Preclinical 2 Tools: Trays, Base, Setting 3 (PDF)

Impression trays  Instruments Rubber bowl Rubber bowl is used for the manipulation of plaster, stone and alginate. It is available in different sizes. It is made of stiff and flexible rubber Straight mixing spatula Straight mixing spatula is used for mixing dental plaster and de...

Impression trays  Instruments Rubber bowl Rubber bowl is used for the manipulation of plaster, stone and alginate. It is available in different sizes. It is made of stiff and flexible rubber Straight mixing spatula Straight mixing spatula is used for mixing dental plaster and dental stone. The blade of the metallic spatula is straight with a rounded end. The handle is made of plastic Curved mixing spatula Curved mixing spatula is used for mixing alginate. The blade of the metallic spatula is curved with a rounded end. The curved end helps in the mixing of the alginate material. Plaster knife The plaster knife is used in trimming of plaster models. The blade of the plaster knife is metallic and is sharp. The handle is made of plastic. It can also be used during the manipulation of other gypsum products Wax knife Wax knife is used commonly during fabrication of wax occlusion rims, teeth arrangement, wax up procedures and for finer manipulation of dental plaster during procedures, like mounting and flasking. It has a knife-like end on one side for cutting wax and the other end has a scoop used for carrying the molten wax and manipulating curved wax surfaces Wax carver Wax carver is an instrument used for carving the wax patterns of the tooth. The carver has two ends, one end is a scoop used for scooping out wax and the other end has a sharp blade end for carving the pattern in wax. Frequent heating of the wax carver may cause bluntness of the carving tip. Wax carver is also used in finer manipulation of gypsum products. Spirit lamp Spirit lamp has metallic container with a provision for placing the wick and a metallic cap to close the wick. Spirit is poured into the container and a cotton wick is inserted into it. It gives a continuous noncarbon flame. It is used during the chairside clinical procedures for heating of instruments, like wax carver and wax knife Gas torch Gas torch is a self-igniting handheld flame torch. Gas torch gives a continuous noncarbon flame. The gas torch is filled with butane gas,which is commercially available. It is used during fabrication of shellac record bases, fabrication of wax occlusion rims and for chairside heating of instruments, like wax carver and wax knife. Hot plate Hot plate is used for uniform reduction of occlusion rims. It has a broad metal plate with a plastic handle Dental flask Dental flask is used for investing the waxed denture in dental plaster for processing into acrylic denture The dental flask consists of three components namely the base, the body and the lid. There are orienting prongs in the base and corresponding notches in the base, which will help in assembling the base and the body. Glass slab and mixing spatula Glass slab and mixing spatula are used for mixing zinc oxide eugenol impression material and light body elastomeric impression material. The blade of the mixing spatula is about 5 cm in length and flexible. Acrylic trimmer tungsten carbide Acrylic trimmer is a motor-driven tool used for trimming the acrylic resin. It is available in various forms and sizes. It is used during the gross trimming of the acrylic dentures after processing of the dentures  Dental casts Dental cast A positive life-size reproduction of the oral cavity Requirements of the cast 1. Include all anatomic surfaces of the final impression. 2. Show a full peripheral border with a depth of 2–3 mm. 3. Include a 2–3 mm of land area around the entire periphery of themaster cast 4. The land area should be slightly tapered outward. 5. The base of a cast should not be less than 10– 12 mm at the thinnest point. 6. The cast contains no bubbles or flaws Study or diagnostic cast A life-size reproduction of a part or parts of the oral cavity and/or facial structures for the purpose of study and treatment planning. It is made from a preliminary impression. The casts are usually made of dental plaster and dental stone. Master cast or final cast or working cast A positive replace of the tooth surface and other parts of the dental arch or facial structures which is used for the fabrication of dental restorations or prosthesis. Master casts are made in dental stone and die stone. Dental stone and die stone have better strength compared to dental plaster. Impression trays Definition A receptacle or a device that is used to carry, control and confine the impression material while making an impression. Requirements of impression tray 1. The impression tray should be rigid. 2. It should be dimensionally stable. 3. It should provide space for impression material while making an impression. 4. The borders of the tray should be smooth so that it does not injure the oral tissues 5. The method of construction of the custom trays should be simple. 6. The borders of the tray should be easy to trim. Types of impression trays Impression trays can be classified as: Based on purpose or use Based on material Based on purpose or use Based on material Stock trays or prefabricated trays 1. Stock trays are rigid. 2. They are dimensionally stable. 3. The trays can be used several times. 4. They are available in different sizes and specifically for upper and lower arches 5. The perforations in the trays help in retention of the set impression material while removing the impression from the patient’s mouth. 6. Tray adhesives have to be applied for elastomeric impression material. 7. The flanges of the stock tray cannot be contoured. 8. The space for the impression material is not uniform Edentulous stainless steel stock tray Edentulous stainless steel stock tray is used for making impressions of edentulous patients with impression compound. It is a prefabricated nonperforated impression tray made of stainless steel. The impression tray has a carrier for carrying the impression material and a handle for positioning and handling the impression The lower tray is U-shaped to accommodate the tongue whereas the upper tray is shaped to accommodate the palate and alveolar ridge Dentulous metallic stainless steel stock tray Dentulous metallic stainless steel stock tray is used for making impressions of dentulous patients It is a prefabricated impression tray made of stainless steel with perforations, which aids in the retention of impression material, such as alginate. Custom trays Custom/individualized trays can be fabricated and used for the individual patients. Custom trays can be made for both dentulous and edentulous arches. The custom trays are fabricated on the preliminary casts. Custom trays can be made with self-cure resin and shellac baseplate. Custom trays provide uniform space for the impression material. The flanges of the tray can be modified according to the sulcular extension. The dimensional stability and the rigidity are less compared to the stock trays. The fabrication process is time-consuming.  Impressions in complete denture Definition of impression Objectives of impression making Types of impressions Theories of impression making Materials used for impression making Definition of impression A complete denture impression is a negative registration of the entire denture bearing, stabilizing and border seal areas present in the edentulous mouth. Objectives of impression making The objectives of impression making in complete dentures: i. Preservation of residual alveolar ridge ii. Retention iii. Stability iv. Support v. Aesthetics  Types of impression 1.Based on the purpose.1 Preliminary/diagnostic impression A negative likeness made for the purpose of diagnosis, treatment planning or the fabrication of a tray. An impression of the edentulous arch used to make a cast for the fabrication of the custom tray or individualized tray. Alginate impression material or impression compound is used in a stock impression tray for making preliminary impressions. Making of the primary cast with a base from primary edentulous impressions pouring the primary impression with dental plaster and making the base for the cast with dental plaster simultaneously. The steps involved are as follows: 1. Marking the outline 2 mm below the sulcus. 2. Pouring the primary impression with dental plaster. 3. Making of a base for the primary cast. Marking the Outline 2 mm below the sulcus of the impression The primary impression is taken and the outline of the sulcus is marked 2 mm below the sulcus with marker pen along the anterior and posterior borders of the sulcus Pouring the primary impression with dental plaster The dental plaster is mixed in the rubber bowl with proper water–powder ratio and is poured in the primary impression without any voids. Making the base for the cast from the primary impression. Dental plaster is mixed in a rubber bowl and is poured on the glass plate The poured impression is inverted and placed on the mixed dental plaster on the glass plate. Base plaster is placed up to the marked outline of the primary impression Once the base plaster is set, it is removed from the glass plate. The poured cast with base in the primary impression is kept in hot water bath, The impression compound softens and the primary cast is separated from the primary compound impression Excess material of the base plaster is removed, and the height of the cast should be 12–15 mm  Types of impression Master/final impression: A negative likeness made for the purpose of fabricating a prosthesis. An impression that represents the completion of the registration of the surface or object. Elastomeric impression material or zinc oxide eugenol impression material is used for making final impressions using a custom tray or individualized tray  Types of impression 2. Based on theories of impression making The impression techniques are based on the amount of pressure applied during making of impressions Mucocompressive theory The tissues of the oral cavity are recorded in the functional position. The impression of the tissues is recorded when pressure is applied on the stress bearing and nonstress-bearing areas causing maximum tissue displaceability. In this impression technique, impression material with high viscosity like impression compound and putty consistency of elastomeric impression material can be used Mucostatic impression theory In mucostatic impression technique, the tissues are recorded in rest position. The pressure applied in this technique is very minimal. There is no displaceability of tissue. In this impression technique, impression material with low viscosity, like light body consistency of elastomeric impression material, impression plaster and alginate can be used. Selective pressure theory Selective pressure technique employs both mucostatic and mucocompressive techniques. The pressure is applied on the stress-bearing areas and less pressure is applied on the nonstress-bearing areas. This is achieved using custom impression trays with spacer designs. Impression materials like zinc oxide eugenol impression paste and light body consistency of elastomeric impression material are used. The spacer designs are done by adapting wax on the preliminary cast before making the custom tray. The spacer designs are based on the areas of relief where only minimal pressure is applied. Tissue stops are given in the full spacer design. Four tissue stops are given, two in the canine region and two in the molar region in the maxillary arch spacer design and in the mandibular arch, two tissue stops are placed in the anterior canine region and the buccal shelf area is relieved in the spacer design which acts as a tissue stop. The wax is cut in a square dimension of 4 mm × 4 mm. Tissue stops help in reseating of the tray while making the final impression and prevent in the apical displacement of the impression while making an impression.  Complete denture fabrication Armamentarium Dental casts Metallic scale Pencil or marker pen BP handle with blade no. 15  Border moulding and secondary impression The borders of the custom tray are shaped or contoured to the sulcular extension of edentulous maxillary and mandibular arches with the help of tracing compound or heavy body elastomeric impression material to obtain a peripheral seal in the custom tray. Master or final impression is then made with zinc oxide eugenol impression paste or light body elastomeric impression material  Custom impression tray fabrication forupper and lower edentulous Step I: arches Outline of sulcus, custom tray border, wax spacer and tissue stops. Step II: Adaptation of wax spacer. Step III: Fabrication of resin custom tray. The technique of fabrication of resin custom tray can be done by two methods. 1. Finger adapted method. 2. Sprinkle on method. Step I: Outline of sulcus, custom tray border, wax spacer, tissue stops The outline of the sulcus is marked in the preliminary cast with a black coloured pencil in the upper and lower edentulous casts The periodontal probe is placed in the sulcus and the 2 mm marking is done The 2 mm markings are done on the cast with the probe along the labial and buccal sulcus on the cast Outline of the wax spacer The outline of the wax spacer is drawn with a red- coloured pencil.The spacer outline is done at a level of 2 mm short of the tray outline. The spacer outline in the posterior aspect of the maxillary cast is limited to the anterior vibrating line of the posterior palatal seal area. In the mandibular cast, the buccal shelf area is not included in the spacer design. The buccal shelf area is limited anteriorly by the buccal fraenum, posteriorly by the anterior aspect of the retromolar pad, medially by the crest of the alveolar ridge and laterally by the buccal sulcus. Outline of tissue stops Four tissue stops are outlined in the maxillary cast, two in the anterior canine region and two in the posterior molar region A 4 × 4 mm square is outlined with a red- coloured pencil in the above-mentioned region. In the mandibular cast, two tissue stops are outlined in the anterior canine region only. Step II: Adaptation of wax spacer A half sheet of modelling wax is softened over a Bunsen burner and is adapted on the cast without any wrinkles The wax spacer is trimmed on the cast to the derived outline with a no. 15 BP blade The tissue stop area is also cut along the outline drawn of 4 × 4 square dimensions. The outline of wax spacer is done at a level of 4 mm short of the sulcus and in the posterior aspect is limited to the anterior vibrating line Finger adapted method The finger adapted method is the most widely used technique of making impression trays. The resin is mixed in the form of dough and is rolled to the desired thickness with the help of a template and is adapted to the cast with finger pressure. In this technique, as we use the template, there is a control over the uniform thickness of 2 mm of resin impression tray. The resin dough is adapted with light finger pressure starting from the mid palatal area to the crest of the ridge and ending over the sulcus The adaptation should be continuous. If not done continuously, there may be rebound of tray material resulting in poor adaptation of the tray material to the tissue surface of the cast, especially in the posterior palatal seal area The tray material is adapted on the lingual side, then over the crest of the ridge and along the buccal slope of the ridge ,The excess material is cut with a no. 15 BP blade along the anterior and posterior desired outline, The adaptation of the resin material should be continuous because there may be a rebound of the material causing a space to cover between the tissue surface of cast and the tray There should be close adaptation of the tray especially in the posterior palatal seal area and in the lingual aspect of the mandibular tray. The polymer and monomer are mixed in a porcelain cup. When it reaches the dough stage, it is removed and adapted on the anterior portion of the upper tray to make a handle The handle should be approximately 3–4 mm thick, 8 mm in length and 8mm in height. The handle of the tray should be inclined at an angle of 45 degrees. The handle should be positioned in such a way that it should not interfere with the lip movements of the patients during border moulding and impression making. The handle for the lower tray should be straight. Stabilizing handles one on either side are positioned posteriorly. The borders of the tray should be smoothened with tungsten carbide bur followed by using sandpaper The borders of the tray should be smooth and uniform. The relief for the labial and buccal frenum is adequately given in the custom tray Beading and boxing of maxillary and mandibular edentulous impressions Maxillary and mandibular edentulous impressions have to be poured into the making of final or master cast for the fabrication of the complete removable prosthesis. The master cast has an art portion and the anatomic portion The art portion of the cast is the land area which is 2 mm in width and is 2 mm above the vestibular sulcus. The maxillary cast has a height of 10 mm from the deepest part of the sulcus. The mandibular cast has a height of 15 mm from the deepest part of the sulcus, i.e. the posterior lingual sulcus In order to create the land area and the height of the master cast, beading and boxing of the impressions are done with wax and finally the boxed impressions are poured with dental stone The procedure for the beading and boxing of maxillary impressions involves the following steps: Beading of maxillary impression Boxing of maxillary impression Pouring the impression with dental stone The procedure for the beading and boxing of mandibular impressions involves the following steps: Beading of mandibular impression Creation of tongue space Boxing of mandibular impression Pouring the impression with dental stone ARMAMENTARIUM: 1. Beading wax 2. Boxing wax 3. Maxillary and mandibular edentulous impressions 4. Wax knife, wax carver, wax spatula 5. Modelling wax sheet 6. Bunsen burner 7. Metallic scale Beading of maxillary impression The beading wax should be 3 mm width and is placed at 2 mm below the sulcus. The beading wax is placed from the distobuccal area to the labial frenum relief area. The beading wax is placed and sealed with molten wax along the entire vestibular sulcus. This creates the land area of the master cast. The beading wax is placed and sealed with molten wax from the labial frenum relief area to the other distobuccal area Boxing of maxillary impression Boxing wax is measured and cut according to the height of the sulcus measured from the deepest part of the sulcus, which should be 10–12 mm.Boxing wax strip is taken and placed along the entire beading wax in the anterior region. The boxing is placed at the posterior area of the impression and is sealed with the molten wax. The boxing creates the height and base of the cast. The boxing wax at the posterior end is sealed completely with molten wax. The height of the boxing wax should be 10–15 mm from the deepest part of the sulcus. Pouring of maxillary impression Dental stone is mixed in appropriate proportion in a rubber bowl and is poured into the beaded and boxed maxillary impression without any air bubbles. The material is allowed to set for 30 minutes, and the final cast is removed from the impression. The final cast is checked for the land area and the height of the cast Beading of mandibular impression The beading wax should be 3 mm in width and is placed at 2 mm below the sulcus. The beading wax is placed from the distobuccal area to the labial frenum relief area. The beading wax is placed and sealed with molten wax along the entire vestibular sulcus. This creates the land area of the master cast. The beading wax is placed and sealed with molten wax from the labial frenum relief area to the other distobuccal area Creating tongue space A sheet of modelling wax is placed below the impression. The outline of the lingual borders of the mandibular impression is marked on the wax sheet. The outlined area is cut out from the wax sheet. The cut out tongue space wax is softened and is placed and sealed with molten wax at 2 mm below the sulcus. This is done to create the tongue space in the mandibular master cast. The height of the boxing wax sheet is measured from the deepest part of the msulcus (should be 12–16 mm). Boxing of mandibular impression Boxing wax strip is taken and is placed along the entire beading wax. The height of the boxing wax should be 10–15 mm from the deepest part of the sulcus from the distolingual area. The boxing is placed along the posterior lingual area of the impression and is sealed with a molten wax. The boxing creates the height and base of the cast.. Pouring of mandibular impression Dental stone is mixed in appropriate proportion in a rubber bowl and is poured into the beaded and boxed maxillary impression without any air bubbles. The material is allowed to set for 30 minutes, and the final cast is removed from the impression. The final cast is checked for the land area andthe height of the cast. Record bases Definition Record base is an interim denture base used to support the record rim material for recording maxillomandibular relations. Requirements 1. The record bases should be rigid. 2. The record bases should be dimensionally stable. 3. The borders of the record bases should be the same as the finished denture. 4. The record base should be closely adapted to the tissue surfaces of the cast. 5. The record base constructed should permit its use as a base for setting the teeth. 6. It should be easy to construct and the material should be inexpensive Types of record base Shellac record base in an edentulous cast  Shellac record base Advantages Record bases can be easily fabricated – it is not time- consuming. They are closely adapted to surface the master cast. They are inexpensive and easily available. Record bases with shellac baseplate can be easily corrected. Uniform thickness can be maintained. Disadvantages Shellac baseplates have less strength. Shellac baseplates easily break. During setting of teeth or fabrication of rims, they tend to distort/wrap due to repeated changes in temperature.  Self-cure resin Advantages They have better strength. They are dimensionally stable. They have better stability and do not wrap due to repeated changes in temperature. They are closely adapted to the tissue surface of the cast. They can be easily trimmed with the acrylic burs. Disadvantages Fabrication process is time-consuming. During fabrication, it is difficult to control the thickness. Residual monomer present in record bases can cause irritation to oral tissues Self-cure resin record base on an edentulous cast  Light-cure resin Advantages They are easy to fabricate. They have better stability. They are closely adapted to a tissue surface of the cast. They can be easily trimmed with acrylic burs. Residual monomer content is less when compared to self-cure resin. Disadvantages Fabrication process requires a special equipment for curing of the material. They have less strength when compared to heat-cure and self- cure resin. It is difficult to maintain a uniform thickness of the record base. The denture base tends to wrap after prolonged use. Light-cure record base  Permanent record base Heat-cure acrylic resin Advantages They are rigid, accurate and dimensionally stable record bases. The record bases will become part of the completed prosthesis. The processing errors will be minimized. They require only minimal finishing and polishing. Disadvantages It is a time-consuming process and needs to prepare a mounting cast for articulation. Heat-cure resin record base on an edentulous cast  Metal denture bases Advantages They form rigid, accurate, dimensionally stable record bases. They become part of the final denture. They are good conductors of heat and help in improving sensitivity to heat and cold. They are formally advised for patients with frequent breakage and high gag reflex patients. Disadvantages The fabrication process is time-consuming. Cr-Co alloy metal denture base on the cast. Upper complete denture with metal denture base  Fabrication of occlusion rims Guidelines are marked on the maxillary cast for fabrication of the occlusion rim 1. Mark the maxillary tuberosity of the cast 2. Mark the anterior border of the tuberosity on the land area of the cast. 3. Mark the incisive papilla. 4. Mark the midline of the cast by connecting mid palatine raphe, incisive papilla and the labial frenum. Extend this line to the land area of the cast. 5. Draw a perpendicular line to the midline through the center of the incisive papillae and extend it to the land area and this line is called canine–papilla–canine (CPC) line The midline, CPC line and limiting of the posterior extent of maxillary occlusion rim are visible on the land area following placement of adapted shellac baseplate 1. The posterior extent of the mandibular guideline for occlusion rim is marked on the land area 2. The guideline for the height of posterior occlusion rim is marked on the land area. 3. Two markings are done: one in the anterior and another one in the posterior aspect on the land area of the cast for depicting the crest of the ridge. Three guidelines on the mandibular edentulous cast are marked. These are: 1. The retromolar pad area is marked and is divided into three parts: anterior one-third, middle one-third and posterior one-third. The height of mandibular posterior occlusion rim should be at the level of the junction of anterior two-thirds and posterior one-third. 2. The posterior extent of the mandibular rim should be limited to the anterior aspect of the retromolar pad. 3. The crest of the alveolar ridge is marked and is extended posteriorly and anteriorly, which serves as a guideline for fabrication of the occlusion rim. The width of the posterior occlusion rim should be equidistant or equal on either side of the crest of the ridge. Fabrication of maxillary occlusal rim  Occlusion rim Definition Occluding surfaces fabricated on the interim or final denture bases for the purpose of making maxilla mandibular relationship records and arranging teeth. Uses of occlusion rim Occlusion rims are used to establish the level of occlusal plane. Occlusion rims are used to establish maxilla mandibular records like vertical and horizontal jaw relations. The midline, canine line, high lip line and low lip line, and inter canine distance are recorded on the wax occlusion rims. Occlusion rims help to determine the length and width of the artificial teeth. Midline of the arch for the correct placement of the central incisors. Occlusion rims help to obtain proper lip support. Dimension of occlusion rims The occlusion rim should follow the arch form of the residual alveolar ridge and should be placed on the ridge where the natural teeth were originally present. The position of the occlusion rim on the edentulous alveolar ridge is as follows: Height of occlusion rim in the anterior region Height of the occlusion rim in the posterior region Width of the upper occlusion rim.  Lower posterior rim in relation to crest of the ridge  Articulators Uses of an articulator 1. To simulate the patient’s TMJ movements and mandibular movements. 2. Mounting the dental casts in a fixed relationship. 3. Mounting the dental casts for proper diagnosis, treatment planning andpresentation to the patient. 4. To help in the fabrication of fixed and removable restorations. 5. To arrange artificial teeth. 6. To correct and modify the existing restorations Advantages of an articulator It is helpful in visualizing the patient’s occlusion with much more ease, especially the lingual occlusion. Patient cooperation is not needed while using the articulators because the articulator itself provides the necessary movements. It is more comfortable and there is refinement in the work, as there is no disturbance, like shifting of denture base or resiliency of the soft tissues. Reduced chair time with the patient. Role of patient’s saliva, tongue, cheeks and posture is avoided Mean value articulator Parts of the mean value articulator Mean value articulator: Mean value articulator has a fixed condylar guidance of 33 degrees and incisal guide table 1. Upper member 2. Lower member 3. Incisal guide table 4. Vertical incisal rod 5. Central pin 6. Condylar guide 7. Stabilizing rod Upper member: The upper member is a triangular frame with base of the triangle placed posteriorly and two condylar elements seen projecting on either side of the base The apex of the triangle is seen anteriorly and it has a provision to hold the incisal rod with a central pin. The vertical incisal rod can be locked with the help of a thumb screw. The maxillary cast is mounted to the upper member during articulation. Lower member: The lower member of the articulator consists of two components, the horizontal frame and the vertical frame. The horizontal frame is triangular in shape and corresponds to the lower member. In the centre, the lower mounting plate attached. The anterior aspect of the horizontal frame houses the incisal guide table. The upper part of vertical frame houses the condylar guide. Mounting plates: They are two in number, one for the upper member and other for the lower member The mounting plates are attached with the help of thumb screw to the articulator. The upper and lower casts are attached to the articulator with the help of mounting plates. Incisal guide table: Incisal guide table determines the incisal guidance of the articulator The upper surface of the incisal guide table is concave, and the vertical incisal rod should be in centre during the articulation. The depth of the concavity is designed to have a slope equal to the average of 15-degree incisalguide angle. Vertical incisal rod: Vertical incisal rod helps to maintain a fixed distance between the upper and lower members It has a pointed tip which should rest in the centre of the incisal table during articulation. The positioning of the incisal pin can be adjusted with the thumb screw attached to the upper member. Central pin: At the midpoint of the incisal rod, there is a hole provided to fix the central pin The tip of the central pin corresponds to the anterior plane of occlusion during articulation. During teeth setting, the incisal edge of the maxillary incisors should be in contact with the central pin. Condylar guide: Condylar guide guides the movement of the condyle. In a mean value articulator, the condyle guidance is in two parts, which are condylar track and the condylar element.The condylar track is located in the lower member, inclined at an angle which is average inclination of condylar guidance (33 degrees) of the population. The condylar element is seen projecting out from the base of the triangle of the upper member. A spring isplaced within the track to hold the condylar element in its most posterior position Stabilizing rod: Some mean value articulators have the provision of attaching the stabilizing rod. It helps the dentist during his work. It helps to stabilize the upper member of the articulator, while it is kept open Artificial teeth Based on the type of material used 1. Acrylic teeth 2. Porcelain teeth 3. Composite teeth Based on the occlusal form of teeth 1. Anatomic teeth 2. Semi-anatomic teeth 3. Nonanatomic teeth Anatomic teeth Semi-anatomic teeth Nonanatomic teeth Acrylic teeth Porcelain teeth Mounting of the casts in the articulator The sealed upper and lower cast with occlusion rim are positioned in the articulator with the help of modelling clay. The central pin should point the midline of the upper and lower occlusion rims. A thin coat of separating medium, such as Vaseline or petroleum jelly, is applied in the “V”-shaped notches in the upper cast with the help of a brush Dental plaster is mixed in appropriate proportion with the rubber bowl and mixing spatula. A portion of the mixed plaster is poured on the base of the upper cast. The mixed plaster is first made to flow into the “V”-shaped notch with the help of a wax knife The mixed plaster should be contoured according to the sides of the cast with the wax knife. When upper mounting is done, the articulator is inverted for mounting the lower cast Teeth setting Guidelines for anterior teeth setting are marked on the cast and the land area of the cast. I. The center of the incisive papilla (marked in red) II. A line is drawn along the midline of the cast through the center of the incisive papilla (marked in black). III. A perpendicular line is drawn to the above line through the center of incisive papilla till the land area (marked in blue; CPC line) IV. During setting of maxillary canine, the cuspid tip of the canine should be placed in line with this point The crest of the lower residual alveolar ridge is marked in red colour along the posterior aspect of the lower cast. A corresponding line is marked on the upper cast in blue Steps in placement of maxillary central incisor Step 1: Measure the maxillary central incisor in width and length. Step 2: Transfer the measurements into the occlusal rim. Step 3: Scoop out the wax. Step 4: Placement of the maxillary central incisor in relation to all three planes. Measure the mesiodistal width and cervicoincisal height of the maxillary central incisor tooth with a scale The mesiodistal width and the cervicoincisal height of the maxillary central incisor are marked on the upper occlusal rim with the scale and an outline is marked on the occlusal rim with a heated wax carver , The long axis of the central incisor (the blue line) is positioned parallel to the vertical axis (the red line) when viewed from the front The incisal edge of the maxillary central incisor is positioned in line with the anterior occlusal plane. The central pin of the articulator will point the mesioincisal line edge of the central incisor. The outline of the incisal edge of the maxillary central incisor should follow the outline of the maxillary occlusion rim when viewed occlusally. The position adjustments should be carried out when wax is soft When viewed from: Front: Long axis parallel towards the vertical axis. Side: Slopes labially about 15 degrees. Occlusal plane: Incisal edge is in contact with occlusal plane  Steps in placement of maxillary lateral incisor Placement of the maxillary lateral incisor in relation to all three planes. The cervicoincisal height and the mesiodistal width of the lateral incisor are measured, and the outline is marked on the maxillary occlusal rim. The required amount of softened wax is removed/scooped out with the heated wax carver from the occclusal rim The long axis of the lateral incisor (green line) is placed slightly inclined to the vertical axis (red line). The incisal aspect of the tooth is inclined towards the vertical axis when viewed from the front The incisal edge of the maxillary lateral incisor is placed slightly short of the occlusal plane (marked as yellow line). The incisal edge of the maxillary central incisor is placed in line with the occlusal plane (yellow line The incisal edge of the maxillary lateral incisor should follow the outline of the occlusal rim when viewed occlusally Front: Long axis slopes towards midline at incisal edge. When viewed from: Side: Slopes labially about 20 degrees. Occlusal plane: Incisal edge is 1 mm short of occlusal plane  Steps in the placement of maxillary canine Placement of the maxillary canine. The outline of the maxillary canine is marked on the maxillary occlusal rim with a heated wax carver, and the required amount of the wax is scooped out. The long axis of the maxillary canine (yellow line) should be parallel to the vertical axis (red line) when viewed from the front. The cervical part of the maxillary canine is placed more prominent when compared to the incisal aspect when viewed from the front The long axis of the maxillary canine (yellow line) should be parallel to the vertical axis (red line) when viewed from the side The cuspid tip of maxillary canine is placed in contact with the occlusal plane – yellow line  Maxillary canine follows the outline of occlusal rim, and the tip of the canine corresponds to the canine papillary line When viewed from: Front: Long axis parallel towards the tical axis. Side: Long axis parallel towards the ical axis. Occlusal plane: Cuspid tip is in contact with occlusal plane Completed maxillary anterior teeth – front Completed setting of maxillary anterior view. teeth – side Setting of mandibular anterior teeth Steps in placement of mandibular central incisor Step 1: Measure the tooth dimension. Step 2: Mark the desired outline. Step 3: Scoop out the wax. Step 4: Placement of the mandibular central incisor. The long axis of the tooth (blue line) is placed parallel to the vertical axis (red line). The incisal edge of the teeth is placed 0.5 mm above the occlusal plane (black line) when viewed from the front, The incisal edge of the mandibular lateral incisor is placed slightly labially when viewed from the side The incisal edge of the mandibular central incisor should follow the outline of the occlusal rim, and the incisal edge of the mandibular central incisor tooth should not cross over the land area when viewed occlusally  When viewed from: Front: Long axis inclines slightly towards the vertical axis. Side: Slopes labially. Occlusal plane: Incisal edge is 0.5–1 mm above the occlusal plane  Steps in placement of mandibular lateral incisor Placement of the mandibular lateral incisor. The long axis of the mandibular lateral incisor (green line) is placed parallel to the vertical axis (red line), and the incisal edge is placed 0.5–1 mm above the occlusal plane when viewed from the front, The incisal edge of the mandibular lateral incisor tooth is placed straight when viewed from the side  The incisal edge of the mandibular lateral incisor should follow the outline of the occlusion rim, and the incisal edge should not cross over the land area of the cast when viewed occlusally When viewed from: Front: Long axis inclines towards the vertical axis. Side: Slopes labially less than central incisor. Occlusal plane: Incisal edge is 0.5–1 mm above the occlusal  Steps in placement of mandibular canine Placement of the mandibular canine. The cuspid tip of the mandibular canine is placed 0.5–1 mm over the occlusal plane, and long axis of the mandibular canine is inclined mesially when viewed from the front, The cuspid tip of the mandibular canine slopes slightly lingually when viewed from the side The cuspid tip of the mandibular canine should follow the outline of occlusal rim, and the cuspid tip should not cross over the land area when viewed occlusally. The cuspid tip of the mandibular canine should follow the outline of occlusal rim, and the cuspid tip should not cross over the land area when viewed occlusally  When viewed from: Front: Long axis inclined towards midline. Side: Slopes lingually. Occlusal plane: Cuspid tip is 0.5–1 mm above the occlusal plane  Completed setting of maxillary and mandibular anterior teeth Complete the other side by following the same principles of teeth setting. The vertical overlap (over bite) between the maxillary and mandibular incisal edge should be 0.5–1 mm, and the horizontal overlap (over jet) between the maxillary and mandibular incisal edges should be 1–2 mm. The horizontal overlap should be uniform from left maxillary to right maxillary canine The mesial slope of the maxillary canine should overlap the distal slope of the mandibular canine as shown in  Posterior teeth setting Step 1: Mark a line on the occlusal surface of the lower occlusal rim, corresponding to the lower residual ridge and extend the line on the land area of the mandibular cast posterior to retromolar pad This line represents the central groove of the lower posterior teeth. Step 2: Mark a line on the occlusal surface of the upper occlusal rim, line connecting the midpoint of lateral incisor and the line on the land area posterior to the tuberosity which is exactly opposite to the line on the land area posterior to the retromolar pad Steps in placement of maxillary first premolar Placement of the maxillary first premolar in relation to all three planes. The outline of the maxillary posteriors is marked on the maxillary occlusal rim with a heated wax carver, and the required amount of wax is scooped out, The buccal cusp tip of the maxillary first premolar is in contact with occlusal plane (black line), and palatal cusp 1 mm short of the occlusal plane The long axis of the maxillary first premolar (blue line) is parallel to the vertical axis, The long axis of the maxillary first premolar (blue line) is placed parallel to the vertical axis (red line) when viewed from the front. When viewed from the front only small amount of the buccal surface should be visible when the patient smiles  When viewed from: Front: Long axis parallel towards the vertical axis. Side: Long axis parallel towards the vertical axis. Occlusal plane: Buccal cusp is in contact with occlusal plane and palatal cusp 1 mm short of occlusal plane  Steps in placement of maxillary second premolar Placement of the maxillary second premolar in relation to all three planes. The outline of the maxillary posteriors is marked on the maxillary occlusal rim with a heated wax carver, and the required amount of wax is scooped out. The buccal cusp tip and palatal cusp should be in contact with the occlusal plane – black line The long axis of the maxillary second premolar (green line) should be parallel to the vertical axis – red line. The buccal surface of the maxillary second premolar is barely visible when the patient smiles when viewed from the front. The buccal cusp of the maxillary second premolar corresponds with the buccal cusp of maxillary first premolar (blue line), and the palatal cusps of both the premolars correspond to the previous drawn line – yellow line  Front: Long axis parallel towards the vertical axis. Side: Long axis parallel towards the vertical axis. Occlusal plane: Both buccal cusp and palatal cusp is in contact with occlusal plane Steps in placement of maxillary first molar Placement of the maxillary first molar in relation to all three planes. The outline of the maxillary posteriors is marked on the maxillary occlusal rim with a heated wax carver and the required amount of wax is scooped out. The long axis of the tooth (yellow line) is inclined distally in relation to vertical axis (red line). Only the mesiopalatal cusp is in contact with the occlusal plane The maxillary first molar is slightly inclined when viewed from the front. When the patient smiles, very minimal buccal surface should be visible when viewed from the front the mesio- and distobuccal cusps correspond with the buccal cusp of second premolar (blue line) and the mesio- and distopalatal cusps correspond to the previous drawn line (yellow line).  When viewed from: Front: Long axis slopes buccally. Side: Long axis slopes distally. Occlusal plane: Only mesiopalatal cusp is in contact with occlusal plane  Steps in placement of maxillary second molar Placement of the maxillary second molar. The outline of the maxillary second molar is marked on the maxillary occlusal rim with a heated wax carver, and the required amount of wax is scooped out. The long axis of the maxillary second molar (blue line) is distally inclined in relation to the vertical axis (red line) when viewed from the front All the cusps are short of the occlusal plane (black line). The maxillary second molar is slightly buccally inclined when viewed from the front. The buccal surface of the maxillary second molar is barely visible when viewed from the front shows that mesio- and distobuccal cusps correspond with the mesio- and distobuccal cusps of first molar (blue line) and the palatal cusp corresponds to the previous drawn line (yellow line).  When viewed from Front: Long axis slopes buccally more steeply than first molar. Side: Long axis slopes distally more steeply than first molar. Occlusal plane: Only mesiopalatal cusp is nearest to occlusal plane  Steps in placement of mandibular first premolar Placement of the mandibular first premolar in relation to all three planes. The outline of the mandibular first premolar is marked on the mandibular occlusal rim with a heated wax carver, The long axis of the tooth is placed parallel to the vertical axis when viewed from the front. The mandibular first premolar is placed on maxillary canine and the maxillary first premolar The long axis of the mandibular first premolar should be inclined lingually when viewed from the front. The buccal surface of the tooth should be barely visible when viewed from the front There is no lingual intercuspation when viewed lingually  When viewed from: Front: Long axis parallel towards the vertical axis. Side: Long axis parallel towards the vertical axis. Occlusal plane: Lingual cusp below the horizontal plane, buccal cusp is 2 mm above the occlusal plane. Occlusal contact: Buccal cusp contacts the mesial marginal  Steps in placement of mandibular second premolar Placement of the mandibular second premolar in relation to all three planes. The mandibular second premolar is placed on the occlusion rim. The central fossa of the posterior tooth should be placed along the reference line (yellow line) marked The mandibular second premolar is placed parallel to the vertical axis when viewed from the front. The mandibular second premolar is placed between the maxillary first and second premolars, The mandibular second premolar is placed slightly lingually inclined when viewed from the front, The central groove of the lower mandibular second premolar is in contact with the palatal cusp of the maxillary second premolar when viewed lingually  When viewed from: Front: Long axis parallel towards the vertical axis. Side: Long axis parallel towards the vertical axis. Occlusal plane: Both cusps are about 2 mm above the occlusal plane Occlusal contact: The buccal cusp contacting the fossa between the two upper premolars  Steps in placement of mandibular first molar Placement of the mandibular first molar in relation to all three planes. The outline of the mandibular first molar is marked on the mandibular occlusal rim with a heated wax carver, and the required amount of wax is scooped out, The mandibular first molar is placed on the occlusion rim.The central fossa of the mandibular first molar is placed along the reference line (yellow line). The mandibular first molar is positioned in the occlusion rim below the maxillary first molar. The mesiobuccal cusp of the maxillary first molar (blue arrow) should rest on the mesiobuccal groove of the mandibular first molar (yellow arrow). The mandibular first molar is slightly lingually inclined. The buccal surface of the tooth is barely visible when viewed from the front, The mesiopalatal cusp of the maxillary first molar interdigitates with the central groove of the mandibular first molar  When viewed from: Front: Long axis lean lingually. Side: Long axis lean mesially. Occlusal plane: All cusps are at higher level than second premolar; buccal and distal cusps are higher than the other two Occlusal contact: The mesiobuccal cusp occludes in the fossa between upper second premolar and first molar  Steps in placement of mandibular second molar Placement of the mandibular second molar in relation to all three planes. The outline of the mandibular second molar is marked on the mandibular occlusal rim with a heated wax carver, and the required amount of wax is scooped out. The mandibular second molar is positioned in the occlusion rim such that the central fossa or groove of the second molar is in line with thereference line (yellow line) The mandibular second molar is placed on the occlusion rim below the maxillary second molar. The mesiobuccal cusp of the maxillary molar should rest on the mesiobuccal groove of the mandibular second molar, The mandibular second molar is positioned slightly lingually inclined, when viewed from the front. The buccal surface is barely visible when viewed from the front The lingual view shows that the central groove of the lower second molar is in contact with the palatal cusps of the maxillary first molar.  When viewed from: Front: Long axis lean more lingually. Side: Long axis lean more mesially. Occlusal plane: All cusps are at higher level than first molar ; buccal and distal cusps higher are than the other two. Occlusal contact: The mesiobuccal cusp occludes in the fossa between the two upper molars