Digital Dentures PDF

Digital dentures- 1 computer-aided design and computer-aided manufacturing (CAD-CAM) technology 2 functional impression is not possible as the technique is image-based. 3 a partial denture is designed in a virtual space based on the data obtained ➡️by scanning a defini...

Digital dentures- 1 computer-aided design and computer-aided manufacturing (CAD-CAM) technology 2 functional impression is not possible as the technique is image-based. 3 a partial denture is designed in a virtual space based on the data obtained ➡️by scanning a definitive cast fabricated with a conventional functional impression digital fabrication method advantages :-. 1 electronic surveying performed to determine the path of insertion and removal and control the undercut amount through computation in a more straight forward and accurate. 2 The undercut with a desired gauge may be formed quantitatively at the position 3 the design data may be saved for future use 4 total time of prosthesis fabrication is substantially reduced by eliminating some processes, including cast duplication and investment cast fabrication. 5 multiple prosthesis patterns may be simultaneously produced in a short time frame Clinical steps 1 Intraoral functional impressions, including border molding, 2 a definitive cast is obtained. 3 the cast is scanned using a laboratory scanner 4 files are extracted and loaded onto the CAD software. 5 The framework of the RPD is designed by setting a surveying axis and computing the undercut to determine an ideal path of insertion and removal 6 The appropriate components, including the major connector, clasps, rests, proximal plates, and finish line, are designed. 7 Based on the completed design, a pattern was printed in resin (VisiJet M3 Dentcast; 3D Systems) using a rapid prototyping machine (ProJet DP 3000; 3D Systems) 8 Pattern is invested, eliminated, and cast to generate the RPD framework. 9 The RPD was completed by using the conventional method, using heat polymerized resin and artificial teeth. 10 adjustments are made to ensure that the rests are seated on the rest seats of the abutment teeth 11 denture is delivered to the participant. MCQs ‫مهمة‬ 1. What is the rapid prototyping procedure used in dentistry? a. To fabricate complete dentures b. To fabricate partial dentures C. To fabricate implant-supported restorations D All of the above 2. Which study evaluated the accuracy of digital RPD on a larger number of participants? A Preliminary study b. Clinical study c. Comparative study d. None of the above. 3. Which technology is used for designing and manufacturing dental prostheses? A CAD-CAM technology b. Rapid prototyping technology c. 3D printing technology d. None of the above 4. What is the main limitation of using digital RPD? a. Reduced accuracy and precision b. Increased fabrication time and cost c Limited clinical effectiveness and accuracy d. None of the above 5. Which type of prosthesis patterns can be simultaneously produced using digital RPD? a. Only one prosthesis pattern at a time b Multiple prosthesis patterns in a short time frame c. Only fixed dental prostheses patterns d. None of the above 6 the use of scanner for RPD fabrication is ‫وزاري‬ A time consuming B more accurate C useful for final impression D economic E All of above Horizontal Jaw Relations 1 Centric occlusion: The occlusion of the opposing teeth when the mandible is in centric relation. 2 Centric relation: The maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective disks with the complex in the anterior superior position against the shapes of the articular eminencies. Methods used to position jaw in centric relation: 1 Having the patient completely relax the mandible while the clinician gently shakes the mandible up and down. 2 Placing the tip of the tongue in the top and back of the mouth. 3 Telling the patient to "Stick out the upper teeth”. 4 Tipping the chair and patient back to allow gravity to help position the mandible. 5 Using a mirror so that the patient can see the CR mandible position Note. The maxillary master cast has now been properly placed on the articulator using a face-bow recording 1 The other hand is used to help guide the patient to centric relation position. Care should be exercised to avoid displacing the mandibular record base in the posterior direction. 2 the centric relation position is somewhat dependent on head posture, the head should be held fairly upright 3 The position of the dentist's hands is an important factor in making accurate centric relation records and maintaining record bases in their correct position 4 The non-dominant hand is inverted and placed in the mouth so that the soft tissue of the thumb and index fingers lies on the opposing buccal surfaces of the maxillary and mandibular occlusion rims, between the occlusal surfaces in the first molar region Vertical Jaw Relationships Maxillomandibular relationship record: a registration of any positional relationship of the mandible relative to the maxillae; these records may be made at any vertical, horizontal, or lateral orientation. Vertical dimension: the distance between two selected anatomic or marked points (usually one on the tip of the nose and the other on the chin), one on a fixed and one on a movable member Vertical jaw relation can be recorded in two positions: 1- Vertical dimension at rest position (VDR) 2- Vertical dimension at occlusion (VDO) Rest vertical dimension (physiologic rest position): The distance between two selected anatomic or marked points(usually one on the tip of the nose and the other on the chin) when an individual is resting comfortably in an upright position and the associated muscles are in a state of minimal contractual activity Vertical dimension of occlusion: the distance between two selected anatomic or marked points (usually one on the tip of the nose and the other on the chin) when the teeth in maximal intercuspal position or occlusal rims are in contact in centric occlusion Interocclusal rest distance (freeway space): the difference between the rest vertical dimension and the occlusal vertical dimension. VDR – VDO = Freeway space (2-4mm) Note. (the vertical dimension at occlusion should always be 2-4 mm lesser than the vertical dimension at rest Errors in vertical dimension are the first to produce severe discomfort in the temporomandibular joint, the muscles of mastication and the joint will be strained. Factors Affecting Vertical Jaw Relation 1-Teeth 2- Musculature Importance of Vertical Jaw Relation 1. Functional roles include: mastication, respiration, deglutition, phonetics. 2. Psychological role 3. Esthetic role. 4. Comfortable role by maintaining health of tissue, mucosa bones, muscles and (temporomandibular joint) The following methods are used for recording VDR: 1. Facial measurements after swallowing and relaxing. 2. Tactile sense. 3. Measurement of anatomic landmarks. 4. Speech or Phonetic. 5. Electro-myographic method. 6. Facial expression Vertical Dimension at Occlusion Mechanical methods A. Ridge relation: 1) Distance from the incisive papilla to mandibular incisors 2) Parallelism of ridges. B. Pre-extraction records: 1) Profile photographs 2) Articulated casts 3)Facial measurements. C. Measurement from former dentures Physiological Methods 1 Power point. 2 Using wax occlusal rims. 3 Physiological rest position. 4 Phonetics. 5 Aesthetics. 6 swallowing threshold ‫مالحضات‬ 1The incisal edge of the maxillary central incisor is an average of 6 mm below the incisive papill 2 the average vertical overlap of the opposing central incisor is about 2 mm 3 interocclusal space is present between the rims. It should be 2-4mm in premolar regions The most frequently used tests that aid the dentist in establishing the correct VDO by means of occlusion rims are: 1. Visual observation of the space between the rims when the mandible is in its physiological rest position. 2. Judgment of the overall esthetic facial support. 3. Phonetic tests that include observations when the “s” sound is enunciated accurately and repeatedly—the average speaking space Effects of increased vertical relation: 1. Speech problems. 2. Sensation of bulky dentures. 3. Premature contact & clicking during function. 4. Increased rate of residual ridge resorption. 5. T.M.J & muscle pain & fatigue. 6. Poor esthetic like separated lips & display of the teeth. 7. Inability to open the mouth widely. 8. Loss of biting power. 9. Difficulty in swallowing. 10. Increased volume or cubical space of the oral cavity Effects of decreased vertical relation: 1. Poor esthetics like thin-lipped appearance, prominence of mandible and chin. 2. Presence of excessive wrinkles & folds in corner of mouth which may lead to angular cheilitis. 3. loss of biting power & decreased chewing ability 4. muscular fatigue& pain in T.M.J region 5. cheek biting 6. Neuralgia or other features. 7. Decreased volume or cubical space of the oral cavity. MCQs ‫المهمة‬ 1 freeway space A the space between the teeth at rest B the difference between the rest vertical dimension and the occlusal vertical dimension All C also it is called Interocclusal rest distance D of the above E none of the above 2 Increased vertical relation results in a. cheek biting b. Loss of biting power. c. Poor esthetic like separated lips & display of the teeth. D b and c. e. Poor esthetic like thin-lipped appearance. 3 decreased vertical relation results in a. Clicking during function. b. Increased rate of residual ridge resorption. C Difficulty in swallowing. d. Poor esthetic like thin-lipped appearance. e. Poor esthetic like separated lips & display of the teeth. 4 For registering centric relation which of the below should achieve? a. patient completely relax b. Dentist gently shanks the mandible up and down c. ask the patient to place the tip of tongue in back of mouth d. tell the patient to stick out upper teeth e All of the above 5 The vertical dimension of occlusion should be a. Equal to vertical dimension of rest b. More than vertical dimension of rest by 2-4 mm c Less than vertical dimension of rest by 2-4 mm d. Less than vertical dimension of rest by 6 mm e. None of the above 6 Vertical dimension: a. the distance between two selected anatomic or marked points (usually one on the tip of the nose and the other on the chin), one on a fixed and one on a movable member. b. the distance between two selected anatomic or marked points (usually one on the tip of the nose and the other on the chin) when the teeth in maximal intercuspal position. c. The distance between two selected anatomic or marked points (usually one on the tip of the nose and the other on the chin) when an individual is resting comfortably in an upright position. D All of the above. e. None of the above.