Fixed Prosthodontics Armamentarium and Reduction Matrices PDF

Fixed Prosthodontics (Armamentarium and Reduction matrices) Bur types o Diamond vs carbide o Shape, size, taper, grit, specialty o Uses and applications Reduction Matrixes o Lab putty properties o Mixing, Placement, Sectioning and usage Carbide burs vs. Diamond burs...

Fixed Prosthodontics (Armamentarium and Reduction matrices) Bur types o Diamond vs carbide o Shape, size, taper, grit, specialty o Uses and applications Reduction Matrixes o Lab putty properties o Mixing, Placement, Sectioning and usage Carbide burs vs. Diamond burs Tungsten carbide burs: aka carbide burs are made of tungsten carbide and have a set number of blades o Blades aid in cutting and reduce chatter (not good for crown preps) o These blades slice away pieces of tooth structure and lead to a cleaner finish of cut. o Have various shapes, head angles, blade geometry, etc. o Defined by number system (i.e. 330, 557). Diamond Burs o Constructed of stainless steel body bonded with diamond particles o Come in different shapes, grits, widths, and lengths o Identified by numerical code which can be found on bur packaging. o Grind away hard tissue rather than cut. § Creates more friction and wear and tear on the burs § Overuse of diamond burs leads to decreased cutting efficiency and overheating of bur and tooth Shape o Indicated by the THREE numbers before the period in the number code. o Various shapes and tapers, 856 refers to round end taper Grit (these are not for polishing, these can be used for finishing)  Cutting Diameter o Cutting diameter is indicated by the LAST numbers on the item code o These last numbers refer to maximum cutting diameter of the bur at its widest point in mm. o Ex. 016 refers to a bur 1.6mm wide at the widest point. Cutting Length o Denoted by a two-digit number between the periods in the item code. o 31 refers to the standard bur length, which is 19mm. Why have so many burs? o Bur design should be matched to its application. o Ex: When creating a shoulder margin → shoulder bur (flat end taper) will most easily create this margin. o Other burs have special uses § Barrel burs for reducing occlusal surfaces on molars § Wheel burs for incisal edges § Egg reduces lingual on anteriors Reduction Matrices o When cutting preps, we measure prep depth relative to unprepped tooth (ie. cavosurface margin) o This reduces the tooth from all dimensions and needs a way to measure how much we have reduced o Lab putty is made of ADDITION SILICONE § Excellent dimensional stability § Good accuracy § Fairly stiff when set o Impression is taken of the tooth to be prepped o This impression is the reduction guide o Sectioned at each cusp to be prepared in order to evaluate reduction height at each of these cusps. § Anteriors and premolars are sectioned in 2 § Molars are sectioned in 3