishers
Dental Polishers
In dentistry and dental technology very different materials require smoothing and polishing. This ranges from exceptionally hard natural tooth enamel to the surfaces of filling materials (composites, compomers or amalgam), fixed restorations (metal alloys or ceramics), implant components (titanium, other metals or zirconia), appliances, splints or dentures (all types of hard and soft materials).
The dental polishers used in standard handpieces are rotary instruments with a metal or plastic shank. The smoothing and polishing section of the instrument is attached to the shank – whether rigidly connected or via press-on, clamp or screw connection (e.g. with mandrels). Some polishers are not active themselves and require the additional use of polishing pastes as consumable materials (in particular for prophylaxis).
Easy, clean results are produced with all other polishers. In this case the working section is made of rubber or silicone. Abrasive materials (e.g., silicon carbide or corundum and mainly diamonds are used for very hard materials, in particular ceramics) of a suitable, selected grit size are embedded in the surface or impregnate the entire working section.
A wide range of polisher shapes is available for different applications. Typical shapes are points, cups and discs for the dental practice and wheels, cylinders/arbor bands and torpedoes for the dental laboratory.
A dental polisher
Surfaces of materials are smoothed and polished in one or more working stages. Technically, the individual processing stages vary either in the different pressure applied and/or motor speed but mainly by using abrasives/polishers with different degrees of hardness and grit sizes (specific for each stage). Polishing techniques often differentiate between two-step pre-polishing (coarse polish) and high-lustre polishing (fine polish), depending on the material, initial condition, required final state and up to three steps. The first/coarsest step is frequently a transition from preparing/contouring; at this stage significant (macroscopic) amounts of material are still removed. In the subsequent steps the main focus of the work is more on reducing (increasingly microscopic) surface irregularities (surface roughness). The final step produces a smooth surface, in general with a silky sheen or high-lustre/shining finish. Often the different colours of the polishers facilitate the assignment of specific instruments to the respective working stages. All diamond grit polishers have uniformly standardised coloured rings for identifying the different fineness of each polishing step.
To rule out cross contamination between patients in clinical dental medical applications, preference should be given to polishers, which are either suitable for sterilisation in an autoclave to ensure safe multiple use or which are designed as single-use products from the outset (use for one single patient only).
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Focus text of the month
Sleep apnoea Sleep apnoea Compared with healthy sleep, there is a great increase in breathing cessations (AHI = apnoea/hypopnoea index > 10 per hour), in the form of complete apnoea or reductions in airflow (hypopnoea). Central nervous system causes are rarer than the much more common OSA (obstructive sleep apnoea) of local (peripheral) origin. This itself causes central cessations, so mixed forms often occur (approx. 90%). OSAS (obstructive sleep apnoea syndrome) is nearly always associated with heavy snoring that disturbs other sleepers. The interaction of a number of factors, such as supine sleeping position, slack pharyngeal musculature, especially involving the soft palate and uvula and also the hypopharynx (e.g. due to alcohol consumption, sleeping pills), physiological and pathological anatomy (obstructed nasal breathing, enlarged tonsils, macroglossia, obesity) causes temporary complete obstruction of the airways during inspiration. This causes a drop of about 4% in the blood's oxygen saturation, which is normally 95% to 100% so the oxygen supply to the tissues is impaired. If the episode lasts longer, hypercapnia (a rise in carbon dioxide level) may occur. This then triggers frequent "micro-arousals" via chemosensors, which often do not lead to full awakening; sleep is disturbed with shortened deep sleep phases and an overall reduction in sleep quality with lower relaxation and recovery, which can lead to an increased need for sleep and increased daytime tiredness, daytime somnolence (hypersomnia) and a tendency to fall asleep. In the long term, apart from quality of life and energy levels, life expectancy is also affected as OSA is associated with high blood pressure, cardiac arrhythmias and depression and there is an increased tendency to stroke, heart attack and accidents. The diagnosis can be confirmed by recording relevant parameters during sleep at home (cardiorespiratory polygraphy) or in hospital (polysomnography when the patient spends the night in the sleep laboratory); these include ECG, pulse oximetry, EEG, video recording, etc.
Various approaches are used in treatment, alone or in combination:
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Polysomnogramme with hypnogramme