#

Available online at http://www.journalcra.com

INTERNATIONAL JOURNAL
OF CURRENT RESEARCH
International Journal of Current Research
Vol. 9, Issue, 05, pp.50646-50650, May, 2017

ISSN: 0975-833X
RESEARCH ARTICLE

ONLAY PREPARATION TECHNIQUES - CLINICAL PRACTICE GUIDELINES

*Dr. Rubeena. A. Azeem and Dr. Nivedhitha Malli Sureshbabu

Dept. Conservative Dentistry & Endodontics, Saveetha Dental College & University, Chennai, India

ARTICLE INFO ABSTRACT

Article History: Aim: The aim of this clinical practice guideline is to help dental practitioners make decisions
Received 08th February, 2017 regarding appropriate materials and techniques for onlay restorations.
Received in revised form Background: Onlay restorations are an excellent choice for the clinicians to restore structur
structurally
10th March, 2017 compromised posterior teeth. These restorations are bonded directly to the tooth using resin cement
Accepted 29th April, 2017 and can actually increase the strength of a tooth by up to 75%. Many techniques have been suggested
Published online 23rd May, 2017 for the preparation of onlays. Advances in adhesive system and esthetic dental materials such as
composite resins and ceramics have enabled clinicians to use conservative preparations to place
Key words: restorations that also reinforce the remaining tooth structures. In addition, these restorations satisfy
Collection Development of the increasing
increasing patient expectations for a natural or enhanced appearance. More technologically
Libraries, Evaluative, developed systems with fiber - reinforced materials which can be placed in a single - visit provides
Comparative. optimism for the future application of these restorations to the dail
daily clinical practice.

Copyright©2017, Dr. Rubeena. A. Azeem and Dr. Nivedhitha Malli Sureshbabu. Sureshbabu This is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Citation: Dr. Rubeena. A. Azeem and Dr. Nivedhitha Malli Sureshbabu.

Sureshbabu 2017. “Onlay
Onlay preparation techniques - clinical practice guidelines”,
International Journal of Current Research, 9, (05), 50646-50650.
50646

INTRODUCTION necessary (Christensen,, 2012 and Jackson, 1994).Composite

resin onlay restorations have gained popularity since 1980s.
The most commonly placed partial coverage extracoronal The direct composite onlay restoration is formed in the cavity;
restoration would be an onlay where weakened tooth structure after an initial cure, it is remo
removed from the cavity and
can be protected without further extensive tooth removal. A postcured in a heat-and-light
light oven. Improved mechanical and
common indication for an onlay would be a root-filled root physical properties are expected compared with direct lightlight-
posterior tooth where cuspal protection is required. Root canal cured-only
only composite, mainly due to the overall increase in
treatment
atment in molars and premolars is usually the result of caries conversion. Higher stress relaxation and improved ma marginal
and restorative procedures and, as such, these teeth are adaptation is also expected. Shrinkage is limited to a thin
extensively broken down and have weakened cusps. The luting composite resin layer (Wendt, 2012). Indirect
access cavity for a root treatment removes the roof of the pulp laboratory-processed
processed composite onlay restorations also have
chamber, weakening the tooth further, and can leave a limited gained increased popularity over the last decade. Heat,
amount of buccal and lingual tooth tissue which might be pressure, and nitrogen
en atmospheric treatment may be combined
completely removed if prepared for a crown. Preservation of to form a relatively void-free
free well
well-polymerized resin matrix, in
some part of the buccal and lingual tooth helps to retain the an attempt to improve the wear resistance of composite resin.
core and reduces the need to consider der a post, especially in
premolar teeth (Christensen,, 2012 and Jackson, 1994). However, the basic chemistry remains similar to that of the
Bonding materials (including gold) to a tooth, using adhesive direct materials (Swift, 2001) 001).Recently, fiber-reinforced
cements, reduces some of the need for conventional principles composite has been introduced as a dental restorative
of retention. Onlays can be considered when there is no or little composite resin. These single-visit
visit restorations are intended to
intracoronal shape to the preparation and where retention is be used in stress bearing areas since it has the ability to form a
poor. Despite the retention provided by adhesive cement, strong and reinforcing sub-structure.
structure. It can be used as a for the
conventional concepts of tooth preparation for retention should restoration of cavities where inlays and onlays would be
not be ignored and, where possible, should be incorporated indicated (Garoushi, 2013; Garoushi
Garoushi, 2007 and Garoushi,
into the design of the preparation; routine use of adhesive 2008). Long-term
term clinical studies reported no difference in
cements to achieve retention poses problems if retrieval is ever clinical and mechanical properties between direct and ddirect
heat-treated
treated composite resin inlay/onlay restorations (Wassell,
*Corresponding author: Dr. Rubeena. A. Azeem,, 2000).
Dept. Conservative Dentistry & Endodontics, Saveetha Dental
College & University, Chennai, India.
50647 Dr. Rubeena. A. Azeem and Dr. Nivedhitha Malli Sureshbabu, Onlay preparation techniques - Clinical practice guidelines

Overview of various onlay preparation techniques  Make impressions and pour casts of the prepared onlay.
(Fig. 6)
Tooth preparation for the onlay casting  Try the castings on the tooth, adjust the proximal
contacts, evaluate occlusal relationship, and cement the
This technique was given by Dr. Jack G. Seymour in 1987. casting. Use one or two 5/8 inch “metal center” fine
Most posterior teeth can be restored conservatively with a type garnets to finish the exposed margins. After the
II gold by using a minimal number of instruments in an complete set of the cement, review the occlusal surface
organized manner. The instruments needed are No. 1157, No. again (Seymour, 1987).
17OL, and No. 282-010010 carbide burs and a ½ inch fine emery
disk with No. 80-7-14 and No. 10-7-14 14 gingival marginal
trimmers (Seymour, 1987).

 Place depth penetration grooves on the occlusal surface,

develop axial surfaces, and establish the traditional
outline form with a No. 1157 carbide bur. Remove
existing restorations and excavate caries. This may
modify the conventional
ntional outline. (Fig. 1, Fig. 2, Fig. 3)

Fig. 5. Fig. 6

Tooth preparation for esthetic onlay

The principles of cavity preparation for esthetic inlays or

onlays differ from those for gold restorations. For esthetic
Fig. 1. Fig. 2.
2 inlay or onlay restorations, bevels and retention forms are not
needed. Resistance
tance form is generally not necessary but may be
required in very large onlay restorations. Cavity walls are
flared 5 degrees to 15 degrees in total (10 degrees to 12
degrees ideal), and the gingival floor can be prepared with a
butt joint. The internal line angles are rounded, the minimum
isthmus width is 2 mm, and the minimum depth thickness is
1.5 mm (Christensen,, 2012 and Jackson, 1994).

Fig. 3.

 Place the retentive grooves in ¾ crowns and prepare

proximal boxes and occlusal offset for onlays with the
use of a No. 170 L carbide bur. (Fig.4)

Fig. 7.

For onlay restorations, nonworking and working cusps are

covered with at least 1.5 mm and 2 mm of material,
Fig. 4. respectively. If the cusp to be onlayed shows in the patient’s
smile, a more esthetic blended margin is achieved by a further
 Prepare the gingival bevel, buccal and lingual flares, 1- to 2-mm reduction with a 1--mm chamfer (Christensen, 2012
and occlusal offset with the No. 282-010
010 bur. (Fig. 5) and Jackson, 1994). When the occlusal aspect of the cavity is
 Use a fine emery disk on the proximal aspect of the prepared, undercuts should not be eliminated by removing
preparation to finish the flares and slight hollowing that healthy tooth structure, which compromises the conservatism
develop during use of the No. 282-010
010 bur. of this approach. The objective is to establish divergence in the
 Define the proximal box and refine the reverse gingival enamel, then block out all undercuts. This is possible using
bench with hand instruments No. 80-77-014 and 10-7-14. bonded resin or a resin-modified
modified glass ionomer. For cemented
castings it is generally best to overlay a working cusp when the
50648 International Journal of Current Research, Vol. 9, Issue, 05, pp.50646-50650, May, 201
2017

cavosurface margin is more than 50% up the incline of the finishing bur to remove any adhesive that may have flowed
cusp. The cavosurface ace margin can extend up to 75% up the onto these surfaces. After preparation, an impression is
cuspal incline of a nonworking cusp before overlaying of the obtained using an accurate re-pourable
pourable material. This is sent to
cusp is considered. Studies have investigated the use of bonded the laboratory with any additional models, records, or
inlay or onlay restorations for this area, but no clinical information needed to fabricate the restoration. The level of
consensus on when to remove a cuspp has been reached. esthetics achieved with this resto
restoration is directly proportional
Because these restorations reinforce the remaining tooth to the level of communication between the clinician and
structure, the traditional guidelines for overlaying
overlay a cusp as in laboratory technician. Consequently, the color prescription
cast gold onlays have been modified. must contain the occlusal base shade of the restoration, the
gradient of shade from central fossa to cavo
cavosurface margin, the
degree and color of the desired pit and fissure stains, and any
maverick highlights present. The shade is taken before
preparation to avoid the misleading effects produced in a
desiccated tooth. Once this diagnostic information has been
obtained, a direct provisional restoration is placed while the
definitive restorations are fabricated in the laboratory.

A good deal of science is documented in studies over the past

20 years. Significant evidence details the effectiveness of the
enamel bonds in terms of both bond strength and durability.
For esthetic inlays or onlays, evidence supports the
effectiveness of these enamel bonds with regard to tooth
reinforcement. The literature lists tooth reinforcement numbers
Fig. 8. that indicate that when there are significant enamel bond
surfaces, tooth reinforcement is achieved, even up to 70% to
When there is no dentin support directly underneath the cusp 80% of the original strength of the tooth. Clinical evidence
tip, onlay restorations can be done. The palatal or working also supports the longevity of these restorations. A significant
cusp is onlayed, even with dentin support if the margin is number of patients show longevity greate greater than 10 years
within 1 mm of the cusp tip. When the margin is beyond 1 mm (Christensen, 2012 and Jackson
Jackson, 1994). Tooth preparation for
from the cusp tip, the cusp gains dentin support and bond intra- and extra-coronal
coronal restorations follows the similar
strength increases. The horizontal lines depict the direction of concepts as used for indirect restorations. The preparation
the enamel rods. At the cusp tip the enamel rods are almost should avoid undercuts between opposing walls within the
vertical and etching would be on their sides. As the margin cavity. All-ceramic
ceramic restorations depend upon the luting cement
moves away from the cusp tip the ends become etched, which for most of the retention, therefore a slightly overover-tapered
has been shown to increase bond strength (Christensen,
( 2012 cavity is acceptable provided there are no undercuts. However,
and Jackson, 1994). The non-working
working or buccal cusp is not gold restorations gain most of their retention from the cavity
onlayed in this diagram even when the margin is at the cusp shape and are therefore more near parallel preparations can be
tip. If the posterior teeth are discluded in lateral jaw done for these restorations. Inlay and onlay restorations
movements, there are no forces applied to this cusp. It is not preserves tooth tissue to retain the core. If existing cavities
uncommon to find cracks on the pulpal floor under cusps when contain undercuts they can be blocked out with composite or
removing amalgams that have been in place for some time, glass ionomer cements ents to provide the necessary cavity
particularly moderate-sized
sized ones. Whether the teeth exhibit shape.Tapered burs provide the most convenient shape to
pain on chewing (e.g., cracked tooth syndrome) or are prepare onlays and reduce the chance of creating undercuts. If
asymptomatic,, these cusps should be overlayed. A popular an onlay preparation is to be cut, occlusal clearance/ reduction
technique, called immediate dentin sealing (IDS), first will be required consistent with th the material chosen. The
described by Paul and Scharer in 1997, this technique has been marginal configuration (shoulder, chamfer or deep chamfer)
clinically popularized by Dr Pascal Magne. The technique is depends on the material planned (Christensen, 2012 and
based on the logic that the strongest
ngest dentin bond is achieved Jackson, 1994).
when dentin is bonded immediately
diately after being cut and before
becoming contaminated, such as occurs during the provisional Technique for placing tooth-colored
colored onlays
phase. Besides the pulpal protection tion afforded by this
procedure, the patient has more comfort while the th provisional  Anesthetize the tooth if necessary
is in place. Finally, early data show that the ultimate bond of  Clean the tooth prepara
preparation with flour of pumice and
the restoration and the marginal integrity over time are water on a rubber cup
improved.  Selectively place phosphoric acid gel on just the enamel
portions of the margins and perform a standard acid
This technique requires placement of a self-etching
self adhesive etch of the enamel; this is the so
so-called selective etching
followed immediately after curing by a very thin layer of very- technique
low-viscosity
viscosity flowable composite resin. Any undercuts
under are  Seat the onlay with a sel
self-etching resin cement
blocked out simultaneously with the flowable resin. After  Minimally cure the resin cement residue around the
curing, it is necessary to remove the air-inhibited
inhibited layer. This margins and remove it before making the final light
can be done by wiping the surface with a cotton pledget soaked cure
in alcohol.
hol. An alternative technique is to cover the surface with  Floss the contact areas before providing a full light cure
a glycerin product and light curing again. After washing and of the restoration to avoid difficulty in clearing cement
drying, the vertical enamel walls are prepared again with a from the contact areas
50649 Dr. Rubeena. A. Azeem and Dr. Nivedhitha Malli Sureshbabu, Onlay preparation techniques - Clinical practice guidelines

 Finish and polish the margins and correct any high usingg composite finishing and polishing kit. Hence, these
occlusal areas direct restorations can be placed in a single visit and allows for
maximum preservation of tooth structure as well as strengthens
RECENT ADVANCES remaining tooth structure. (Fig. 99-14: Clinical pictures of direct
fiber-reinforced
reinforced composite onlay restorations with 3 year
Direct fiber-reinforced
reinforced composite onlay follow-up – by Dr. Rubeena)

ecently, short fiber reinforced composite resin was introduced CAD-CAM

CAM approach
as a dental restorative composite resin. These direct composite
restorations are now intended to be used in high stress bearing The computer-assisted
assisted design and computer
computer-assisted manufac-
areas especially in molars. The results of the laboratory turing (CAD-CAM)CAM) approach is a valid procedure for
mechanical
cal tests revealed substantial improvements in the load fabricating esthetic inlays or onlays. Many of the ceramic
bearing capacity, the flexural strength and fracture toughness inlays or onlays ordered by dentists today are fabricated in the
of dental composite resin reinforced with short E glass fiber laboratory using milling machines. The two machines available
fillers in comparison with conventional particulate filler in the marketplace today are the CEREC (Sirona Dental
composite resin. The short fiber composite resin has shown Systems, Charlotte, North Carolina) and the E4D (D4D
control of the polymerization shrinkage stress by fiber Technologies, Richardson, Texas). The quality of the
orientation and, thus, marginal micro leakage was reduced restorations that can be fabricated with these milling machines
compared with conventional particulate filler composite resins in the dental office today is as good as that of laboratory
laboratory-
(Garoushi, 2012; Garoushi,f, 2007 andd Garoushi, 2008). 2008) fabricated indirect resin or ceramic restorations with respect to
For direct composite restorations, quadrant isolation is done fit and function. Both approaches depend on the com commitment
using rubber dam sheet. The tooth to be restored is cleaned and skill of the operator. This can be the dentist or a dental
with pumice-water
water slurry in a rubber cup to remove salivary auxiliary who actually does the design and operates the milling
pellicle and any remaining dental plaque. equipment.

Fig. 9 – 14.

Onlay preparation is done using high-speed speed burs. Caries Summary and conclusion
removed with low-speed
speed burs and spoon excavator leaving
discolored but hard dentin at the cavity floor. The preparations Advances in tooth-colored
colored materials and adhesive technology
are done according to the principles of minimally invasive have expanded the scope of restorative dentistry. Onlays are a
dentistry. In cases where the cavity is deep, MTA Plus can be more conservative restorative option than are crowns. The
given (PREVEST Denpro). The prepared tooth is restored results of research are positive regarding onlays’ service
using sectional matrix system (Triodent) that is stabilized using potential. Numerous well-proven,
proven, as well as some new,
anatomical wedges. The bonding procedure begins with the materials such as ceramics and fiber – reinforced composite
application of self-etch adhesive (Gaenial
aenial Bond, GC) to the make the use of tooth-colored
colored onlays a viable procedure.
prepared walls. The application and placement of bonding
agent is done according to manufacturer’s instructions. The REFERENCES
fiber-reinforced
reinforced composite (EverX Posterior, GC) is placed Christensen, G.J. 2012. The case for onlays versus toothtooth-
and light cured according to an incremental technique. All A colored crowns. The Journal of the American Dental
restorations are fully covered with a layer (1-2
(1 mm) of hybrid Association. 2012 Oct 1;143(10):1141
1;143(10):1141–4.
composite resin (Gaenial Posterior, GC). Occlusion is carefully Frankenberger, R., Petschelt, A., Krämer, N. 2000. Leucite-
adjusted using articulating paper. Finishing and polishing reinforced glass ceramic inlays and onlays after six years.
procedures are carried at same visit after occlusal adjustment Part I: Clinical behavior, Oper Dent 25:459-465.
50650 International Journal of Current Research, Vol. 9, Issue, 05, pp.50646-50650, May, 2017

Garoushi, S., Vallittu, P.K., Lassila, L.V.J. 2007. Short glass Otto, T., De Nisco, S. 2002. Computer-aided direct ceramic
fiber reinforced restorative composite resin with semi-inter restorations: 10-year prospective clinical study of CEREC
penetrating polymer network matrix. Dent Mater. 2007 CAD/CAM inlays and onlays, Int J Prosthodont 15:122-
Nov;23(11):1356–62. 128.
Garoushi, S., Vallittu, P.K., Watts, D.C., Lassila, L.V.J. Paul, S.J., Schärer, P. 1997. The dual bonding technique: a
Polymerization shrinkage of experimental short glass fiber- modified method to improve adhesive luting procedures,
reinforced composite with semi-inter penetrating polymer Int J Periodontics Restorative Dent 17:536-545.
network matrix. Dent Mater. 2008 Feb;24(2):211–5. Schulte, A.G., Vocker, A., Reinhardt, R. 2005. Longevity of
Garoushi, S., Mangoush, E., Vallittu, M., & Lassila, L. Short ceramic inlays and onlays luted with a solely light curing
Fiber Reinforced Composite: a New Alternative for Direct composite resin, J Dent 33:433-442.
Onlay Restorations. The Open Dentistry Journal 2013; 7: Seymour, J.G. 1987. A simplified technique for the tooth
181–185. preparation of onlay castings. J Prosthet Dent.,
Jackson, R. 1999. Indirect resin inlay and onlay restorations: a Jan;57(1):9–11.
comprehensive clinical overview, Pract Periodontics Swift, E.J. 2001. Processed Composites. Journal of Esthetic
Aesthet Dent 11(8):891-900. and Restorative Dentistry. Sep 1;13(5):284–95.
Jackson, R.D. 1994. Esthetic inlays and onlays. Curr Opin Van Dijken, J.W.V. 2000. Direct resin composite inlays or
Cosmet Dent. 30–9. onlays: an 11 year follow-up, J Dent 28(5):299-306.
Kramer, N., Frankenberger, R. 2005. Clinical performance of Wassell, R.W., Walls, A.W., McCabe, J.F. 2000. Direct
bonded leucite-reinforced glass ceramic inlays and onlays composite inlays versus conventional composite
after eight years, Dent Mater 21(3):262-271. restorations: 5-year follow-up. J Dent., 28:375-82.
Kramer, N., Taschner, M., Lohbauer, U., et al. 2008. Totally Wendt, S.L., Leinfelder, K.F. 1992. Clinical evaluation of a
bonded Ceramic inlays and onlays after eight years, J heat-treated resin composite inlay: 3-year results. Am J
Adhes Dent. 10:307-314. Dent. Oct;5(5):258–62.
Lehner, C., Studer, S., Brodbeck, U., Scharer, P. 1998. Six-
year clinical results of leucite-reinforced glass ceramic
inlays and onlays, Acta Medica Dentistry Switzerland
3:137-146, 1998.

*******