CAD/CAM international magazine of digital dentistry

28 I I special _ occlusion _The physiological influence of interfering initial contacts For most of the patients, their habitual position of the mandible in maximum occlusion is the pre- ferred position for occlusal restoration. However, even a tiny interfering prematurity contact of only 20 µ can trigger a compensatory reaction, placing themandibleintoanewphysiologicalposition.This isanaturalreactionofourbiologicalsystemtoavoid higher forces focused only on one area. Forexample,ifyouareeatingsomethingandyou chew on a little grain of sand, you automatically shiftyourmandibletoadifferentpositiontoprotect yourteeth.Apermanent“grainofsand”(occlusalin- terference) can trigger an overload of the biological system, in which case the patient will have reached his or her maximum capacity for compensation. Pain symptoms can then become chronic. _Occlusal restoration In order to reconstruct physiological occlusion, correct visual identification of contact points is es- sential. Occlusion checking materials (articulating papers) with the effect of progressive colour trans- ferarehelpfulinidentifyingocclusalforcesininter- cuspal habitual position. Areas with higher force loads can be identified as darker-shaded markings with higher contrast. These markings likely indicate the initial contacts. Areas with less intense colour markings indicate contacts with lower occlusal forces or areas with no contact. Upon close exami- nation, these markings look like a donut. The centre of the contact point has a lighter shade. The more intense-coloured edge of the contact point is not partofthecontact.Justthe lighter-coloured centre is the real contact area. For occlusalequilibration,only these areas should be ad- justed. For a balanced oc- clusion, the patient should haveenoughABCcontacts on each quadrant. Occlusalcorrectionscan be additive or subtractive. If modification of the occlusal relationship in patients who have been grinding their teeth over a long period is needed, this may be challenging, as they would already have lost a significant part of their hard tooth tissue. A splint is indicated for treating such patients (additive occlusion). _Conclusion The reconstruction of physiological occlusion is essential for the complex functioning of the entire stomatognathic system. There are various concepts of occlusion. For recording and analysing the com- plex movement of the mandible, a wide range of electronic devices are available. Beside all these tools, a basic understanding of the biomechanical design of an occlusal surface is essential. Today, we have a wide selection of dif- ferent occlusion indicators to visualise these bio- mechanical structures. Soft colour-impregnated occlusioncheckingpapers,incombinationwiththin occlusion checking films, are optimised for visual checking of the occlusal relationship between the maxilla and mandible._ CAD/CAM 4_2012 Dr Peter Bausch Dr.Jean Bausch GmbH & Co.KG Oskar-Schindler-Str.4 50769 Cologne Germany pb@bauschdental.de CAD/CAM_contact Fig. 14Fig. 13 Fig. 12Fig. 11