Fourth Year Flashcards

Question

Describe the technique used for a upper anterior flabby ridge when support is poor (4)

Answer 1

Take preliminary impression in mucostatic impression plaster or “sloppy alginate” Cut window from flabby area and border mould First impression in paste of non-flabby area The take flabby area impression with fluid material Produces a cast of denture bearing tissues undisplaced at rest and therefore best possible retention

Answer 2

Relaxation techniques Distraction Hypnosis Sedation Local anaesthesia Desensitisation – give trays home with patient, provision of palatal training plates

Answer 3

Under extension at post dam – common! A loose upper drop to touch posterior tongue and induces gag reflex Overextension at post dam – rare! but many pt.’s don’t agree Excess occlusal vertical dimension Muscle balance – tongue space encroachment / lower occlusal plane high Thickness of bases

Answer 4

Mandible is suspended from the skull by muscles, ligaments, vessels, nerves, soft tissues. Jaw movement in 3D space – maxilla and movement is limited by muscles, TMJ, teeth Basic movements Vertical plane – open and close Lateral plane – RHS and LHS Antero-posterior plane – protrusion, retrusion Functional movement almost always a combination of translation and rotation but may be purely rotational.

Answer 5

Mastication (an intermittent rhythmic act in which the tongue, facial and jaw muscles act in coordination to position the food between the teeth, cut it and prepare it for swallowing) Speech Swallowing Respiration Emotional expression Parafunction activities: clenching, grinding, lip/cheek biting, thumb sucking, nail biting

Answer 6

Muscles of mastication TMJ Teeth

Answer 7

A dynamic concept describing the integrated action of the components of the masticatory system that control tooth contact during function and dysfunction.

Answer 8

Occlusion in natural teeth: Independent movement and retained by PDL. Fine neuromuscular control by proprioception from PDL, TMJ, M.O.M, tongue. Anterior incising involves separation of the posterior teeth. Lateral excursions produce WS contacts on canines/premolar/both (canine guidance or group function) and separation of teeth on the non-WS. Malocclusions – posterior contact during anterior incision or non-WS contact – can cause problems if occlusion not checked during restorations or prosthetics. Complete denture occlusion: Teeth are all linked together on a denture base and are easily displaced during function. Proprioception is much reduced and comes from TMJ, mucosa DBA, muscles of mastication and tongue. Denture bearing mucosa is compressible and likely to be uneven. Stability during tooth contact is dependent on “balanced occlusion/articulation”.

Answer 9

- Stability ND teeth are independent and firmly attached to bone. AD united and rest on mucosa. - Comfort ND biting force greater (x5) than AD as pain threshold of mucosa easily exceeded. - Chewing efficiency ND>AD (x6 number of chewing strokes)

Answer 10

Rest vertical dimension (rest face height) – the vertical dimension of the lower face with the mandible in the rest position. Occlusal vertical dimension (occlusal face height) – the vertical dimension of the lower face with the teeth in centric occlusion. Interocclusal distance (free way space) = RVD – OWD FWS is a range of 2-4mm at the incisors.

Answer 11

RCP = relation of the mandible to the maxilla with the mandible in its most retruded position at a prescribed occlusal vertical dimension.

Answer 12

Bilateral balanced articulation – bilateral simultaneous contact of teeth in RCP and during excursions. Monoplane (non-anatomical) occlusion – ICP and RCP correspond but no attempt to achieve contact in excursions. Lingualised occlusion – where the maxillary palatal (lingual) cusps articulate with the mandibular occlusal surfaces in RCP and with cuspal inclines in excursions (upper buccal cusps never touch).

Answer 13

The simultaneous even occlusal contact between maxillary and mandibular teeth bilaterally or anteriorly-posteriorly.

Answer 14

The simultaneous bilateral, or anterior-posterior, occlusal contacts between maxillary and mandibular teeth during the movement from one balanced occlusion (i.e. during function) to another.

Answer 15

↑ efficiency of the dentures by making them more stable and freed from tipping on unbalanced (retention, stability, masticatory function, generalised satisfaction). It distributes the occlusal load over the whole denture bearing area and this reduces the risk of alveolar trauma and resorption (occlusal force distribution, comfort). It increases the patient’s confidence by making sure that the dentures are re-seated evenly if they become dislodged (stability, comfort, generalised satisfaction). Uses posterior teeth with cuspal anatomy (masticatory function, aesthetics).

Answer 16

Record the correct RCP relationship of the jaws and transfer this to an articulator capable of reproducing that patient’s mandibular movements i.e. at registration stage. By setting the teeth up in balanced articulation, using the factors governing balanced articulation, on the prescribed articulator (usually an AV articulator). Use and understand those factors (Hanau’s Quintet) influencing tooth position to achieve a set up in balanced articulation.

Answer 17

Reproducible (because it is a border position). Patients can easily accommodate to it (via neuromuscular feedback from proprioceptors in TMJ, muscles of mastication, denture bearing mucosa). To set up a balanced articulation occlusion we must record the most posterior position achievable as the average value articulator cannot reproduce ‘backwards’ movements.

Answer 18

Record RCP with registration rims Prescription to technician – “please provide balanced articulation set up on AV articulator for try-in” Technician completes trial set up Clinician assesses trial set upon articulator and in the mouth

Answer 19

Incisal guidance 10 / 15 Condylar guidance 30 / 35 Cuspal angles (height) 20 / 25 Plane of occlusion ala-tragal plane orientation Compensating curves Spee / Wilson (change effective cusp height)

Answer 20

Posterior plane surfaces separate on protrusion (Christensen’s Phenomenon) Need to introduce a curve to the occlusal plane antero-posteriorly (and laterally) to maintain cuspal contact during excursions.

Answer 21

Lip support: tooth position – up to 1cm ahead of incisal papilla tooth inclination - 90° columella-philtrum angle Good lip support is achieved by correct anterior placement of incisors – not flange thickness. Incisal level: at rest and function - show 1 or 2 mms below lip at rest, nearly all the crown when smiling but customise to patient Anterior and posterior occlusal plane: trim using the Fox’s occlusal plane indicator. Anterior occlusal plane – parallel to interpupillary plane Posterior occlusal plane – parallel to ala-tragal line (camper’s plane), through tragus of the ear to lower border of ala of nose This allows the occlusal forces applied to the dentures to be perpendicular to the alveolar ridges which improves stability Lower occlusal plane – should be below the resting level of the tongue, runs into the RM pad about halfway up Width and form of arch: harmonise to patient facial profile, no posterior buccal corridor Mould and shade: customise to patient Average mould statistics from 433 subjects on mean age 16years Make sure to mark the centre line and the premolar area when patient is smiling – midline placed in middle of exposed rim at rest/smile - ignore nose.

Answer 22

Assessment of lower face height by measurement Willis gauge or callipers with skin dots (rest vertical dimension minus 2-4 mms to provide an interocclusal rest distance. If using Willis gauge have upper rim/denture in place. Measure existing dentures OVD as a guide as well. Assessment of appearance Insufficient OVD, too much IOD = overclosed. Gives only a poor appearance (“popeye”) Excessive OVD, too little IOD = overopen. Gives poor appearance and affects the function of the denture. discomfort in facial musculature as no rest from tooth contact trauma and pain in denture bearing tissue esp. lower clicking of teeth during speech Visual assessment during speech: aim to provide a minimum speaking space of 1 or 2 mms between the incisal edges when pronouncing sibilant sounds i.e. ‘s’sounds – “Mississippi, sixty six” Assess parallelism of ridges when mounted on articulator at trial stage

Answer 23

Mark centre line (of face!) Mark premolar guide lines to test reproducibility of RCP Cut V-shaped wedges in premolar region of upper and Vaseline rim Place registration paste on lower At the end of the registration – check the reg rims on the model. Ensuring clearance of the cast and rims i.e. no premature contact in the recorded RCP. For example, premature contact in the RM pad or hamular notch region of rims.