Table 5, Summary of Findings of Included Studies - The Use of Dental Crowns for Endodontically Treated Teeth: A Review of the Clinical Effectiveness, Cost-effectiveness and Guidelines

Main Study Findings	Author’s Conclusions
Fedorowicz et al. 2012,¹⁹ Bahrain (Systematic review)
Type of failure (at three years); one study	Root canal therapy + fiber post + composite core +	Risk ratio (95% CI)	There was insufficient evidence to supporting or refuting the use of full coverage crowns over composite fillings to restore endodontically treated premolars.
Crown (n/N)	Composite restoration (n/N)
Restoration failure	1/53	3/54	0.34 (0.04, 3.16)
Post-realted failure	2/54	1/53	1.96 (0.18, 21.0)
Ng et al. 2010,²⁰ UK (Systematic review)
undefined duration; four studies	Root canal therapy +	Odd ratio (95% CI)	2 to 10 year tooth survival after root canal therapy ranged from 86% to 93%. Crown restoration after root treatment was a significant prognostic factor.
Crown	Direct restoration
Survival probability	Not reported	Not reported	3.9 (3.5, 4.3)
Stavropoulou et al. 2007,²¹ Greece (Systematic review)
Cumulative survival in 10 studies	Root canal therapy +	Difference between groups	Crowns fabricated on endodontically treated teeth provided an acceptable 10-year survival, while direct restorations had satisfactory survival for the short term only.
Crown % (SD)	Direct restorations % (SD)
At 1 year	99% (1)	94% (5)	Not reported
At 2 years	98% (3)	87% (7)
At 3 years	98% (3)	84% (9)
At 5 years	94% (2)	63% (19)
At 10 years	81% (12)	63% (15)
Tickle et al. 2008,²² UK – (Non-randomized study)
Failure rate in five years	Root canal therapy +	Difference between groups	The authors concluded that restoration with a crown may imply a lower risk of post-operative tooth fracture and better coronal seal although this needs further investigation.
Crown	Plastic restoration
Number participants (%)	67 (38.5)	107 (61.5)	Not applicable
Total number of root filling failure (%)	0	16	Not reported
Years with a root filled tooth	274.2	323.3
Failure rate per 100 years with a root filled tooth	0	5.0
Piovesan et al. 2007,²⁷ (Non-randomized study)
Time to failure in a 97-month follow-up period	Root canal therapy + fiber post + composite core +	Difference between groups	The authors concluded that the type of final restoration (resin composite, all-ceramic, and ceramic-fused-to-metal) did not affect the tooth survival. But they admitted that longer-term results are uncertain.
Crown Months (n/N; %)	Composite restoration Months (n/N; %)
Anterior teeth	16, 37, and 43 months (3/20; 15%)	15 months (1/16; 6.3%)	Not reported
Posterior teeth	5 and 63 months (2/48; 14.3%)	No failures (0/26)
Salehrabi et al. 2004,²³ USA – (Non-randomized study)
Number of extracted teeth during the eight year follow up	Root canal therapy +	Difference between groups	The authors did not provide conclusions related to the comparison of interest (crown versus no crown restoration). Reviewer’s note: The authors reported the distribution of extracted teeth in relation to coronal coverage, and the results showed higher percentage of non-crowned teeth being extracted compared to crowned teeth. However, these percentages are misleading because they did not account for the total number of teeth (i.e., the non-extracted teeth).
Crown (with or without post) Number of teeth (%)	Direct restoration Number of teeth (%)
Anterior teeth	1344 (17.0%)	6565 (83%)	Not reported
Premolar teeth	1560 (14.9%)	8879 (85.1%)
Molar teeth	3372 (14.3)	20253 (85.7%)

Cheung et al. 2003,²⁴ (Non-randomized study)
Mean survival time in 10–20 years period	Root canal therapy +	P-value for survival difference (difference was not reported)	The authors concluded that The absence of a preoperative radiolucent lesion and the provision of a crown restoration after treatment were associated with a better tooth survival. They also concluded that anterior teeth and mandibular premolars had higher survival than other teeth.
Crown Months (95% CI); number of teeth	Direct restoration Months (95% CI); number of teeht
Full gold crowns	130 (110, 150); N = 78	95 (80, 109); N = 197	0.001
Ceramic-metal crowns;	150 (138, 163); N = 199	0.000
Partial veneer crowns	148 (119, 178); N = 41	0.003

Main Study Findings

Author’s Conclusions

Fedorowicz et al. 2012,¹⁹ Bahrain (Systematic review)

Type of failure (at three years); one study

Root canal therapy + fiber post + composite core +

Risk ratio
(95% CI)

There was insufficient evidence to supporting or refuting the use of full coverage crowns over composite fillings to restore endodontically treated premolars.

Crown (n/N)

Composite restoration (n/N)

Restoration failure

1/53

3/54

0.34 (0.04, 3.16)

Post-realted failure

2/54

1/53

1.96 (0.18, 21.0)

Ng et al. 2010,²⁰ UK (Systematic review)

undefined duration; four studies

Root canal therapy +

Odd ratio
(95% CI)

2 to 10 year tooth survival after root canal therapy ranged from 86% to 93%. Crown restoration after root treatment was a significant prognostic factor.

Crown

Direct restoration

Survival probability

Not reported

3.9 (3.5, 4.3)

Stavropoulou et al. 2007,²¹ Greece (Systematic review)

Cumulative survival in 10 studies

Root canal therapy +

Difference between groups

Crowns fabricated on endodontically treated teeth provided an acceptable 10-year survival, while direct restorations had satisfactory survival for the short term only.

Crown
% (SD)

Direct restorations
% (SD)

At 1 year

99% (1)

94% (5)

Not reported

At 2 years

98% (3)

87% (7)

At 3 years

98% (3)

84% (9)

At 5 years

94% (2)

63% (19)

At 10 years

81% (12)

63% (15)

Tickle et al. 2008,²² UK – (Non-randomized study)

Failure rate in five years

Root canal therapy +

Difference between groups

The authors concluded that restoration with a crown may imply a lower risk of post-operative tooth fracture and better coronal seal although this needs further investigation.

Crown

Plastic restoration

Number participants (%)

67 (38.5)

107 (61.5)

Not applicable

Total number of root filling failure (%)

Not reported

Years with a root filled tooth

274.2

323.3

Failure rate per 100 years with a root filled tooth

5.0

Piovesan et al. 2007,²⁷ (Non-randomized study)

Time to failure in a 97-month follow-up period

Root canal therapy + fiber post + composite core +

Difference between groups

The authors concluded that the type of final restoration (resin composite, all-ceramic,
and
ceramic-fused-to-metal) did not affect the tooth survival. But they admitted that longer-term results are uncertain.

Crown
Months (n/N; %)

Composite restoration
Months (n/N; %)

Anterior teeth

16, 37, and 43 months (3/20; 15%)

15 months (1/16; 6.3%)

Not reported

Posterior teeth

5 and 63 months (2/48; 14.3%)

No failures (0/26)

Salehrabi et al. 2004,²³ USA – (Non-randomized study)

Number of extracted teeth during the eight year follow up

Root canal therapy +

Difference between groups

The authors did not provide conclusions related to the comparison of interest (crown versus no crown restoration).

Reviewer’s note:
The authors reported the distribution of extracted teeth in relation to coronal coverage, and the results showed higher percentage of non-crowned teeth being extracted compared to crowned teeth. However, these percentages are misleading because they did not account for the total number of teeth (i.e., the non-extracted teeth).

Crown (with or without post)

Number of teeth (%)

Direct restoration

Number of teeth (%)

Anterior teeth

1344 (17.0%)

6565 (83%)

Not reported

Premolar teeth

1560 (14.9%)

8879 (85.1%)

Molar teeth

3372 (14.3)

20253 (85.7%)

Cheung et al. 2003,²⁴ (Non-randomized study)

Mean survival time in 10–20 years period

Root canal therapy +

P-value for survival difference (difference was not reported)

The authors concluded that The absence of a preoperative radiolucent lesion and the provision of a crown restoration after treatment were associated with a better tooth survival. They also concluded that anterior teeth and mandibular premolars had higher survival than other teeth.

Crown
Months (95% CI); number of teeth

Direct restoration
Months (95% CI); number of teeht

Full gold crowns

130 (110, 150); N = 78

95 (80, 109); N = 197

0.001

Ceramic-metal crowns;

150 (138, 163); N = 199

0.000

Partial veneer crowns

148 (119, 178); N = 41

0.003

From: APPENDIX 4, MAIN STUDY FINDINGS AND AUTHOR’S CONCLUSIONS

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Table 5Summary of Findings of Included Studies

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