This document discusses indirect inlay restorations. It begins with an introduction that defines indirect restorations and provides examples. The document then discusses factors that influence preparation design such as the selected material and fabrication method. It also discusses geometrical considerations for preparation design. The document reviews traditional restorative materials like cast gold and composites as well as modern ceramic materials and fabrication methods. It discusses cementation techniques and the importance of adhesive cementation. In summary, the document provides an overview of indirect inlay restoration techniques and materials.

1. Indirect Inlay Restoration
Ammar G. Salem 2nd year KMBS candidate/Erbil centre
Supervision: Dr. Raid Fahim

2. Introduction
 To which Family does it belong to ? And how to differentaite it from other
members ?
 History of indirect inlay and materials development ?
 Definition ?

3. Indirect Restorations
Full coverage Partial coverage
Inlay Onlay overlay
Felden A, Schmalz G, Federlin M, Hiller KA. 1998.
Retrospective clinical investigation and survival
analysis on ceramic inlays and partial ceramic
crowns: results up to 7 years. Clin Oral Investig.
2(4):161–167.
Fuzzi M, Rappelli G. 1998. Survival rate of
ceramic inlays. J Dent. 26(7):623–626.
Schulz P, Johansson A, Arvidson K. 2003. A
retrospective study of Mirage ceramic inlays over up
to 9 years. Int. J Prosthodont. 16(5):510–514.

4. Early inlay restoration material goes back to the use of amalgam with its technqiue forgiveness and
tolerance to saliva and sulcular fluid contamination condition.
Its condensability make producing contact more readily achievable.
Good longevity and low cost made its use surpase other materials in the past century.
Cast gold was considered the gold standard of restorative dentistry due to its inertness and superior physical
properties.
Esthetic demand led to the shift from amalgam and gold to the utilization of ceramic and processed
composite around the mid-to-late 1980s.

5. To inlay or not to inlay
Class I restoration
Class II restoration
(MO,DO, MOD)
Large defect or repeated
failure in direct
restorations
Inability to maintain dry
field
Heavy occlusal forces
(bruxism and clenching)
Deep subgingival margin
Poor oral hygiene

6. Contemporary Esthetic Dentistry

7. Cavity design: between
conventionality and modifications
 Classical design and modern modifications in relation to development in
adhesive dentistry and aspect of geometrical analysis

8. Factors affecting preparation design
Material
selection
Fabrication
method
Adhesive
features
Retention form is not as critical to ceramic as to cast gold
Bevels are contraindicated due to fracture and chipping failures (cavosurface angle 90 degree is preferred)
Smooth flowing margins to facilitate fabrication
Rounded internal angles and butt-joint cavosurface margins to facilitate lab work
Enamel margins vs. dentin end margin

9. Preparation guidelines
External form Internal form
90 degree cavosurface margin Cavity depth 1.5-2.0mm
Smooth margins
Isthmus 1/3rd or less than
inter-cuspal width
Rounded internal angles
Avoid undercuts Cervico-occlusal wall
convergence (10-12) degree
Box wall diverge to occlusal
plane 10 or more degree
Width of gingival floor in
proximal box 1-1.5mm
Width of interproximal box
buccolingually correspond to
intercuspal distance

11. Geometrical considerations
Peaks, sharp edges, small radii regions, or steps and heels and regions with point contact or linear force produces
higher stresses and should be avoided
Avoiding tensile forces and favoring compressive forces design
Minimizing notch stress (increasing surface bearing area)
Arnetzl GV, Arnetzl G
Design of preparatio
for all-ceramic inlay
materials.
International Journal
of Computerized
Dentistry. 2006
Oct;9(4):289-298.

12. Geometrical considerations
Using simplicity in design
Avoid sudden change in cross section
Avoid thin wall sections
Arnetzl GV, Arnetzl G. Design of preparations for all-ceramic inlay materials. International Journal
of Computerized Dentistry. 2006 Oct;9(4):289-298.

13. Geometrical considerations
Hemispherical rather traditional box preparation of the cavity
This increased fracture resistance to 30% and increased surface area for adhesive bonding
Arnetzl GV,
Arnetzl G.
Design of
preparations
for all-ceramic
inlay materials.
International
Journal of
Computerized
Dentistry. 2006
Oct;9(4):289-
298.

14. Restorative materials and fabrication
method: classical and modern perspectives
 explaining the classical materials used for inlay and modern
developments in the field.
 Discussion of drawback and benefits of each material.
 Discussion of clinical need and materials use with respect to each
situation.

15. Cast Gold
an inert material that doesn’t undergo corrosion
Excellent survival rate and advisable for high stress clinical situations (2nd molar,
bruxism)
Require mechanical tooth preparation which lead to loss of sound tooth structure
Unaesthetic and discontinued or rarely used after the further enhancement in ceramic materials
Donovan T, Simonsen RJ, Guertin G, Tucker RV. Retrospective clinical evaluation of 1,314 cast gold
restorations in service from 1 to 52 years. J Esthet Restor Dent 2004;16:194-204.

16. Composite Resin
Indirect resin composite differ by extraoral curing method by heat, pressure and light which improve its physical and
mechanical features
Kildal KK, Ruyter IE. how different curing methods affect the degree of conversion of resin-based inlay/onlay
materials. Acta odontologica Scandinavica. 1994;52(5):315-22.
Peutzfeldt A, Asmussen E. The effect of postcuring on quantity of remaining double bonds, mechanical
properties, and in vitro wear of two resin composites. Journal of dentistry. 2000;28(6):447-52.
Aesthetic variation with multiple shades and translucencies (layering technique)
Repairability which facilitate modifying reparable chipping
Lower cost than ceramic and gold and ease of fabrication
Minimal wear on occluding enamel comparing to ceramic
Inferior longevity compared to
ceramic
Color changing with time Microleakage and secondary caries
Grivas E, Roudsari RV, Satterthwaite JD. Composite inlays: a systematic review. The European Journal
of Prosthodontics and Restorative Dentistry. 2014 Sep;22(3):117-124.

18. Ceramic material
High compressive strenght
Excellent esthetics
Minimal invasive preparation
Protection of remained dental structure
High cost Brittleness Technique sensitive

20. Ceramic manufacture
Chair-side CAD/CAM in-office Lab-side ceramic
Firing porcelain on a
foil or refractory die
Pressed glass ceramic
with lost-wax
technique
Slip cast; glass
infiltrated
Milling from
prefabricated
ceramic blocks
feldspathic
Leucite-reinforced,
lithium disilicate
Lithium disilicate,
leucite reinforced
Aluminous
core
Hopp CD, Land MF.
Considerations for ceramic
inlays in posterior teeth: a
review. Clin Cosmet Investig
Dent. 2013 Apr 18;5:21-32.
doi: 10.2147/CCIDE.S42016.
PMID: 23750101; PMCID:
Limited due to inherent
weakness
Less and defect to conventional
ceramic with improved strength as
3-4 times the traditional core
leucite and lithium are
used for inlays. It
provide excellent
marginal adaptation

21. Addi A, Hedayati-Khams A, Poya A, Sjögren G. Interface gap size of manually and CAD/CAM-manufactured
ceramic inlays/onlays in vitro. J Dent. 2002;30(1):53–58.
The initial marginal adaptation through using CAD/CAM restorations (CEREC) was poor
Improvements led to more predicatable marginal adaptation but still superior marginal adaptation is
exhibited in heat-pressed ceramics.
Hopp CD, Land MF. Considerations for ceramic inlays in posterior teeth: a review. Clin Cosmet Investig
Dent. 2013 Apr 18;5:21-32. doi: 10.2147/CCIDE.S42016. PMID: 23750101; PMCID: PMC3666490
Ceramic fabrication defects and surface cracks initiate as an inherent by-product of the condensation procedure.
Leucite reinforced ceramic raises coefficeint of thermal expansion of the porcelain and result in increased hardness.
Those microcracks develop during cooling phase due to mismatch of coefficient of thermal expansion between
leucite crystals and glassy matrix

22. Methods to strengthen ceramic
thermal
tempering
Chemical
strengthening
Crystalline
reinforcement
Stress-induced
transformation
Hopp CD, Land MF. Considerations for ceramic inlays in posterior teeth: a review. Clin Cosmet Investig
Dent. 2013 Apr 18;5:21-32. doi: 10.2147/CCIDE.S42016. PMID: 23750101; PMCID: PMC3666490

23. cementation
 Brief about types of luting cements.
 Discussion in current adhesive dentistry.
 Clinical application of cementation.

24. Types of luting cements
Traditional acid-based cements : zinc phosphate, glass ionomer  increase risk of inlays fracture
Resin-modified glass ionomer  questionable due to lower cohesive strength than of composite and
fairly short duration of fluoride release
Low-viscosity adhesive resin: dual cure & light cure
Hopp CD, Land MF. Considerations for ceramic inlays in posterior teeth: a review. Clin Cosmet Investig
Dent. 2013 Apr 18;5:21-32. doi: 10.2147/CCIDE.S42016. PMID: 23750101; PMCID: PMC3666490

25. Luting agent selection is a function of the ceramic material chosen to
fabricate the restoration
Silica-based ceramics
(feldspathic, leucite-
reinforced, or lithium
disilicate)
Etched with hydrofluoric acis 
silanated  cementation with
phosphate-modified resin
Lithium disilicate also can be
cemented with traditional luting
without internal surface treatment
Non-silica-based ceramics (dense-
sintered ZrO, or dense-sintered AlO)
Do not benefit from etching, only by
air abrasion
Ceramic inlays are superior to composite resin inlays in terms of light
transmission, which aid achieving higher degree of conversion.
Hopp CD, Land MF. Considerations for ceramic inlays in posterior teeth: a
review. Clin Cosmet Investig Dent. 2013 Apr 18;5:21-32. doi:
10.2147/CCIDE.S42016. PMID: 23750101; PMCID: PMC3666490

26. Polishing Rinse Dried
Etch internal
surface
With
Hydrofluoride
acid
Rinsed and dried
Silane
Applied on
etched surface
30 seconds to 2
minutes
Air dry
Tooth is
etched
Priming Bonding
Isolation of adjacent teeth by teflon tape or soft metal matrix.
Support the inlay while resin is cured.
Any adjusted surface can be polished with diamond polishing paste or rubber points.
Hopp CD, Land MF. Considerations for ceramic inlays in posterior teeth: a review. Clin Cosmet Investig Dent. 2013 Apr
18;5:21-32. doi: 10.2147/CCIDE.S42016. PMID: 23750101; PMCID: PMC3666490

27. Etch and rinse 2-step and 3-step are preferred for the bonding of inlay restoration
It provide more reliable bonding comapred to self-etch and self-adhesive luting agent
It is recommended that fresthly cut dentin surfaces be sealed with a dentin bonding agent immediately
following tooth preparation before taking impresion (immediate dentin sealing) results in a high bond
strength for self etch and total etch adhesives.
Duarte S Jr, de Freitas CR, Saad JR, Sadan A. the effect of immediate dentin sealing on the marginal adaptation
and bond strength of total etch and self etch adhesives. J Prosthet Dent. 2009;102(1):1-9

28. Longevity and success rate
 Studies about success rate regarding indirect inlay restoration.

29. A 10 year
prospective study
on IPS empress
inlays gave 80%-
95% survival
probability
A study on187
ceramic inlays and
onlays over a 10-
year period found
a survival
probability rate of
90.4%
Stoll R, Cappel I,
Jablonski-Momeni A,
Pieper K, Stashniss V.
Survival of inlays and
partial crowns made of
IPS empress after a 10-
year observation period
and in relation to various
treatment parameters.
Oper Dent.
2007;32(6):556–563.
Otto T, De Nisco S. Computer-
aided direct ceramic
restorations: a 10-year
prospective clinical study of
CEREC CAD/CAM inlays and
onlays. Int J Prosthodont.
2002;15(2):122–128.

30. In meta-analysis and systematic review in 2016, searching publish studies between 1983 and 2014.
Through 1289 studies 13 articles were included
According to those, 106 failure out of 4800 restoration.
Chipping and fracture rate was 4%
Endodontic problem was 3%
Chance of failure was 80% less in vital teeth
The study indicates that the survival rate of inlays, onlays, and overlays remains high, irrespective of the
follow-up time (5 y and 10 y) and regardless of the ceramic material, study design, and study setting.
results indicate that fractures remain the most frequent type of failure. The type of tooth does not seem to
affect survival rates, but restorations survived longer on vital teeth.
Morimoto S, Rebello de Sampaio FB, Braga MM, Sesma N, Özcan M. Survival Rate of Resin and Ceramic Inlays,
Onlays, and Overlays: A Systematic Review and Meta-analysis. J Dent Res. 2016 Aug;95(9):985-94. doi:
10.1177/0022034516652848. Epub 2016 Jun 10. PMID: 27287305.

31. In a systemic reivew and analysis of studies in 2018 of published studeis between
1980 and 2017.
Out of 2849 papers, 9 studies were selected for inclusion.
The mean survival rate of inlay was 90.89% while onlays was 93.5% and crowns
95.38%.
Statistical analysis demonstrated the caries is the main biological complication and
root or tooth fracture 11.34% as second after caries.
The 5-year survival rate is very high and exceed 90%.
Vagropoulou GI, Klifopoulou GL, Vlahou SG, Hirayama H, Michalakis K. Complications and survival rates of inlays
and onlays vs complete coverage restorations: A systematic review and analysis of studies. J Oral Rehabil. 2018
Nov;45(11):903-920. doi: 10.1111/joor.12695. Epub 2018 Aug 13. PMID: 30019391.

32. Conclusion
 Although high success rate for inlays, the chipping and fracture of
material remains the major complication.
 Randomized clinical trials are need for future researches to include
multiple variables within the study, as meta- analysis and systemic
reviews failed to record R.C.T studies and heterogenicity was low.
 More advances are needed to dental material specifically ceramic to avoid
its inherent brittleness and complications.