CHAPTER 10: INDIRECT TOOTH COLORED RESTORATIONS

indirect tooth-colored restorations

are esthetic dental restorations

such as inlays, onlays, and overlays

used for class I and II cavities where strength, contour, and esthetics are important

use tooth-colored materials like ceramics, resin composites, or hybrid ceramics to mimic the natural appearance of teeth

fabricated outside the patient’s mouth—either in a dental laboratory or using CAD/CAM systems—and then cemented or bonded to the prepared tooth

indications of indirect tooth-colored restorations

replacement of large, compromised restorations

need for better contour development and occlusal form

large defects or wide restorations needing cusp coverage

esthetic importance in posterior teeth (class I & II inlays / onlays)

contraindications of indirect tooth-colored restorations

heavy occlusal forces (e.g., bruxism, clenching)

inability to maintain a dry field (moisture-sensitive bonding)

deep subgingival margins that are difficult to bond, record, or finish

advantages of indirect tooth-colored restorations

variety of materials and techniques

excellent biocompatibility and tissue response

better control of contours and occlusal contacts

superior wear resistance (especially for occlusal restorations)

strengthens weakened tooth structure through adhesive bonding

reduced polymerization shrinkage stress compared to direct composites

allows delegation to laboratory (increased auxiliary support and efficiency)

improved physical properties due to ideal laboratories & industrial fabrication

disadvantages of indirect tooth-colored restorations

technique-sensitive process requiring high operator skill

shorter clinical track record compared to gold or amalgam

difficult try-in and delivery; polishing ceramics is more challenging

can wear opposing teeth/restorations, especially if rough or unpolished

higher cost and longer treatment time (lab fees, multiple appointments)

brittleness of ceramics; risk of fracture during try-in, cementation, or function

low repairability—fractured ceramics often require replacement rather than restoration

ceramic materials

most indirect tooth-colored inlays and onlays are made from this material due to their esthetics, strength, and compatibility with both laboratory and CAD/CAM techniques.

main ceramic types used for onlay/inlay

feldspathic porcelain

leucite-reinforced pressed ceramics

lithium disilicatw

feldspathic porcelain

less common now but still used by some labs.

partially crystalline minerals (feldspar, silica, alumina) in a glass matrix.

fabrication involves hand-layered on refractory dies and fired in a furnace

pros of feldspathic porcelain

excellent esthetics.

low equipment cost.

compatible with traditional lab setups.

cons of feldspathic porcelain

technique-sensitive.

weak; prone to fracture even after bonding.

time-consuming process with multiple firings.

leucite-reinforced pressed ceramics

ex: IPS impress

positive results in clinical trials up to 12 years.

glass-ceramic strengthened with leucite crystals.

fabrication includes lost-wax method followed by pneumatic pressing of ceramic ingots into molds.

pros of leucite-reinforced pressed ceramics

familiar wax-up technique for labs.

aesthetic with minimal staining needed.

good marginal fit and surface hardness.

higher strength than feldspathic porcelain.

cons of leucite-reinforced pressed ceramics

still fragile

requires adhesive bonding.

slightly lower strength than newer ceramics.

lithium disilicate

ex: IPS E-max press & IPS E-max CAD

increasingly favored for its durability and appearance.

high-strength glass-ceramic with lithium disilicate crystals.

suitable for inlays, onlays, crowns, and ultra-thin veneers.

available in both pressed and machinable (CAD/CAM) formats.

pros of lithium disilicate

high strength.

versatile applications.

excellent esthetics & translucency.

cons of lithium disilicate

still relatively new.

lacks long-term clinical data.

CAD/CAM

computer-aided design computer-assisted manufacturing technology

enables the rapid design and fabrication of high-quality ceramic restorations, either chairside or in a dental laboratory.

2 key systems of CAD/CAM

chairside systems

laboratory systems

chairside systems

ex: CEREC 3D, E4D

use optical scanning

no need for physical cast

allow same-visit restorations

laboratory systems

require submission of impressions (elastomeric or digital)

elastomeric or digital impressions

take interocclusal records

workflow of chairside CAD/CAM

tooth preparation: dentist prepares the tooth.

optical impression: a scanning device captures the shape and surrounding structures.

design (CAD): software allows the clinician or auxiliary to design the restoration digitally.

milling (CAM): the restoration is milled from a ceramic or composite block within minutes.

finalization: the restoration is tried in, adjusted, bonded, and polished.

materials used in CAD/CAM

feldspathic ceramics:

• vitablocs mark II, CEREC blocs

• available in various shades and opacities (some layered for natural translucency)

leucite-reinforced ceramics:

• IPS empress CAD, paradigm C

lithium disilicate:

• IPS e.max CAD

—these materials are industrially fabricated, offering superior physical properties.

advantages of CAD/CAM

speed: fabrication completed in a single visit (chairside).

material quality: blocks made under ideal industrial conditions

customization: various shades, opacities, and layering for esthetic results.

improving technology: more accuracy, ease of use, and better performance over time.

proven results: studies report good longevity of CAD/CAM ceramic restorations.

disadvantages of CAD/CAM

high initial cost of the system.

requires special training for the dental team.

unknown long-term performance for some newer materials.

clinical technique when prepping a tooth

anesthetize and isolate (rubber dam preferred)

remove old restorations and caries

eliminate external stains

occlusal thickness: ≥2 mm

rounded internal angles, butt-joint margins

avoid undercuts (block out with RMGI if present)

proximal clearance: ≥0.5 mm

cap cusps if ≥2/3 of cusp undermined

use tapered diamond / carbide burs

create single path of draw

aligned with long axis

mesio-occlusal (MO) onlay preparation for tooth-colored inlay in mx 1st premolar occlusal view

isthmus should at least be 2mm wide to prevent inlay fracture

the axiopulpal line should be rounded to avoid seating errors and to lower stress concentrations

mesio-occluso-distal (MOD) onlay preparation for tooth-colored inlay in the mx 1st premolar proximal view

the axiopulpal should be rounded

gingival margins in enamel are greatly preferred

the pulpal floor should be prepared to a depth of 2mm

the proximal margins should be extended to allow at least 0.5mm clearance of contact with adjacent tooth

provisional restoration

use bis-acryl composite material

avoid eugenol-based (interferes with bonding)

use non-eugenol, zinc phosphate, resin-based temporary cements

specific techniques for CAD/CAM

accommodate scanner / software limits

experienced clinicians can finish in 1 hour

CEREC blocks minor undercuts for preparation

no conventional impression or provisional needed

try-in bonding

fragile ceramics

moisture-sensitive bonding

resin cements required

use rubber dam

remove all provisional cement/debris

check proximal contacts with floss, articulating paper

adjust with abrasive disks/points and polish before bonding

verify internal and marginal fit

remake if significant interference

remove excess and finish with fine diamonds/carbide burs

clinical technique for bonding

etched the internal surface treatment of ceramic surface with hydrofluoric acid for increased micromechanical retention

apply silane coupling agent to improve chemical bonding with resin cement

etched enamel and dentin with phosphoric acid

selective enamel etching is recommended to avoid decreased dentin bond strength for self-etch adhesives

apply appropriate adhesive system system to internal surfaces of the restoration

use dual-cure resin cement for seat restoration

use composite instruments to remove excess cement; adhesive system

perform multiple-direction light curing, follow manufacturer guidelines bc ceramic thickness may reduce light penetration

clinical technique for finishing and polishing

remove rubber dam and check resin cement setting

use medium/fine-grit diamond burs for excess cement removal

interproximal removal with #12 blade, abrasive strips, or slender burs

use 30-fluted carbide burs for smooth finish

abrasive strips with care to protect gingiva / root

adjust contours with fine-grit diamonds and smooth with carbide burs

use rubber abrasive points and cups for abrasive points and cups

final polish with diamond polishing paste and bristle brush

remove rubber dam, verify marginal integrity, and adjust occlusion

adjust if needed with fine-grit diamonds and polishers, adjust opposing cusp to prevent trauma if needed,

sequence 1

medium-grit to fine-grit diamond rotary instrument

sequence 2

30-fluted carbide burs

sequence 3

sequence of rubber, abrasive-impregnated porcelain polishing points

sequence 4

diamond polishing paste

clinical technique for CAD/CAM inlays & onlays

adjustments are required during try-in, especially for finishing and polishing

early CEREC systems — milled flat occlusal surfaces lacking detail

modern CAD/CAM systems — incorporate detailed occlusal anatomy and can account for opposing occlusion.

systems can extrapolate contours from tooth structure or scanned wax bite

adjacent teeth (marginal ridges, cusp heights) used as design references

preoperative contours can be replicated if clinically acceptable

medium- or fine-grit diamond burs used for contouring

final finishing and polishing follow standard instrumentation techniques

bulk fracture

causes:

• inadequate restoration thickness

• poor prep or occlusal interferences

• inappropriate case selection (e.g., bruxers, clenchers)

solution:

• replacement of the restoration is usually necessary

repair of ceramic inlays & onlays

evaluate repair or replacement options

identify root cause of damage

use mechanical roughening with aluminum oxide or coarse diamond bur but is less effective

apply 5–10% hydrofluoric acid (HF) gel for ~2 minutes to create microdefects for bonding

use silane coupling agent for chemical bonding

apply resin adhesive and light-cure

add composite for proper shade, cure, contour, and polish.