fixed pros guidelines lecture.pdf

8/18/2019 fixed pros guidelines lecture.pdf

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School of Dentistry and Health sciences

Fixed ProsthodonticsGuidelines at CSU

Dr. Bilal El Masoud

BDS, GradDipClinDent(Melb), DCD(Melb),

FRACSD, FRACDS(Pros), ADC(Australia)CSU


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Case selectionGeneral case selectionThe following cases shou ld not be managed in the

undergraduate student clinics:

• Patients undergoing chemotherapy or radiotherapy.• Patients with severely impaired immunity.• Patients suffering from rare syndromes that require

specialist management.

• Patients with active airborne infections (eg. active TB,SARS, H1N1).

• Patients with medical conditions that render themincapable of withstanding lengthy dental appointments.


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Cases to avoid in Fixed Prosthodontics• Patients whose prosthodontic treatment plan has not

been approved. This is particularly important if a crownis to serve as an abutment for a partial RDP.

• Patients with unrealistic aesthetic expectations oranatomical considerations that compromise aesthetics(e.g. a high ‘lip line’).

• Patients with significant loss of VDO, severe dentalattrition, short clinical crowns or an underlying

symptomatic tm joint condition (e.g. painful tm joint‘locking’ or ‘clicking’).


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Cases to avoid in Fixed Prosthodontics• Patients best served by pre-prosthodontic surgery (e.g. ‘crown

lengthening’ or alveolar ridge augmentation) or orthodontictreatment. In such cases patients should be advised of theirtreatment options and specialist referral pathways, and informed

consent must be received before proceeding with any alternativemanagement that is deemed within scope of practice in theundergraduate dental clinic. Only rarely would an advanced (Year 5)undergraduate student be permitted to manage a case requiringreferral for pre-prosthetic oral or periodontic surgery.

• Patients best served by fixed prosthodontic treatment but where the

condition of any core material or remaining coronal tooth structurehas not been assessed or where the excavation of any caries prior tocore placement has not been recorded in the clinical notes.


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Rule

• Once any prosthodontic treatment plan has

been approved, it is desirable (but not

always possible) that the student ismentored through the treatment by the

same clinical tutor.


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Treatment commencementExamination, diagnosis and treatment planning

forms are available and it is mandatory for thestudents to fill the forms and obtain signatures

from the supervising staff before commencingany treatment.

Lab forms need to be filled by the student and the

tutor needs to insure that all the appropriatesections are filled and all the necessaryinstructions are clear.


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Primary impressions: For any fixed pros treatment thestudents must obtain primary impressions in order tofabricate study casts. These are taken using a stocktray in Alginate impression material. The impressions

need to be disinfected and poured as soon as possibleto minimise distortion, within 15 minutes to a maximumof 1 h. If that was not achievable then the impressionmust be repeated.

Primary bite registration: Wax bite material is used to

relate both casts together and face bow record is alsotaken to mount the casts on an articulator .



Assessment of the mounted casts, treatmentplanning and diagnostic waxup is thenperformed to re-establish the lost tooth structure. APVS PUTTY INDEX is then fabricated that will atleast cover one tooth on either side. In cases ofbridges a plastic tooth of suitable size is then usedto fill up the gap area and the index needs to cover

all abutments in addition to one tooth on either sideof the abutments.



Fabrication of special trays (light cured or

self cure)

• They need to be prepared at least a daybefore and an adhesive layer is applied well

before the appointment (minimum 30

minutes).• For maxillary special trays the palate does notneed to be covered to reduce the chances of

gagging. (This is only for fixed pros)



Tooth preparation steps:• Adequate anaesthesia if needed.• For All Ceramic Crowns a 1 mm shoulder with an internal rounded

angle (radial shoulder) is the recommended. In addition a 1.5-2mm

occlusal reduction is required for posterior teeth and a 1.5mm incisalreduction for anteriors. PFM Crowns require a 1.2mm facial reduction(shoulder) and 0.5-0.8mm lingual reduction (chamfer).

• Check the amount of clearance from the opposing dentition at maximumintercuspation and at excursions (Extremely important)

• Post and cores require conservative preparation and should assure thelack of undercuts. GP could be removed by heated instruments or

Gates Glidden. Para post drills ARE NOT to be used in handpieces andshould be utilized manually to create the post space. (PA shouldalways be taken to assess the remaining apical seal)



Final impression• In cases of gingival recession and open embrasures please insure to

block these embrasures using CAVIT or WAX before taking theimpression.

• Achieve a dry field and use a double retraction cord technique (singleretraction cord technique in aesthetic zones and thin biotype cases). Useretraction cords in areas where the finish line is below the gingivalmargin. Impregnation of the retraction cord using Aluminium Chloride isaccording to the preference of the tutor.

• Addition type PVS is the material to be used. At CSU we do not usepowdered gloves but in case you were using them do not mix the putty

material using your gloves.• The standard single stage impression technique is followed atCSU.



• The material needs to remain inside the mouth for at least5 minutes to insure that it has reached its final set.

• Check the impression for air bubbles and that there are no

drags that could affect the accuracy of the impression.(The tutor needs to sign off the impression)

• Insure that all retraction cords are removed.• For Post/Core impressions please use the periodontal

probe to measure the length of the impression post stickingout of the impression and compare it with the post space

depth inside the tooth before sending out the impressionfor casting.

• All impressions need to be disinfected.



Bite registration is taken using a PVS

material if most of the teeth are available.

In cases were the crown is fabricated oncasts which cannot be made stable due to

minimal number of tooth contacts a

separate appointment for bite registrationis made using bite records. Take a face

bow record at this stage.



Temporization is performed using a

BisGMA material. Insure that all the

margins are intact and that there are nopositive margins. Use TempBond as your

provisional cement, however if the final

restoration is going to be adhesivelybonded to the tooth structure you need to

use an Eugenol free temporary cement.



Try –in stage

• On the cast, you need to check that the crown is fitting on thedie without any gaps or rocking. Check the emergence profile ofthe crown and insure that it is not bulky. Also check the fittingsurface for any metal bubbles. Always check that the lab hascomplied with your requests.

• Always make sure that you have an untouched die that could beused to perform a quality control step.

• Once happy with the crown proceed to the clinical steps. Checkif the crown is fully seated. If not the first thing to check is thecontact points. If tight use graphite markers, articulating papersor fit checking spray material to identify the tight spots. Adjustthem slowly until the shim stock can be withdrawn with

resistance. Also check that the lab has not damaged the diemargin and created a lip of metal that is not allowing the seatingof the crown.



Try –in stage

• Then check the margins for fit (take a precementation PA) andgaps and the crown for rocking.

• Check the occlusion using a shim stock and articulating papers.

• Check for shade and obtain consent for cementation from thepatient. Do any necessary adjustments or send it back to the lab

if needed.

• Proceed to the cementation stage.



Cementation stage:

• Achieve a dry environment.• Do not over dry your preparation.• Use the appropriate cement for the crown type you are using:

•PFM crown/ Metal crowns: use GI luting cement or Resin

Modified Glass Ionomer Cement (preferable)

• Ceramic crowns and ceramic inlays and onlays: IPS e.max,use an adhesive cement under rubber dam. (Don’t forget the

need for HF acid etching)

• Ceramic Zirconia crowns: use resin modified glassionomomer cement.



• Strictly follow the cementation steps provided by themanufacturer as different cements need deferent

steps. (check what is available at your clinic before

your cementation appointment)

• Insure the removal of all excess cement.• Recheck occlusion and take post cementation x-ray.

• Provide post operative instructions.



Review appointment:

• Check oral hygiene• Check occlusion• Aesthetics• Excess cement.

fixed pros guidelines lecture.pdf

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