Page 5

Quality Resource Guide –

Chairside CAD/CAM Dentistry

www.metdental.com

Clinical Longevity

here are a significant number of

published studies that report the long-

term clinical performance of CEREC

restorations, in contrast with a general lack

of clinical evidence regarding other chairside

systems. This is primarily due to the fact that

the

CEREC System

has been available since the

early 1990’s and other systems have been more

recently introduced.

A systematic review of 29 clinical studies (2,862

CEREC

ceramic inlays), reported a survival

rate of 97.4% after a period of 4.2 years.

The primary mode of failure was fracture of

the ceramic restoration. Less common failure

modes included fracture of the tooth, wear

of the cement, and postoperative sensitivity.

Another systematic review focused on survival

rates of longer-term clinical trials.

A total of

1,957 single-tooth restorations (98% anterior)

fabricated with CAD/CAM technology were

followed more for than 3 years of functional

service.

The calculated failure rate was 1.75%

per year estimated per 100 restoration years,

based on the survival rate of 91.6% after 5

years. The most common modes of failure

reported were fractures of the restoration or

the tooth.

A number of longer-term studies of CEREC

restorations have also been published.

One

study evaluated the longitudinal performance

of 310

CEREC

onlays.

One operator placed

all restorations with an effort to create all

preparation margins within enamel. After 8

years of follow up, 286 paired onlays were

available for evaluation. The calculated survival

probability was 99.3%. The only two failures

observed in this study were fractures on

maxillary premolars of one patient with occlusal

parafunction.

A study of 2,328 inlays and onlays for 794

patients in a private practice reported 35 failures

over 9 years.

The Kaplan-Meier survival

probability reported was 97.4% at 5 years and

95.5% at 9 years. Another study reported a

Kaplan-Meier survival probability of 90.4% after

10 years for 200

Vitablocks Mark II

restorations

placed in 108 patients in private practice.

a follow-up report of that study, the authors

reported an 88.7% success rate at 17 years.

series of papers from 1991 to 2006 reported the

clinical status of 1,011

CEREC

restorations for

up to 18 years.

23-25

The survival probability was

95% after 5 years, 91.6% after 7 years and 90%

at 10 years. It declined to 84.9% at 16.7 years.

There are a few studies of high strength

chairside CAD/CAM restorations. One reported

the performance of chairside CAD/CAM-

generated

IPS e.max

CAD crowns.

CEREC

system was used to deliver 41 IPS e.max CAD

full-contour crowns (34 patients). One crown

exhibited secondary caries and two crowns

received root canal treatment after two years.

ongoing longitudinal clinical study is evaluating

the clinical performance of 100 IPS e.max CAD

full-contour crowns.

27,28

The first 62 crowns were

delivered with a self-etching bonding agent and

resin cement

(MultiLink Automix [Ivoclar])

an experimental self-adhesive resin cement.

second group of 38 crowns was placed at a later

time using a newer self-etching, self-curing,

cement

(SpeedCem [Ivoclar])

. Each of the full-

contour crowns was placed in a single treatment

appointment with the CEREC system.

There

were no reported failures after two years and no

chipping or cracking were clinically visible. The

percent alpha score (the percentage of examined

restorations with an evaluated characteristic

not significantly different from the baseline

evaluation) were above 95% for color match at

all recall intervals and remained at 100% for

margin adaptation and absence of caries for all

crowns at five years. Four crowns debonded, (3

cemented with the experimental cement [13, 20

and 36 months] and 1 with

MultiLink Automix

[36

months]). One crown cemented with

SpeedCem

presented evidence of crown fracture without

loss of material at 48 months.

In summary, the current state of the evidence on

the clinical performance of CAD/CAM generated

restorations is favorable and indicates that

these restorations perform predictably well.

Adhesive retention of these restorations does

not seem to be a significant issue when careful

luting technique is followed. The incidence

of post-operative sensitivity and/or recurrent

caries is generally an insignificant finding.

Margin adaptation is initially very good, however

there is a tendency for increase in margin

discontinuity and discoloration over time as a

function of the wear of the resin luting cement

in occlusal margins subjected to functional

stress. Irreversible pulpitis is a rare finding and

can generally be attributed to extensive tooth

damage pre-operatively. There is a small risk

of ceramic chipping or fracture over long term

function.

Conclusion

he clinical application of

computerized technology is

one of the most significant

developments

for

restorative

dentistry in recent years.

Laboratory

and clinical evidence confirms the

accuracy of chairside CAD/CAM

restorations.

A significant number of

clinical studies have documented the

clinical success and durability of the

restorations.

Ongoing developments

of computerized systems continue

to expand the clinical applications

to multiple unit restorations and

implants with the introduction of

newer materials specifically designed

for chairside CAD/CAM restorations.