Dental Surveyor PDF

Dental Surveyor Determines parallelism of two or more surfaces of a tooth or other parts of a cast of the dental arch Two types: 1. Electronic – reserved for large dental laboratories 2. Mechanical- Moved manually o Ney Surveyor: has a non-swivel horizontal arm o Jelenko surveyor: has a swiveling ho...

Dental Surveyor Determines parallelism of two or more surfaces of a tooth or other parts of a cast of the dental arch Two types: 1. Electronic – reserved for large dental laboratories 2. Mechanical- Moved manually o Ney Surveyor: has a non-swivel horizontal arm o Jelenko surveyor: has a swiveling horizontal arm and it has a spring mounted paralleling tool (Marathon 103 surveyors are upscale Jelenko’s that has a place for optional handpiece attachment) Parts of a Dental Surveyor Platform – part of the Surveyor of which the base is moved Vertical Arm (or upright column) – that supports the structure C. Horizontal Arm – the part from which the Surveying Tools suspend Survey Arm – the part that holds the survey tools Mandrel – for holding the special tools Tools – which are used for Surveying Table– to which the Cast is attached Base – on which the Table swivels Tools (listed with sequence of use) Analyzing Rod o Rigid metal rod used for diagnostic purposes in the selection of the path of placement o Determines undercut areas prior to scribing the height of contour with a carbon marker Carbon Marker o Used for actual marking of the survey lines on the cast o A metal shield holder is used with the carbon marker to protect the carbon marker from breaking Undercut Gauges o Measure the extent of the undercuts on abutment teeth that are being used for clasp retention o Three gauges: 0.01, 0.02, and 0.03 inch o Undercut dimensions are measured by bringing the vertical column of the gauge in contact with a tooth and then moving the surveying arm up or down until the tooth is in contact with the terminal tip Wax Trimmers o Knife-like instrument used for trimming excess wax which has been placed to block out undesirable undercut areas in such a way that it is parallel to each other and to the predetermined path of placement or insertion. Definitions Height of Contour o The Facial or Lingual bulge o Point of greatest convexity of the crown outline o Usually in middle 1/3 or cervical 1/3 of the tooth NOT incisal or occlusal 1/3 Tooth Undercut o Portion of tooth that lies between height of contour and gingiva (only if that portion is of less circumference than the height of contour) o Undercuts exist because of the natural tooth morphology and contours The Ideal Requirements for a Successful RPD Careful evaluation of the patient’s study cast Dental surveyor used to aid in examination of the study cast Procedure is called surveying 5 Main Objectives: 1. Easily inserted and removed by the Patient 2. Resists dislodging forces 3. Esthetically pleasing 4. Avoids unnecessary food traps 5. Minimizes plaque retention Surveying Determination of the parallelism of two or more surfaces of tooth or other parts of a cast of the dental arch “Survey” procedure is locating and delineating the contour and position of abutment teeth and associated structures BEFORE designing RPD Objective of Surveying: Modifications that will fabricate a RPD that can be easily inserted in the mouth and retained in place Purposes of Surveying Diagnostic Casts: 1 ) Determines most desirable path of placement that will eliminate or minimize interference to removal and placement. 2.) Identify proximal tooth surfaces that need to be parallel to act as guiding planes during placement and removal. 3.) Locate and measure areas of teeth that may be used for retention 4.) Determine whether tooth and bony areas of interference needs elimination surgically or need different path of placement 5.) Determine most suitable path that will permit locating retainers and artificial teeth to the best esthetic advantage 6.) Permit an accurate charting of the mouth preparation to be made. 7.) Delineate height of contour (survey line) on abutment and locate areas of undesirable tooth undercut (must be eliminated) 8.) Record cast position in relation to selected path of placement for future reference. This may be done by locating three dots (tripods) Advantages of a single path of placement (insertion) Allows insertion and removal of the prosthesis without interferences Helps to direct the force along the long axis of the tooth Frictional retention is provided Minimizes torque on the abutment teeth Cross arch stabilization Equalizes retention Guiding Planes What are they? A. Flat surfaces parallel to the path of insertion B. Represents the initial contact of RPD C. Help to stabilize, control and limit the movement of the RPD Guiding Planes – two or more vertically parallel surfaces on abutment teeth and/or fixed dental prosthesis oriented in direction of path of placement and removal of the RPD, maxillofacial prosthesis, or an overdenture. When RPD is properly designed to have passive guide planes, the patient can easily place and remove RPD in one direction Undesirable Undercuts Undercuts can either be: o Desirable undercut – useful to retain a RPD against dislodging forces o Undesirable undercut – interfere with placement (insertion) and removal of the prosthesis or produce damaging effects Undercuts eliminated by: o Block out wax o Preparation and alteration of tooth surfaces (within a limit) o Crown restoration in which the tooth surface can be reshaped to serve the RPD functions and requirements Blocking Out o After path of placement and location of undercuts is established on master cast, any undercut areas that will be crossed by rigid parts of RPD must be eliminated with block out o Includes not only the areas crossed by RPD framework during seating and removal but also: 1. Ledges on which clasp patterns are to be placed 2. Relief needed below connector to prevent tissue impingement 3. Relief needed for the attachment of denture base to the framework. 4. Areas not involved are blocked out for convenience Work Authorization for RPD Lab Directions Form contains written directions for lab procedures to be performed for fabrication of dental restorations or prosthesis Work authorization completed by a dentist who specifically prescribes the authorized work and when it is properly executed It is an effective channel of communication between the dentist and laboratory Must provide quality instructions to assure the quality of the restoration or prosthesis is fabricated. *** Information Contained in the Work Authorization 1. Dental lab: name and address 2. Dentist initiating work: name and address 3. Patient ID 4. Date of work authorization 5. Completion date of work request 6. Specific instructions 7. Registered license number of dentist 8. Signature of dentist Function of Work Authorization (4) 1. Instructions for lab procedures to be accomplished and implies an acceptable level of quality for the services rendered 2. It provides a means for protecting the public from illegal practice of dentistry 3. It is a protective legal document for the dentist and the laboratory technician 4. It completely delineates (defines) the responsibilities of the dentist and the laboratory technician Characteristics of an Effective Work Authorization MUST be legible, clear, concise, and readily understood (lab technicians are NOT decoding experts) Dentist must provide sufficient information to enable the technician to understand and execute the request o No single work authorization form is adequate to complete ALL the phases in the fabrication of RPD*** o A separate form should be used for each phase of fabrication. *** Definitive Instructions are REQUIRED on a Work Authorization Form Work authorization form should be designed with only minimum amount of writing, necessary to provide thorough instructions o A printed list of materials or specifications can be provided that only require a checkmark or a fill-in the blank box. o A space should be provided to determine the framework (metal- if metal is selected Ex: cast gold type IV, chromium-cobalt or titanium) or acrylic. o Space is provided for the dentist’s selection of teeth (location, number, size, material they are made of) Words on the form display respect and courtesy to the lab technician such as “please” and “Thank-you.” o Good work authorization should display clarity and SIMPLIFY as much as possible for correct execution*** o Instructions should be SPECIFIC and leave no doubt as to what you expect and require*** o Copies are made for lab technician and for dentist to retain (patient’s record)* Work Authorization Legal Aspects and Responsibilities DENTIST is responsible for ALL phases of RPD fabrication *** Lab technician is responsible ONLY to the dentist instructions and NEVER to the patient *** If dentist delegates authority to an auxiliary team member, the ultimate responsibility remains with the DENTIST *** In lab we are making Kennedy class III RPD