cosmetic dentistry - beauty & science

special topic _ minimally invasive cosmetic dentistry I and measure them clinically. Therefore, the force is the most neglected component in cosmetic dentistry during case finishing. When the force components are not ad- dressed properly during the treatment, clinicians mayencountervariousclinicalproblems,suchas damaged restorations (veneers, onlays, crowns and bridges); fractured teeth; tooth mobility; abnormal tooth wear and sensitivity; pain in the teeth, muscles and jaw joints; and increased neck pain, ear pain and headache. In cosmetic dentistry, forces are finished based on articulating paper mark interpretation and the patient’s proprioception feedback. It has been documented in the literature that ar- ticulating paper is a poor indicator of occlusal disharmony and cannot measure occlusal load and the timing of tooth contacts. The proper tools and techniques can measure precisely and objectively the necessary occlusal parameters required for finishing the force components in cosmetic dentistry. Minimally invasive cosmetic dentistry cus- tomised case finishing integrates the concept of force finishing into the conventional case- finishing protocol of dentistry, in the hope that it will help practitioners to achieve long-term optimumresultsintermsofhealth,functionand aesthetics, and high patient satisfaction with minimal biological cost. _Introduction The treatment modalities and protocol of health care should be aimed at the establisment ofhealthandthepreservationofthehumanbody withitsnaturalfunctionandaesthetics.Thecom- prehensive concept of minimally invasive cos- meticdentistry(MiCD)anditstreatmentprotocol were introduced in 2009 with the basic aim of a clinician effecting optimum clinical therapeutic improvements in smile enhancement, while per- forming corrective procedures that require as little clinical intervention as possible.1 The intervention level of the treatment in MiCD depends on the type of smile defects and the aesthetic needs of the patient.1 The five core principles (Fig. 1) of the MiCD concept help to guide the clinician in achieving the desired smile enhancement with minimal clinical inter- vention. However, the core principles must be adapted from case selection to the final case- finishing stages. Proper case finishing is not possible without understanding its two com- ponents, namely the micro-aesthetics and the occlusal forces. It is, however, the force component that is often neglected, or improperly considered, in cosmetic dentistry. This article describes an MiCD customised case-finishing (MCCF) concept and protocol that respect both force and aesthetic components. _MiCD customised case-finishing concept Case finishing is one of the most important steps in any clinical treatment in dentistry. It has three major components that need to be con- sidered: aesthetics, overall health and occlusal function. It is interesting to note that case finishing is viewed differently in different dis- ciplines of dental medicine. In orthodontics, Fig. 4_Jaw-position theories. Fig. 5_Mechanism of occlusion-force alteration.15 I 07cosmeticdentistry 3_2012 1.Centric relation theory (Schuyler):8 The occlusion is determined by the manner in which the ligaments brace the components of the jaw joint,particularly the rearmost hinge axis.There are various clinical techniques proposed to record centric relation (CR).The bimanual manipulation technique of Dawson,9 the Lucia jig and the leaf-gauge technique, as reported by Long,10 are popular techniques for positioning the mandible in CR. Prior to this, chin-point guidance and swallowing techniques were used to locate and record CR. 2.Neuromuscular theory (Jankelson):11 The occlusion is determined by gravity and based on the position in which the jaw muscles are most relaxed.Trans Electric Nerve Stimulation (TENS) is employed to relax the muscles. 3.Intercuspal theory:The occlusion is determined by the habitual fit with the most tooth contact. 4.Anterior protrusive position theory (Gelb 4/7 position):12 The occlusion is determined by the manner in which the muscles brace the components of the jaw joint. The Gelb 4/7 jaw positionisfoundbyusingappliancestoopentheocclusionandrepositionthemandibleforwards and downwards of the true centre of the glenoid fossa. Fig. 4 Clinicianscanaffecttheocclusalforcesbyalteringthefollowingfiveareasduringocclusalscheme preparation:15 1.Intercuspal position (ICP) contacts: Restorative dentists can control which teeth come into contact and the number of tooth contacts during closure in the ICP. 2.Excursivecontacts:Byalteringthenumberandtypeoftoothcontactsineccentricexcursions, restorativedentistshavetheabilitytochangemuscularcontractionandthedistributionofforces. 3.Angleoftoothcontacts:Itiswellknownthatthedepthoftheoverbiteorsteepnessoftheangle of guidance of the teeth will have an impact on the manner in which forces are distributed.37, 38 Theangleofimpactwillaffectnotonlythedistributionoftheforcebutalsotheabilityofthemuscle to contract. 4.Condylar position: The condylar position chosen will have a dramatic impact on the ability to control which teeth contact each other and when they contact. 5.Verticaldimensionofocclusion:Theverticaldimensionofocclusioncanbeopenedorclosed when restoring at least one arch.Decreased vertical dimension increases the occlusal forces. Fig. 5