L5 RPD Hindawi

Clinical Workflow For Removable Partial Denture¹

DR. AHMAD HENDAWI

DR. SHERYL TEO

Key Clinical Questions²

• Acrylic or Co-Cr?

• Which impression material?

• Is this impression good enough?

• How do I prevent my impression from getting stuck?

• Do I border mould?

• Do I need an MMR?

• Do I need a secondary impression?

• How do I assess the framework?

• Whether a tooth try-in is needed before processing.

• How to identify the first contact when inserting a denture and adjust conservatively.

• The workflow should begin with the patient’s overall condition and treatment needs, rather than with the edentulous classification alone.

Diagnosis and Treatment Planning

Acrylic vs Co-Cr Decision Making³

Acrylic vs Co-Cr?

Examination and Assessment⁴⁵⁶

Diagnose before you design

• “What denture should I make?”
• “What is happening in this mouth?”

Examination

Periodontal, restorative, occlusal, anatomical, functional, patient-related factors

Can This Tooth Contribute⁷⁸

What is the individual and overall *prognosis?

• Periodontal support
• Mobility
• Caries / restorability
• Crown & root anatomy
• Strategic position
• Cleansability

Lecturer — Tooth Contribution

A tooth should not be judged simply as good or bad; its value depends on the planned denture and overall rehabilitation.

• A restorable tooth with a good prognosis may still be extracted if it does not fit the treatment plan.
• A questionable tooth may be retained when it is a terminal abutment or otherwise crucial to the prosthesis.

Mobility as a Clinical Finding⁹

Mobility is a finding, not a prognosis!

Why is it mobile?

• Periodontal disease
• Trauma from occlusion
• Periapical infection
• Traumatic injury
• Pathologic jaw lesion

Is the cause controlled?

Lecturer — Mobility and Material Choice

Mobility itself is not a disease, so its cause should be identified and treated before deciding whether the tooth can contribute.

• When mobility is caused by trauma from occlusion, manage the occlusal trauma first and then assess the tooth’s response.
• A mobile tooth should not automatically be extracted; if mobility improves or does not progress, it may remain suitable for the denture.
• Mobility alone does not determine whether acrylic or cobalt-chromium is selected.

Periodontitis Staging and Grading¹⁰

Periodontitis: stage, grade and current status

• BOP% = 15
• PD ≥ 5 mm
• Tooth loss
• BL/Age = 0.32
• Envir.
• Syst./Gen.

Polygon surface: 16.45448 Periodontal Risk: medium

(Dental chart with rows for Mobility, Implant, Furcation, Bleeding on Probing, Plaque, Gingival Margin, and Probing Depth across teeth 18–28 and 48–38, shown buccal and lingual, with measurements indicated by blue and red squares.)

Periodontitis: stage, grade and current status

Periodontitis: Staging

Staging intends to classify the severity and extent of a patient’s disease based on the measurable amount of destroyed and/or damaged tissue as a result of periodontitis and to assess the specific factors that may attribute to the complexity of long-term case management.

Initial stage should be determined using clinical attachment loss (CAL). If CAL is not available, radiographic bone loss (RBL) should be used. Tooth loss due to periodontitis may modify stage definition. One or more complexity factors may shift the stage to a higher level. See perio.org/2017wwdc for additional information.

		Stage I	Stage II	Stage III	Stage IV
Severity	Interdental CAL (at site of greatest loss)	1 – 2 mm	3 – 4 mm	≥5 mm	≥5 mm
	RBL	Coronal third (<15%)	Coronal third (15% – 33%)	Extending to middle third of root and beyond	Extending to middle third of root and beyond
	Tooth loss (due to periodontitis)	No tooth loss		≤4 teeth	≥5 teeth
Complexity	Local	• Max. probing depth ≤4 mm • Mostly horizontal bone loss	• Max. probing depth ≤5 mm • Mostly horizontal bone loss	In addition to Stage II complexity: • Probing depths ≥6 mm • Vertical bone loss ≥3 mm • Furcation involvement Class II or III • Moderate ridge defects	In addition to Stage III complexity: • Need for complex rehabilitation due to: – Masticatory dysfunction – Secondary occlusal trauma (tooth mobility degree ≥2) – Severe ridge defects – Bite collapse, drifting, flaring – < 20 remaining teeth (10 opposing pairs)
Extent and distribution	Add to stage as descriptor	For each stage, describe extent as: • Localized (<30% of teeth involved); • Generalized; or • Molar/incisor pattern

Periodontitis: Grading

Grading aims to indicate the rate of periodontitis progression, responsiveness to standard therapy, and potential impact on systemic health.

Clinicians should initially assume grade B disease and seek specific evidence to shift to grade A or C.

See perio.org/2017wwdc for additional information.

			Grade A: Slow rate	Grade B: Moderate rate	Grade C: Rapid rate
Primary criteria	Direct evidence of progression	Radiographic bone loss or CAL	No loss over 5 years	<2 mm over 5 years	≥2 mm over 5 years
	Indirect evidence of progression	% bone loss / age	<0.25	0.25 to 1.0	>1.0
		Case phenotype	Heavy biofilm deposits with low levels of destruction	Destruction commensurate with biofilm deposits	Destruction exceeds expectations given biofilm deposits; specific clinical patterns suggestive of periods of rapid progression and/or early onset disease
Grade modificators	Risk factors	Smoking	Non-smoker	<10 cigarettes/day	≥10 cigarettes/day
		Diabetes	Normoglycemic / no diagnosis of diabetes	HbA1c <7.0% in patients with diabetes	HbA1c ≥7.0% in patients with diabetes

Periodontitis: stage, grade and current status

Stage

• Staging intends to classify the severity and extent of a patient’s disease based on the measurable amount of destroyed and/or damaged tissue of periodontitis and to assess the specific factors that may attribute to the complexity of long-term case management.
• Initial stage should be determined using clinical attachment loss (CAL). If CAL is not available, radiographic bone loss (RBL) should be used. Tooth loss due to periodontitis may modify stage definition. One or more complexity factors may shift the stage to a higher level.

Periodontitis Staging Table

Periodontitis	Stage I	Stage II	Stage III	Stage IV
Severity — Interdental CAL (at site of greatest loss)	1 – 2 mm	3 – 4 mm	≥5 mm	≥5 mm
RBL	Coronal third (<15%)	Coronal third (15% – 35%)	Extending to middle third of root and beyond	Extending to middle third bone destruction
Tooth loss (due to periodontitis)	No tooth loss
Complexity — Local	• Max. probing depth <4 mm • Mostly horizontal bone loss	Not applicable (radiographic bone loss <25–30%)	In addition to Stage II: • Vertical bone loss • Class II or III • Complex ridge defects	In addition to Stage III: • Tooth loss (>4 remaining teeth not deployable) • Severe ridge defects • Bite collapse • < 20 remaining (10 opposing)
Extent and distribution	• Localized (<30% of teeth involved); • Generalized; or • Molar/incisor pattern

How severe? How complex? How much destruction?

Grade + Today

• Grading intends to categorize the rate of periodontitis progression, responsiveness to standard therapy, and potential impact on systemic health.
• Initially assume grade B disease and seek specific evidence to shift to grade A or C.

Periodontitis Grading Table

Periodontitis Grading	Grade A: Slow rate	Grade B: Moderate rate	Grade C: Rapid rate
Progression — Rate	≤5-year	≥1 mm over 5 years	≥2 mm over 5 years
% bone loss / age	<0.25	0.25 to 1.0	>1.0
Radiographic changes	Not visible	Visible over 5 years	Significant
Radiographic bone loss	No significant	Age-related	Destruction exceeds expectations given biofilm control; specific clinical patterns suggestive of periods of rapid progression and/or early onset disease
Additional Factors — Smoking	Non-smoker	<10 cigarettes/day	≥10 cigarettes/day
Diabetes	Normoglycemic / no diagnosis of diabetes	HbA1c <7.0% in patients with diabetes	HbA1c ≥7.0% in patients with diabetes

How is it behaving? How fast is progression? Is disease controlled today?

Periodontitis: stage, grade and current status

Periodontitis Staging

Staging intends to classify the severity and extent of a patient’s disease based on the measurable amount of destroyed and/or damaged tissue of periodontitis and to assess the specific factors that may attribute to the complexity of long-term case management.

Initial stage should be determined using clinical attachment loss (CAL). If CAL is not available, radiographic bone loss (RBL) should be used. Tooth loss due to periodontitis may modify stage definition. One or more complexity factors may shift the stage to a higher level. See perio.org/2017wwdc for additional information.

Periodontitis	Stage I	Stage II	Stage III	Stage IV
Severity — Interdental CAL (at site of greatest loss)	1 – 2 mm	3 – 4 mm	≥5 mm	≥5 mm
RBL	Coronal third (<15%)	Coronal third (15% – 33%)	Extending to middle third of root and beyond	Extending to middle third of root and beyond
Tooth loss (due to periodontitis)	Less than 4 teeth	4 teeth	No limit	No limit
Complexity — Local	• ≤4 mm • Mostly horizontal bone loss	• >4 mm • Mostly horizontal bone loss	• Stage II complexity: – Probing depths ≥6 mm – Vertical bone loss ≥3 mm – Furcation involvement Class II or III – Moderate ridge defect	• Stage III complexity: – Masticatory dysfunction, secondary (tooth mobility) – Bite collapse – < 20 remaining (10 opposites)
Extent and distribution	Add to stage as descriptor	For each stage, describe extent as: • Localized (<30% of teeth involved); • Generalized; or • Molar/incisor pattern

Lecturer — Stage and Grade

The stage and grade influence how prominent the acrylic-versus-cobalt-chromium dilemma becomes.

• Stages 1 and 2, particularly with grade A progression, may make cobalt-chromium more likely to be selected.
• Stages 3 and 4, particularly grades B and C, create greater uncertainty.
• Stage 4 carries a higher risk of further tooth loss, raising concern that teeth may need extraction soon after the denture is made.

Periodontitis Grading

		Grade A: Slow rate	Grade B: Moderate rate	Grade C: Rapid rate
Progression	Radiographic bone loss, probing depths, and clinical evidence of rapid progression	No loss over 5 years	<2 mm over 5 years	≥2 mm over 5 years
	Radiographic bone loss (phase of progression)
	Case phenotype	Heavy biofilm deposits with low levels of destruction	Destruction commensurate with biofilm deposits	Destruction exceeds expectations given biofilm deposits; specific clinical patterns suggestive of periods of rapid progression and/or early onset disease
Risk factors — Smoking	Non-smoker	<10 cigarettes/day	≥10 cigarettes/day
Diabetes	Normoglycemic / no diagnosis of diabetes	HbA1c <7.0% in patients with diabetes	HbA1c ≥7.0% in patients with diabetes

Grade A • Grade B • Grade C

Prognosis Charting¹¹

Prognosis chart by tooth, with factor rows for Pros, Perio, Endo, CO2, and TTP marked positive (+) or negative (−) for teeth 18–28 and 48–38.

Charting legend:

Caries	Fissure sealant	Unerupted
Tooth coloured restoration	Tooth wear	Partially erupted
Amalgam restoration	Retained root	Impacted
Full Metal Crown	Porcelain-bonded crown	Crack
P Pontic	PFM Porcelain-fused metal crown	Fracture
Root canal treated	Drifted	Supraerupted

Prognosis classes:

Prognoses	Class	Additional factors	Symbol
Good	A	Anatomic irregularities	*
Fair	B	Iatrogenic compromising factors
Questionable	C
Compromised	D
Non-salvageable	X

CPITN scores: 2, 2, 2, −, 2, −

Lecturer — Integrated Prognosis

Prognosis should be considered as a whole rather than tooth by tooth or condition by condition.

• Integrate periodontal and endodontic prognosis, restorability, occlusal requirements, and patient factors.
• Plan the prosthesis to accommodate the expected likelihood of future extractions or treatment changes.

Comparing Acrylic and Co-Cr Prostheses¹²¹³

Acrylic prosthesis:

• Lightweight
• Poor retention
• Risk of fracture

Co-Cr prosthesis:

• Stronger
• Better retention
• More expensive

Acrylic¹⁴

• Changing dentition
• Questionable prognosis
• Future extraction likely
• Easy to modify / add teeth
• Transitional treatment
• Flexibility

Co-Cr

• Rigid

• Thin

• Less tissue coverage

• Design-controlled support & bracing

• Potentially more cleansable

• …in the right patient

• Changing dentition

• Questionable prognosis

• Future extraction likely

• Easy to modify / add teeth

• Transitional treatment

• Flexibility

• Extensive caries or uncertain restorability of several teeth

• Extremely mobile teeth

• Generally lower cost

• A well-made acrylic denture can be definitive, although it generally has greater tissue coverage than cobalt-chromium

• Rigid

• Thin

• Less tissue coverage

• Design-controlled support & bracing

• Potentially more cleansable

• …in the right patient

• Less flexible when teeth are expected to be extracted or added later

Shared Decision Making With the Patient¹⁵

The patient is part of the design.

Biology + prognosis + maintenance + cost + time + expectations = SHARED DECISION

Lecturer — Previous Prosthesis

The patient’s previous prosthesis should be examined as part of the decision.

• A patient accustomed to a thin cobalt-chromium denture may not tolerate a thicker acrylic prosthesis.
• Determine what worked, what did not work, and how the new design can improve on it.
• Include the patient’s willingness to accept the time and cost involved in cobalt-chromium treatment.

Workflow Overview and Pathway Comparison¹⁶¹⁷

One patient journey. Two pathways.

1	2	3	4	5	6	7	8	9	10	11
Primary impression	Preliminary articulation	Preliminary Try-in	Survey + design	Special Tray	Mouth prep	Definitive impression	Framework	MMR	Tooth try-in	Insert

• Acrylic

1. Primary impression
2. Preliminary articulation
3. Preliminary Try-in
4. Survey + design
5. Special Tray
6. Mouth prep
7. Definitive impression
8. Framework
9. MMR
10. Tooth try-in
11. Insert

• Question marks indicate that a special tray, MMR, or tooth try-in may not be required in every case.

• Acrylic

• Co-Cr

• Definitive impression

• Special Tray?

• Primary impression

• Insert

• Tooth try-in?

• MMR?

• Special Tray + design

• Mouth prep

• Preliminary articulation

• Survey

• Preliminary Try-in

• MMR

• Dintimont impression

• Framework

• Master-cast surveying

• Framework try-in

Acrylic RPD Workflow

1. Primary impression
2. Preliminary articulation
3. Preliminary Try-in
4. Survey + design
5. Special Tray
6. Mouth prep
7. Definitive impression
8. Framework
9. MMR
10. Tooth try-in
11. Insert

Primary Impression¹⁸

Aim: a diagnostic representation of the dentition and edentulous areas

Lecturer — Primary Tray Modification

A stock tray is normally used for the primary impression, but it may need modification to obtain a useful preliminary model.

• The tray may be modified with compound, putty, green stick, or periphery wax.
• If it is short or contacts the ridge, it can be heated, widened, or extended.

Need for a Secondary Impression

The acrylic workflow: 1. Primary impression → 2. Preliminary articulation → 3. Survey + design → 4. Special Tray → 5. Mouth prep → 6. Definitive impression → 7. Framework → 8. Try-in → 9. MMR → 10. Tooth try-in → 11. Insert.

Ask about the edentulous span and what the impression must achieve.

May Not Need¹⁹

• Short bounded saddle
• Single missing tooth

Ask about the edentulous span and what the impression must achieve.

Workflow: Primary impression → Preliminary articulation → Survey + design → Special Tray → Mouth prep → Definitive impression → Framework → Try-in → MMR → Tooth try-in → Insert (steps 1–11).

• Short bounded saddle
• Single missing tooth

Strongly Consider²⁰

• Kennedy I / II free-end saddle
• Long Kennedy IV
• Large tissue-supported Kennedy III

Lecturer — Secondary Impression Criteria

A secondary impression may not be necessary when the case is tooth bounded or tooth supported, the edentulous space is short, and the primary alginate impression is sufficiently accurate.

• A short bounded space replacing two teeth may not require a special tray if the alginate impression is very good.
• A definitive impression should be strongly considered when the prosthesis is tissue supported, the acrylic must extend fully into the vestibule or sulcus, or the primary impression does not adequately capture the anatomy.

Special Tray²¹

Workflow: Primary impression → Preliminary articulation → Survey + design → Mouth prep → Definitive impression → Framework → Preliminary Try-in → MMR → Tooth try-in → Insert (steps 1–11; Special Tray is step 5).

Perforated Tray²²

• Alginate → 3mm spacer

Non-Perforated Tray

• PVS
• Polyether

Both with a 2mm spacer.

Lecturer — Spacer Guidelines

These spacer values are general guidelines rather than absolute rules.

• A little more space may still function, but insufficient space may cause problems.
• The selected impression material should be used according to its instructions because different products may have different setting times and may not mix appropriately.

Workflow overview (steps 1–11, Special Tray is step 5): Primary, Prem. Artic., Prem. Try-in, Survey + design, Special Tray, Mouth prep, Def. Impression, Framework, MMR, Tooth Try-in, Insert.

Key Instruction²³

The laboratory / technician needs to know what comes next

Lecturer — Bite Record Routine

A bite record should still be taken routinely, even when a full base and rim MMR may not be required.

• Take the required impressions, record the bite, assess whether stable contacts are present, and then decide whether a base and rim are required.
• For cases without stable contacts, a diagnostic base and rim may be requested, treating the patient similarly to a complete-denture patient when establishing vertical dimension.

What Must Be Specified on the Prescription

• Material planned
• Tray perforated / non-perforated
• Spacer requirement
• Purpose of impression → removable / fixed

Lecturer — Laboratory Prescription

The prescription should communicate enough information for the technician to understand the clinical intention rather than requiring the technician to guess the material or design.

• Specify the tray arch and whether tissue stops are required.
• State the intended prosthesis, such as an acrylic removable partial denture.
• A laboratory cannot be criticised for producing an unsuitable tray if the prescription did not provide enough information.

Digital Laboratory Request Form (OHCWA Laboratory Request)

• Temp Number: TEMP00000
• First Name: Peter
• Last Name: Parker
• Date Of Birth: 12/09/1954
• Lab Due Date: 09/09/2026
• Clinician: Stan Lee D-1922
• Operator ID: (blank)
• Select Group: DMD3 ✓, SPEC ✓; DMD4, DCD, GDP not selected
• JOB checkboxes: Digital Scan — [ ], Impression — [✓], Photos In Romexis

Material Selection Table

DENT	U	L	CROWN AND BRIDGE	TOOTH	ORTHO
FULL ACRYL			ZIRCONIA		ESSIX RETAINER
PART ACRYL			EMAX		URA
SPECIAL TRAY	☑	☑	PMMA		MED STENT
RELATIONS			ENAMIC		RETAINER
TRY IN			PFM		TRUTANE
PROCESS			GOLD		HAWLEY
CLASPS-(NUM)			RESIN BONDED		TWIN BLOCK
REPAIR			POST AND CORE		BLEACHING TRAY
RELINE			IMPLANT		BIONATOR
SOFTLINER			DIAGNOSTIC WAX UP		SPECIAL TRAY
CoCr			RAD GUIDE
SPLINT			SURGICAL GUIDE

(Visual reference diagrams: dental arch templates + spacer drawings.)

Handwritten Instruction at Bottom of Form

INSTRUCTIONS Dear Lab, Please fabricate Upper and Lower Special tray according to the following:

• Maxillary perforated special tray with 3mm spacer for Alginate impression
• Mandibular non-perforated special tray with 2 mm for PVS impression with tissue stops

1. Primary impression
2. Preliminary articulation
3. Survey + design
4. Mouth prep
5. Definitive impression
6. Framework
7. Preliminary Try-in
8. MMR
9. Tooth try-in
10. Insert
11. Special Tray

Instructions (Brief)²⁴

Dear Lab,

Please make special tray.

Instructions (Detailed)

Dear Lab,

Please fabricate Upper and Lower Special tray according to the following:

• Maxillary perforated special tray with 3mm spacer for Alginate impression
• Mandibular non-perforated special tray with 2 mm for PVS impression with tissue stops

Step	Title	Description
1	SEAT	check: gross extension, seating, interference, sharp edges
2	FUNCTION	cheek/lip manipulation; tongue movements
3	TRIM	adjust areas that displace the tray
4	REASSESS	repeat the same movements

Top timeline (1–11):

1. Primary impression
2. Preliminary articulation
3. Preliminary Try-in
4. Survey + design
5. Special Tray
6. Mouth prep
7. Definitive impression
8. Framework
9. MMR
10. Tooth try-in
11. Insert

Definitive Impression

Border Moulding Decisions

Does every special tray need border moulding?

Border mould when functional base extension matters.

Lecturer — Border Moulding Assessment

Border moulding is not required in every partial denture; it is mainly considered when full extension and tissue support are important.

• Before adding impression material, move the cheeks, lips, and tongue to assess the tray.
• If the tray moves substantially during functional movements, the corresponding border may be overextended.
• The goal is no significant movement during functional movements, rather than absolutely no movement under all hand pressure.

Common Situations

• Kennedy I / II free-end saddle
• Long Kennedy IV
• Large tissue-supported saddle
• Posterior maxillary extension where the denture base extends into functionally relevant soft tissue areas

Impression Material Selection²⁵²⁶²⁷

Which material?

• Polyvinyl Siloxane
• Alginate
• Polyether

Which material?

• Polyvinyl Siloxane

• Alginate

• Polyether

• Common

• Rare

Polyvinyl Siloxane (PVS)

• Heavy
• Medium

Lecturer — Impression Material Selection

At the dental school, PVS, including medium and light body combinations, was commonly used, although different clinicians may prefer different combinations such as heavy and light body.

• Alginate can provide an acceptable definitive impression when the material and technique are appropriate.
• Experienced clinicians may use alginate for final impressions, but the alginate used and the clinician’s familiarity with it influence the result.

Why Light Body?²⁸

Where detail matters:

• Rest seats
• Guide planes
• Prepared tooth surfaces
• Lingual plate contact
• Palatal plate contact

Dental model showing impression technique; injectable dental implant sleeve.

Lecturer — Light Body Placement

Light body is useful for capturing surface detail in areas where a heavier material may drag or fail to record anatomy.

• It may be placed on the teeth, tissues, in the tray, or in selected areas requiring greater surface detail.
• For a straightforward acrylic denture, medium-body material may be sufficient.

Block Out of Undercuts

Spot the Risk

• Black triangles / open embrasures / large interdental spaces
• Gingival recession
• Tipped teeth
• Bridge or pontic undercuts
• Mobile / periodontally compromised teeth

Block Out

• Periphery wax
• Light-cure gingival barrier
• PTFE / Teflon tape
• Oraseal
• Temporary restorative material

Lecturer — Undercut Block-Out

Undercuts should be blocked out when impression material may lock into them, especially with polyether, heavy PVS, or deep interproximal and tooth undercuts.

• Polyether becomes very rigid and should not be used without blocking significant undercuts.
• Removal may otherwise require sectioning the tray or cutting the impression and may risk soft-tissue injury.
• Block-out should prevent locking while still allowing the material to extend into the required area.

Assessing Impression Quality

Did it record what I needed?

Lecturer — Impression Defects

The impression should be assessed before acceptance for defects that affect the planned denture area.

• Check for bubbles, drags, tears, or gaps, as well as the ridge, vestibular anatomy, abutments, rest seats, and guide planes.
• A defect between teeth may be acceptable if no acrylic or denture component will occupy that area.
• A major defect in a retromolar pad or buccal shelf area is not acceptable when those areas are required for support or extension.

Tooth-Supported / Bounded Saddle

• Rest seats / guide planes
• Saddle anatomy
• Path-of-insertion information and relevant tooth surfaces

Free-End / Long Saddle

• Abutment teeth
• Entire denture-bearing area
• Buccal + lingual extension
• Retromolar pad / tuberosity
• Functional peripheral form

Maxillomandibular Records²⁹³⁰

When Do I Need an MMR?³¹

Required / Essential:

• Kennedy I / II free-end saddle
• Long Kennedy IV
• Unstable occlusal stops
• VDO change

Not essential:

• Kennedy III (when hand articulation is possible)

Procedure Timeline³²

1. Primary impression

2. Preliminary articulation

3. Preliminary try-in

4. Survey + design

5. Special tray

6. Mouth prep

7. Definitive impression

8. Framework

9. MMR

10. Tooth try-in

11. Insert

12. Primary impression

13. Preliminary articulation

14. Preliminary try-in

15. Survey + design

16. Special tray

17. Mouth prep

18. Definitive impression

19. Framework

20. MMR

21. Tooth try-in

22. Insert

Do not ask only:

“Can the patient bite together?”

Ask:

“Can the technician articulate these casts predictably?”

1. Primary impression
2. Preliminary articulation
3. Preliminary try-in
4. Survey + design
5. Special tray
6. Mouth prep
7. Definitive impression
8. Framework
9. MMR
10. Tooth try-in
11. Insert

Cast-Rocking Test³³

Practical MMR guide for acrylic RPDs — “cast-rocking test”

Put the models together:

• Are they stable?
• Are they rocking / sliding?

Lecturer — Bite Record Checking

The bite record itself must be checked before it is accepted.

• Look for perforations and bubbles, confirm that the contacts correspond to the patient’s mouth, and remove excess material from interproximal areas.
• A record extending into interproximal areas may prevent the casts from seating properly and create an artificially open articulation.

Can I Scan the Bite?³⁴

More predictable:

• Short bounded saddle
• Stable teeth
• Good access + moisture control
• Reliable occlusal landmarks
• Minimal tissue displacement

More challenging:

• Long edentulous span
• Free-end saddle
• Mobile / displaceable tissues
• Functional border required
• Limited access or difficult tongue/cheek control
• Few stable occlusal landmarks

The scan can look beautiful… but the bite can still be wrong.

Always validate the digital record clinically.

Lecturer — Digital Bite Scanning

Digital bite scanning becomes more difficult with free-end saddles, long edentulous spaces, mandibular scans, saliva, or a lack of posterior contacts.

• Examine the digital occlusion before exporting the record; a contact-only display may show that the scanner has failed to identify contacts present clinically.
• When following a conventional workflow, remain within that workflow rather than moving unnecessarily between digital records and printed models.

Guidelines for Digital Interocclusal Records: Part 1 – Dentate and Partially Dentate Patients

Mar 04, 2026 // 15 min read

Ahmad Hendawi, Sheryl Teo, Adam Hamilton, Aaron Wong

DOI: 10.63580/ITI.FI.45775

Tooth Try-In or Direct Finish

Tooth Try-In Is Preferred³⁵

• Multiple teeth
• Aesthetic zone
• Uncertain tooth position
• Occlusal uncertainty
• Altered VDO
• Clinician/student uncertainty

Direct Finish May Be Reasonable

• Single straightforward tooth
• Good neighbouring references
• Stable occlusion
• Minimal aesthetic risk

Lecturer — Shade Documentation

When direct finishing is selected, a shade tab and a photograph of the shade in the patient’s mouth should be sent to the laboratory.

• The photograph helps the technician verify the shade under the relevant clinical conditions.

Tooth Try-In: What Are You Approving?

• Tooth position
• Aesthetics
• Phonetics
• Occlusion
• VDO (where relevant)
• Patient acceptance

Lecturer — Try-In Assessment

The try-in should also be assessed for the smile line, canine line, midline, tooth size and shape, shade, retention, stability, and patient satisfaction.

• The patient should confirm that the appearance is acceptable before processing.
• Vertical dimension can be checked by comparing natural tooth contact with denture tooth contact using shim stock between the same natural teeth with and without the denture.

Insert

DO NOT JAM IT IN!

Path of Insertion³⁶

• Posterior → anterior?
• Right → left?
• Simultaneous seating?

Look for the First Contact, Then Adjust Conservatively

1. Rigid acrylic interface
2. Clasp

Lecturer — Conservative Insertion Adjustment

Adjustments should be gradual: identify the first contact, remove a small amount of material, reseat the denture, and reassess.

• Avoid large adjustments or prolonged adjustment without reassessing the cause.
• Over-trimming can open embrasures and cause food packing.

Lecturer — Surveyed Crown Risk

For a cracked tooth being considered for a surveyed crown, the patient should be informed that the tooth may fail.

• A crown may brace the tooth, but adding a rest may affect the risk.
• The design should be assessed and approved before treatment.

Co-Cr RPD Workflow

Why Consider Co-Cr

Acrylic vs Co-Cr

Acrylic

• Changing dentition
• Questionable prognosis
• Future extraction likely
• Easy to modify / add teeth
• Transitional treatment
• Flexibility

Co-Cr

• Rigid
• Thin
• Less tissue coverage
• Design-controlled support & bracing
• Potentially more cleansable

…in the right patient

Why Consider Co-Cr³⁷

Workflow Overview³⁸

1. Primary impression
2. Preliminary articulation
3. Preliminary try-in
4. Survey + design
5. Special tray
6. Mouth prep
7. Definitive impression
8. Framework
9. MMR
10. Tooth try-in
11. Insert

Process Comparison: Acrylic vs Co-Cr

Process	Acrylic	Co-Cr
Primary impression	Green	Green
Preliminary articulation	Green	Green
Preliminary try-in	Yellow	Green
Survey + design	Green	Green
Special tray	—	—
Mouth prep	—	Green
Definitive impression	—	—
Framework	—	Green
MMR	—	Green
Tooth try-in	—	—
Insert	—	—

Preliminary Articulation

How Can I Articulate the Diagnostic Casts?³⁹

PVS bite registration

Diagnostic MMR

• Base and occlusal rim fabricated intraorally / on the study model, or requested from the laboratory

Preliminary Try-In

Sometimes you need the teeth before the metal.

Consider Diagnostic Tooth Arrangement When

• Anterior tooth position is uncertain
• Class II / III interarch relationship
• Limited prosthetic space
• Framework must support an unusual tooth position

Establish tooth position first, then design the framework accordingly.

Survey and Design

What Does the Preliminary Survey Tell You?⁴⁰

The survey answers:

• Undercuts

• Path of insertion

• Interferences

• Support and guidance

• Rest locations, retentive and reciprocal clasp positions, indirect retention, and available prosthetic space Survey → Design → Prepare

Surveyed Diagnostic Cast Includes

• Survey line
• Undercut gauge
• Proposed rest
• Guide plane
• Path arrow

Lecturer — Articulated Casts

The survey should be reviewed on articulated casts when occlusion and available space are relevant.

• The articulated casts should remain on an articulator during assessment.
• Two unmounted casts do not provide the same information.

Mouth Preparation

Mouth Preparation Is Design-Driven⁴¹

Every preparation should have a reason.

• Rest seats
• Guide planes
• Enamel recontouring
• Interference reduction where appropriate

Lecturer — Rest Seat Preparation

A rest seat may not require preparation when there is sufficient opposing space and the metal can sit on the tooth without creating an occlusal interference.

• A rounded marginal ridge may provide a favourable situation.
• A deep V-shaped area is more likely to require preparation.

Survey Master Model

Re-Survey the Master Cast⁴²

Did we create what we planned?

Check:

• Path of insertion
• Guide planes
• Useful undercuts
• Rest locations
• Framework design

Lecturer — Master Cast Comparison

The master cast should be compared with the preliminary cast after the definitive impression.

• The casts may not survey identically because they cannot always be positioned at exactly the same angle.
• Comparison helps distinguish surveying differences, insufficient preparation, and changes in the definitive cast.

Framework

Prove the Framework⁴³

Do not add wax yet.

Start on the Master Model — Check

1. Seating — full adaptation
2. Support — rest contact
3. Stability — no rocking
4. Retention — clasp engagement
5. Function — no interference

Poor adaptation vs good adaptation.

If It Does Not Seat, Do Not Force It⁴⁴

Find the interference → possible sources:

• Tooth interference
• Guide-plane discrepancy
• Rest interference
• Connector interference
• Distorted framework
• Incorrect path

Lecturer — Framework Seating Problems

If the framework fits the master model but not the mouth, the problem may relate to the impression or the patient’s teeth rather than the laboratory framework.

• Fit checker or occlusal spray can help identify the area preventing seating.
• Sending the same model back for a remake will not correct an inaccurate impression.
• A substantial discrepancy may require a new impression and new framework.

What Can Be Adjusted?⁴⁵

Possible examples:

• Minor clasp adjustment
• Very limited rest adjustment
• Acrylic component adjustment

Lecturer — Framework Adjustments

Framework adjustments require caution because components may be thin, and excessive adjustment may weaken or fracture the framework.

• Clasp adjustment is not always the solution.
• Add-on components should not be adjusted casually.
• Framework adjustment should involve the supervisor.

Major discrepancy ≠ more grinding → remake framework

Framework With or Without MMR

Framework Fits, What Is Next?⁴⁶

Can we safely save a visit?

Option 1: Send to Lab

Send to lab → Lab adds rim → Patient returns → Record MMR

When to Choose This Option

• Unstable rim
• Major VDO change
• Complex jaw relationship
• Uncertain tooth position
• Inadequate time / skill to make a reliable record

Can we safely save a visit?

Send to lab → Lab adds rim → Patient returns → Record MMR

• A laboratory-made rim is particularly useful when the edentulous space is extensive, the vertical dimension is being increased, or natural teeth do not provide stable contacts

Option 2: Adapt Rim Chairside⁴⁷

Adapt rim chairside → Record MMR today

• Save appointment
• Save lab fee

How to Build the Rim Chairside?⁴⁸

Warm → Adapt → Support → Shape → Re-seat

Lecturer — Chairside Wax Rim

When adapting a wax rim chairside, avoid excess wax beneath the framework and prevent tipping or movement.

• Shape the rim to follow the planned tooth position and curvature of the arch.
• Form the labial contour when anterior tooth position is important.
• The wax rim acts as a blueprint for the tooth arrangement.

Communicate

• Tooth position

• Labial support

• Occlusal plane

• Overjet

• Overbite

• Arch form

• Smile line, canine line, midline, tooth size and shape, tooth shade, and the intended vertical dimension

Tooth Try-In: What Are You Assessing?⁴⁹

Assess:

• Tooth position
• Aesthetics
• Phonetics
• Occlusion
• Retention and stability
• VDO (where relevant)
• Patient acceptance

Co-Cr Insert

Insert⁵⁰

Framework discrepancy? → Stop + re-assess for remake

Assess

1. Seating — full adaptation
2. Support — rest contact
3. Stability — no rocking
4. Retention — clasp engagement
5. Occlusion — no interference
6. Tissues — no impingement
7. Insertion — correct path
8. Removal — patient capable

Adjust acrylic / occlusion as indicated.

Lecturer — Processing Discrepancy

The acrylic may shrink or change during processing, creating a discrepancy even when the framework and tooth try-in were previously satisfactory.

• Assess the acrylic first using pressure-indicating paste or fit checker.
• Confirm framework seating, check occlusion, and adjust conservatively.

• Check the prognosis and suitability of the remaining teeth
• Re-survey the master cast before framework fabrication
• Check indirect retention, prosthetic space, interferences, and occlusal clearance
• Consider whether a new impression is needed if the framework does not fit
• Decide whether a laboratory-made or chairside rim is appropriate
• Confirm tooth position, aesthetics, phonetics, occlusion, vertical dimension, support, stability, and retention

Lecturer — Workflow Planning

These checklists are learning aids for the first several cases, until the workflow becomes familiar.

• Plan from the final treatment objective backwards and understand why each record or impression is being taken.
• Communicate clearly with the laboratory and assess models, impressions, articulations, and frameworks rather than accepting them automatically.
• Consider the patient’s prognosis, expectations, time, and cost to help reduce remakes, errors, and unnecessary adjustments.

Summary and Clinical Checklists

Acrylic RPD — Clinical Stages⁵¹

1. Primary impression
2. Special tray
3. Definitive impression
4. MMR
5. Tooth try-in
6. Insert

Co-Cr RPD — Clinical Stages

1. Primary impression
2. Preliminary articulation
3. Preliminary try-in
4. Survey + design
5. Special tray
6. Mouth prep
7. Definitive impression
8. Framework
9. MMR
10. Tooth try-in
11. Insert

Acrylic RPD — Clinical Checklist⁵²

1. Primary Impression

• Alginate + suitable stock tray
• Accept only if relevant teeth and saddles are captured
• Decide: special tray / secondary impression?
• Lab instructions:
  • Final impression material:
  • Perforations
  • Spacer requirement:
  • Tissue stops

2. Special Tray

• Assess on the model
• Check gross extension, seating, sharp edges and interference
• Trim → smooth → reassess
• Border mould needed

3. Definitive Impression

• Adhesive
• Identify and block undercuts
• Check extension, defects, distortion and safety
• Lab instructions:
  • Please pour impressions
  • Can casts articulate predictably?
  • If not: fabricate hard record base / rim
  • Clasp positions

4. MMR

• Record a repeatable jaw relationship
• Same CD MMR principles
• Lab instructions:
  • Setup teeth on the same hard base
  • Tooth shape:
  • Shade:

5. Try-in

• Essential for multiple teeth, aesthetics or occlusal uncertainty
• Direct finish may suit small bounded saddles
• Assess aesthetics, phonetics, occlusion and VDO where relevant
• Document patient approval
• Lab instructions:
  • Any changes:
  • Please process

6. Insert

• Identify path of insertion: do not force
• If not seated: adjust
  • Rigid acrylic interference
  • Clasp retention
  • Assess extensions and pressure areas
• Patient inserts/removes; hygiene and review arranged

Co-Cr RPD — Clinical Checklist (Part 1 of 2)

1. Primary Impression

• Alginate + suitable stock tray
• Accept only if relevant teeth and saddles are captured
• Decide if diagnostic base and rim is required for preliminary articulation
• Lab instructions:
  • Pour primary impressions
  • Fabricate diagnostic base and rim; then clinically proceed with diagnostic MMR, then ask lab to articulate
  • Articulate models using bite reg if diagnostic base and rim are not needed
  • Preliminary survey

2. Special Tray

• Assess on the model
• Check gross extension, seating, sharp edges and interference
• Trim → smooth → reassess
• Border mould if needed

3. Preliminary Articulation / Preliminary Try-in

• Assess interarch relationship and prosthetic space
• Ask for preliminary tooth setup in complex cases
• Lab instructions:
  • Any changes:
  • Please process

4. Survey + Design

• Survey diagnostic cast: path, undercuts and interferences
• Plan support, bracing, reciprocation and retention
• Design connector, rests, clasps and bases
• Identify required mouth preparations
• Supervisor approval and design documented
• Lab instructions:
  • Fabricate special tray (PVS/iron perforated with 3 mm spacer and tissue stops)

5. Framework Try-in

• Check on master cast
• Assess seating, support, stability and function
• If not seated: do not force — identify why and ask
• Lab instructions:
  • Please pour secondary
  • Fabricate metal frame to the design

6. Syringe / Definitive Impression

• Check gross extension, seating, sharp edges and interference
• Trim → smooth → reassess
• Border mould if needed
• Adhesive
• Verify preparations before:
  • Light body on rests, guide plate-contact areas
  • Check extension, defects
  • Framework still seats and rim is stable
  • Record a repeatable jaw relationship
  • Same CD MMR principles
• Lab instructions:
  • Setup teeth
  • Tooth shape:
  • Shade:
  • Attach full face photos with rim in mouth: smiling and at rest

7. MMR

• Only after verified framework
• Can it be recorded today with a chairside rim?
  • If yes: warm, adapt, support, shape and re-seat
• Framework still seats and rim is stable
• Record a repeatable jaw relationship
• Lab instructions:
  • Same CD MMR principles
  • Setup teeth
  • Tooth shape:
  • Shade:
  • Attach full face photos with rim in mouth: smiling and at rest

8. Insert

• Identify path of insertion: do not force

• If not seated: adjust

  • First interference (PIP, occlusal spray, Fit Checker)

• Assess extensions and pressure areas

• Patient inserts/removes; hygiene and review arranged

• Identify the first contact and adjust conservatively

Closing⁵³

THANK YOU

• AH — Ahmad Hendawi
• ST — Sheryl Teo

Prosthodontics

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Clinical Cases

Case: OPG Presentation for Removable Partial Denture

Question

Scenario: A patient presents to the clinic with missing teeth, and an OPG is shown to the students.

What’s shown: An OPG of a patient with missing teeth.

Consider: Beyond simply identifying the edentulous spaces and missing teeth, what factors must be evaluated to decide between an acrylic or chrome denture?

Answer

Observations:

• Periodontal prognosis (mobility, stage, grade)
• Restorability and remaining tooth structure
• Occlusal anatomical function
• Patient-related factors and previous prosthesis history

Reasoning: The decision for acrylic versus chrome is not based solely on Kennedy classification or missing teeth. The clinician must evaluate the overall condition of the mouth, including whether teeth are useful for the denture design, the cause of mobility, and what the patient previously tolerated, to ensure the new design improves upon the previous one.

Takeaway: Look beyond the edentulous spaces and evaluate the periodontal prognosis, restorability, occlusal function, and previous prosthesis history to guide the decision between acrylic and cobalt chrome.

Case: Erratic Tooth Impeding Denture Design

Question

Scenario: A patient has a super erratic tooth that is getting in the way of the occlusal scheme.

What’s shown: A sound, non-mobile tooth that does not need restoration but is impeding the balanced denture design.

Consider: Should this tooth be kept or extracted?

Answer

Observations:

• The tooth is sound, not mobile, and doesn’t need restoration.
• It is impeding the creation of a balanced denture.

Reasoning: Even if a tooth is restorable and has a good prognosis, if it doesn’t fit the treatment plan or impedes a balanced denture, there is no point in keeping it. The focus should be on whether the tooth is useful for the overall prosthesis design.

Takeaway: A tooth’s usefulness for the overall prosthesis design is more important than just its individual restorability or prognosis.

Case: Bounded Saddle Replacing Two Teeth

Question

Scenario: A patient needs a denture replacing just two teeth in a bounded saddle.

What’s shown: A bounded edentulous space replacing two teeth.

Consider: Is a special tray and secondary impression needed for this case?

Answer

Observations:

• The space is a bounded saddle.
• Only two teeth are being replaced.

Reasoning: For a bounded saddle, there is no need to extend the acrylic flange into the full vestibule for tissue support. If the primary alginate impression is good, it can be used as the final impression without a special tray or secondary impression.

Takeaway: Bounded saddles replacing a few teeth may not require a special tray or secondary impression if the primary impression captures the necessary anatomy.

Case: Rural Patient Driving Four Hours

Question

Scenario: A patient in a rural area has driven four hours to the clinic and wants to minimize chair time and appointments.

What’s shown: A clinical scenario of a patient with limited availability and long travel distance.

Consider: How can the impression workflow be modified to save the patient an extra trip?

Answer

Observations:

• The patient has a long travel distance and limited time.
• A standard multi-step special tray workflow would require multiple visits.

Reasoning: The clinician can customize the primary stock tray impression (e.g., adding putty or border molding directly) to capture the necessary extensions in a single visit, skipping the special tray step to save the patient time and travel.

Takeaway: Patient circumstances, such as travel distance and time constraints, can justify modifying the standard impression workflow to save appointments.

Case: Stuck Polyether Impression

Question

Scenario: A polyether impression gets stuck in the patient’s mouth due to undercuts.

What’s shown: A clinical scenario where a rigid impression material locks into undercuts.

Consider: What is the immediate management when a polyether impression is stuck?

Answer

Observations:

• Polyether is extremely hard when set.
• The impression is locked in undercuts and cannot be removed.

Reasoning: The clinician must section the special tray and cut the impression material intraorally to release the undercuts. This is a risky procedure that can tear soft tissue, emphasizing the need to block out undercuts before taking a polyether impression.

Takeaway: Always block out undercuts before using polyether to prevent the impression from locking and requiring intraoral sectioning.

Case: Assessing Impression Deficiencies

Question

Scenario: A student presents an impression with a drag or deficiency and asks if it is acceptable to proceed.

What’s shown: An impression with a drag in the buccal area versus a deficiency in the retromolar pad area.

Consider: How does the location of an impression deficiency affect the decision to proceed?

Answer

Observations:

• A drag in the buccal area where no denture extension is planned.
• A deficiency in the retromolar pad or buccal shelf area.

Reasoning: A drag in an area not relevant to the denture design (like the buccal vestibule where the denture won’t extend) is acceptable. However, a deficiency in a critical support area like the retromolar pad means the impression failed its purpose and must be retaken.

Takeaway: Evaluate impression deficiencies based on their relevance to the planned denture design and tissue support areas.

Case: Missing 15, 16, 17 and Need for MMR

Question

Scenario: A patient presents missing teeth 15, 16, and 17, with all other teeth present.

What’s shown: A dentition with a unilateral free-end saddle (missing 15, 16, 17).

Consider: Does this patient need a Maxillomandibular Relationship (MMR) record?

Answer

Observations:

• The patient is missing 15, 16, and 17.
• The rest of the dentition is present.

Reasoning: While there are posterior occlusal stops on the other side, free-end saddles (Kennedy Class 1 and 2) can cause models to tilt during articulation. The lab technician needs stable models, so an MMR is recommended to ensure accurate articulation and prevent rocking.

Takeaway: Even with existing occlusal stops, free-end saddles require an MMR to prevent model tilting and ensure accurate articulation.

Case: Modifying the Missing Molar Scenario for MMR

Question

Scenario: The lecturer modifies a previous scenario: instead of missing 15, 16, 17, the patient has a first molar present but is missing the second molar, with stable occlusal stops.

What’s shown: A dentition with a missing second molar but stable posterior occlusion.

Consider: Does this patient need an MMR?

Answer

Observations:

• The patient has stable occlusal stops (e.g., first molars occluding).
• There is no free-end saddle.

Reasoning: With stable occlusal stops and a bounded or tooth-supported situation (like a Kennedy Class 3 with tripod contact), the models can be stabilized without an MMR. The technician can articulate the models predictably using a bite registration.

Takeaway: Stable occlusal stops and the absence of free-end saddles may allow for articulation without a formal MMR, provided there is tripod contact.

Case: Kennedy Class 3 Model and Tripod Contact

Question

Scenario: The lecturer passes around a Kennedy Class 3 model to demonstrate articulation.

What’s shown: A Kennedy Class 3 model with posterior and anterior teeth present.

Consider: How can you determine if an MMR is needed based on model articulation?

Answer

Observations:

• The model has posterior teeth and anterior teeth.
• It forms a tripod contact (two posteriors, one anterior).

Reasoning: If there is tripod contact, the models can be stabilized on the articulator without rocking. Therefore, a bite registration is sufficient, and a full MMR with base and rims is not strictly necessary.

Takeaway: Tripod contact (two posteriors and one anterior) provides sufficient stability for model articulation without needing a full MMR.

Case: Replacing a Single Central Incisor

Question

Scenario: A patient needs a denture replacing only a single central incisor (tooth 11).

What’s shown: A partial denture design replacing one anterior tooth with stable occlusion and good articulation.

Consider: Is a tooth try-in appointment necessary?

Answer

Observations:

• Only one tooth (tooth 11) is being replaced.
• Occlusal contacts are stable, and a bite registration was taken.

Reasoning: If the occlusion is stable, the shade is correctly chosen (preferably with a photo), and the articulation is accurate, a tooth try-in can be skipped, and the case can proceed directly to the final denture.

Takeaway: A tooth try-in may be omitted for simple, single-tooth replacements with stable occlusion and clear aesthetic instructions.

Case: Framework Try-in with Fit Checker

Question

Scenario: A cobalt chrome framework is tried in the patient’s mouth but doesn’t sit fully.

What’s shown: A framework that is not fully seated, assessed using fit checker or occlusal spray.

Consider: How do you identify and manage the interference preventing the framework from seating?

Answer

Observations:

• Fit checker shows the material rubbing off only in one specific area, indicating a premature contact.
• Occlusal spray shows contact only in that localized area.

Reasoning: The localized rub-through indicates an interference. The clinician should make minimal adjustments to that specific area on the framework (or acrylic) and reseat, rather than adjusting the clasps or forcing it in.

Takeaway: Use fit checker or occlusal spray to localize interferences during a framework try-in, and make minimal, targeted adjustments.

Case: First Visit with No Occlusal Stops

Question

Scenario: A patient presents for their first visit with upper and lower alginate impressions, but has no occlusal stops.

What’s shown: A patient with missing teeth and no stable occlusal contacts.

Consider: What is the workflow for establishing the vertical dimension in this scenario?

Answer

Observations:

• The patient has no occlusal stops.
• Primary alginate impressions are taken.

Reasoning: The clinician should request diagnostic base and rims from the lab. The patient is then treated similarly to a complete denture patient to determine the desired vertical dimension and freeway space. Once the diagnostic MMR is taken, the clinician must stick to that vertical dimension throughout the treatment.

Takeaway: When there are no occlusal stops, use diagnostic base and rims to establish and lock in the vertical dimension early in the treatment plan.

Case: RPD with Surveyed Crown

Question

Scenario: A patient needs an acrylic RPD and a surveyed crown on a tooth that requires an increase in vertical dimension.

What’s shown: A treatment plan combining a surveyed crown and a removable partial denture.

Consider: How should the vertical dimension and crown design be managed before preparing the tooth?

Answer

Observations:

• The patient needs an RPD and a surveyed crown.
• The vertical dimension needs to be increased.

Reasoning: A diagnostic MMR must be taken first to decide the new vertical dimension. The crown is then waxed up to the new vertical dimension before preparation. This ensures the tooth is prepared correctly for the final vertical dimension, avoiding excessive reduction or inadequate space for the crown and denture.

Takeaway: Always perform a diagnostic MMR to establish the final vertical dimension before preparing a tooth for a surveyed crown in an RPD case.

Case: Tooth 37 with a Large Crack

Question

Scenario: A student presents a case where tooth 37 has a large crack, and they are considering a survey crown for an RPD.

What’s shown: A cracked tooth (37) being considered as an abutment for a survey crown and RPD.

Consider: Should the cracked tooth be crowned, and what are the risks?

Answer

Observations:

• Tooth 37 has a large crack.
• It is being considered for a survey crown to serve as an abutment.

Reasoning: Crowning the tooth can embrace it and reduce the potential for crack propagation. However, placing an occlusal rest on a cracked tooth increases the risk of failure. The clinician must warn the patient about this risk and obtain informed consent, ensuring the design minimizes lateral forces.

Takeaway: A survey crown can protect a cracked tooth, but placing a rest on it increases the risk of failure; the patient must be warned and informed consent obtained.

Footnotes

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