4.Mouth Preparation

8/12/2019 4.Mouth Preparation

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Even on caries-free teeth, an existing restorationmay not be a suitable foundation.

Preparation design is different for a foundationthan for a conventional restoration, particularly

regarding the placement of retention.Generally, when a crown is needed, the dentist

should plan to replace any existingrestorations.


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FONDATION RESTORATIONS

A foundation restoration, or core, is usedto build a damaged tooth to ideal anatomicform before it is prepared for a crown.


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It should provide the patient with adequate

function and should be contoured and finished tofacilitate oral hygiene.

Subsequent tooth preparation is greatly simplifiedif the tooth is build up to ideal contour.

Selection of the foundation material depends onthe extent of tooth destruction, the overalltreatment plan, and operator preference.

Adhesive retention may be helpful in preventingloss of the foundation during tooth preparation.


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The placement of a foundation restoration depends on the extent of damage to the toothand should always be designed with the definitive restoration in mind. A, Cement. This issuitable when damage is minimal. B, Amalgam. C, Pin-retained amalgam. D, Cast gold.

E, Post-and-core.


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DEFINITIVE PERIODONTALTREATMENT

Unless a patient's existing periodontaldisease has been properly diagnosed

and treated, fixed prosthodontics isdoomed to failure


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Certain specific periodontal procedures may be

indicated to improve the prognosis of arestoration: Mucosal Reparative Therapy Free Autogenous Gingival Graft Laterally Positioned Pedicle Graft Coronally Positioned Pedicle Graft Subepithelial Connective Tissue Graft

Crown- Lengthening Procedures


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CROWN- LENGTHENING PROCEDURES

Surgical crown lengthening or extension may beindicated to improve the appearance of ananterior tooth or when the clinical crown is too

short to provide adequate retention without therestoration's impinging on the normal soft tissueattachment or biologic width.


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The term biologic width refers to the combined connectivetissue-epithelial attachment from the crest of thealveolar bone to the base of the gingival sulcus

This attachment averages approximately 2 mm in width,and any restoration that impinges on it may cause boneloss because of the effort of the host to maintain the 2mm distance.

If impingement occurs in an interproximal area, it canlead to problems with plaque control and possibleosseous resorption.


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DEFINITIVE OCCLUSALTREATMENT

Mouth preparation often involvesreorganization of the patient's occlusion,typically to make intercuspal positioncoincident with centric relation and removeeccentric interferences


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When selective reshaping of the natural dentition

is being considered, it is important to rememberthat this is a purely subtractive procedure (tissue isremoved), and it is limited by the thickness of the

enamel. Obviously, before any irreversiblechanges are made in the dentition, a carefuldiagnosis must establish whether restorations

will be needed.

Two sets of articulated diagnostic casts arerequired for diagnostic occlusal adjustment.


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Occlusal adjustment needs to be undertaken ina logical sequence to avoid repetition andimprove the efficacy of treatment.

1. Elimination of Centric Relation interferences2. Elimination of Lateral and Protrusive

Interferences.


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TREATMENTPLANNING


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Treatment planning consists of formulating alogical sequence of treatment designed to

restore the patient's dentition to goodhealth, with optimal function and

appearance.The plan should be presented

in written form and should be discussed in

detail with the patient.


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Successful treatment planning is based on

proper identification of the patient's needs.

Treatment is required to accomplish one or

more of the following objectives: correctingan existing disease, preventing futuredisease, restoring function, and improving

appearance.


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Selection of Abutment Teeth

Assessment of Abutment Teeth

Radiographs are made, and pulpal health isassessed by evaluating the response tothermal and electrical stimulation.


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The ability of the abutment teeth to accept applied

forces without drifting or becoming mobile mustbe estimated and has a direct influence on the

prosthodontic treatment plan.

These forces can be particularly severeduring parafunctional grinding and clenching.


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Endodontically Treated Abutments.If a tooth is properly treated endodontically, it can

serve well as an abutment with a post and corefoundation for retention and strength.

Care is needed to obtain maximum retention forthe post and core.Sometimes it is better to recommend removal of a

badly damaged tooth rather than to attemptendodontic treatment.


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Definition

A post and core is a dental restoration foran endodontically treated tooth used tosufficiently build-up tooth structure for

future restoration with a crown when thereis no enough tooth structure to properlyretain the crown.

Post and cores are therefore referred to asfoundation restorations .

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R o o t Su r f ac e A r ea

The root surface area of potential abutmentteeth must be assessed when planning

treatment for fixed prosthodontics.


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Ante's law

Ante suggested in 1926 that it was unwiseto provide a fixed partial denture when theroot surface area of the abutment was lessthan the root surface area of the teethbeing replaced.


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Authors have confirmed that abutment teethwith limited periodontal bone can

successfully support fixed prostheses.

Antes law is useful for determining theprognosis of fixed partial denture.


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Root Shape and Angulation

the shape of the roots and their angulation shouldbe considered.

A molar with divergent roots will provide better

support than a molar with conical roots and littleor no interradicular bone.

Similarly, a well-aligned tooth will provide bettersupport than a tilted one.


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P er i o d o n t al D i s e as e

After horizontal bone loss from periodontaldisease, the PDL-supported root surfacearea can be dramatically reduced potentialabutment teeth need very carefulassessment where significant bone losshas occurred.


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In general, successful fixed prostheses canbe fabricated

on teeth with severely reduced periodontalsupport, provided the periodontal tissues

have been returned to excellent health,and long-term maintenance

has been ensured.


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SEQUENCE OF TREATMENT

TREATMENT OF SYMPTOMSDiscomfort can be due to one or more of the

following: a fractured tooth or teeth, acute

pulpitis, acute exacerbation of a chronic pulpitis,dental abscess, an acute pericoronitis orgingivitis, and myofascial pain dysfunction.


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STABILIZATION OF DETERIORATINGCONDITIONS

The second phase of treatment involves stabilizingconditions such as dental caries or periodontaldisease by removing the etiologic factors,increasing the patient's resistance, or doingboth.


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DEFINITIVE THERAPYWhen the stabilization phase has been completed,

successful elective long-term treatment aimed at

promoting dental health, restoring function, andimproving appearance can begin.


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Usually oral surgical procedures arescheduled first, followed by periodontics,endodontics, orthodontics, fixedprosthodontics, and finally, removableprosthodontics.


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FOLLOW-UP A specific program of follow-up care and regular

recall is an essential part of the treatment plan.

The aim is to monitor dental health, identify thesigns of disease early, and initiate promptcorrective measures as necessary.


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REFERENCES

Rosenstiel, S.F., Land, M.F., and Fujimoto, J.(2006). Contemporary Fixed Prosthodontics. 4 th Ed. Mosby.

Shilingburg, H.T. (2003).Fundamentals of FixedProsthodontics. 3 rd Ed. Quintessence Pub. Co. Jacobs D.J, Steele J. G. and Wassell R. W.

Crowns and extra-coronal restorations. Part 3:Considerations when planning treatment. BDJ.2002; 192(5): 257-67


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Dr. Maan Ibrahim Al-Marzok 2013

A h d f h l


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At the end of the lecture,students should be able to:

1. Discuss the importance of mouth preparation to controloral environment for long term success of crowns andbridges.

2. Describe the steps for case selection and proper referralfor mouth preparation.

3. Discuss the preparation of foundation restorationbiologically and biomechanically for crown and bridge

work.

4.Mouth Preparation

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