Clinical Efficacy and Long-term Observation of Fiber Post-and-Core Crown versus Onlay Restoration for Posterior Teeth with Post-endodontic Defects

Summary

This retrospective clinical study compares fiber post-and-core crowns and all-ceramic onlays for restoring posterior teeth after root canal treatment and demonstrates that all-ceramic onlays provide improved periodontal health, masticatory function, and oral health-related quality of life.

Abstract

This retrospective study aimed to compare the clinical efficacy and long-term outcomes of fiber post-and-core crown restoration and all-ceramic onlay restoration for posterior teeth with defects following root canal treatment. A total of 100 patients treated between January 2020 and December 2022 were allocated to two groups (n = 50 each): a fiber post-and-core crown group and an all-ceramic onlay group. Restoration integrity, tooth integrity, marginal adaptation, interproximal contacts, periodontal parameters (periodontal pocket depth, gingival index, and plaque index), masticatory function (bite force and chewing efficiency), and oral health-related quality of life (OHIP-14 scores) were evaluated before treatment and at 3 months and 2 years after restoration. No significant differences were observed between the groups in restoration integrity, tooth integrity, marginal adaptation, or interproximal contacts at either follow-up. However, the all-ceramic onlay group demonstrated significantly lower periodontal pocket depth, gingival index, and plaque index at both follow-up time points. Bite force and chewing efficiency were significantly greater in the onlay group, and OHIP-14 scores indicated better oral health-related quality of life. At the 2-year follow-up, two restoration failures occurred in the fiber post-and-core crown group, whereas no failures were observed in the all-ceramic onlay group. These findings suggest that all-ceramic onlay restorations provide superior clinical outcomes for posterior teeth after root canal treatment, particularly with respect to periodontal health, masticatory function, and patient-reported quality of life, and may represent a promising alternative to conventional fiber post-and-core crown restorations.

Introduction

Root canal treatment is a common procedure for managing pulpitis and apical periodontitis. Its primary objectives are to eliminate inflammation, prevent the spread of infection, and preserve the function and appearance of the affected tooth by removing infected pulp tissue, disinfecting the root canal system, and sealing it with an appropriate filling material¹. Advances in endodontic techniques have improved treatment outcomes, enabling teeth with pulpitis, apical periodontitis, and extensive structural defects to be preserved for extended periods following successful root canal treatment². Posterior teeth, including pr....

Protocol

This retrospective study was conducted in accordance with the Declaration of Helsinki. The study protocol was approved by the Ethics Committee of WuYi County Stomatological Hospital (Approval No. 2025-1) on February 25, 2025. Patients treated between January 2020 and December 2022 were enrolled. Written informed consent was obtained from all participants for study participation and publication of de-identified clinical images. The research tools used in this experiment are listed in the Table of Materials. The study workflow is illustrated in Figure 1.

Results

A total of 100 eligible posterior teeth were included, with 50 teeth in the fiber post-and-core crown group and 50 in the onlay restoration group. All patients completed clinical follow-ups at 3 months and 2 years postoperatively.

Baseline characteristics
No statistically significant differences were observed in baseline demographic or clinical characteristics between the two groups (all P > 0.05; gender, P = 0.841; age, P = 0.462; education level, P = 0.687; body ma.......

Discussion

Dental caries is the leading cause of tooth defects, particularly in posterior teeth, and affects not only tooth morphology but also masticatory function, dentofacial esthetics, and patients' quality of life¹⁶. With advances in oral healthcare and increasing public awareness, both patients and clinicians have placed greater emphasis on preserving natural teeth whenever possible. Complete root canal treatment is essential for retaining teeth affected by pulpal and periapical disease because it .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
35% phosphoric acid etchant	Bisco, USA	E-59110P	Etching of enamel/dentin before bonding
9.6% hydrofluoric acid	Pulpdent, USA	PEG-3	Etching of ceramic restoration surface
Addition silicone impression material kit	President Dental, Switzerland	PRD.01.PGUMP01	Heavy-body and light-body for final impression
Alginate impression material	Kerr, USA	27477DX-2	Preliminary impression for study model
Bausch occlusion paper	Bausch, Germany	BK-288-3	Occlusal adjustment and contact marking
Bite force tester	West China Medical, China	YHL001	Measurement of maximum bite force
Core resin (for post-and-core build-up)	3M, USA	56864-4	Resin core build-up over fiber post
Dental floss	Johnson & Johnson	1993.0107.205	Checking interproximal contacts
Dual-cure resin cement (part of Multilink N kit)	Ivoclar Vivadent, Liechtenstein	V30339-8	Bonding of crowns and onlays
Fiber post drill (for post space preparation)	3M ESPE (RelyX), USA	56864-4	Part of the core resin kit; used for post space drilling
Flowable resin	Dentsply Sirona (SDR), USA	61C130-5	Cavity sealing and base placement
Full-zirconia crown (prefabricated)	Vita Zahnfabrik, Germany	20182170377	Crown restoration for post-and-core group
Gingival retraction cord	Pascal International (KnitTrax), USA	07-585-7	Gingival displacement for impression
Glass fiber post	3M (RelyX Fiber Post), USA	306831603-8	Post-and-core restoration
Hard plaster / Super-hard plaster	Heraeus Kulzer, Germany	OCTA-SUPERROCK	Pouring of study models and working casts
Hiluster Plus polishing cup	Kerr Rotary, Switzerland	278925	Final polishing of restorations
Iodine glycerol	Xinlong, China	4011244-10	Gingival soothing after retraction and bonding
IPS e.max press onlay (lithium disilicate)	Ivoclar Vivadent, Liechtenstein	U01738	Onlay restoration fabricated in lab
Light-curing lamp	3M, USA	76973	Light curing of adhesive resins (wavelength: 440-480 nm)
Multilink N bonding kit	Ivoclar Vivadent, Liechtenstein	V30339-8	Self-adhesive resin cement for definitive bonding
Occlubrush polishing brush	Kerr, USA	2520	Polishing of restorations and margins
Occlusal registration silicone	President Dental, Switzerland	PRD.01.PGUML01-1	Bite registration and occlusal record transfer
Periodontal probe	Hu-Friedy, USA	PCPUNC15	Measurement of periodontal pocket depth
Saline (0.9% sodium chloride)	Baxter, USA	2F7124	Irrigation and rinsing of root canal and operative field
Self-etch adhesive	3M, USA	41925	Bonding agent for post and crown
Silane coupling agent (Monobond N)	Ivoclar Vivadent, Liechtenstein	Monobond N	Surface pretreatment of ceramic for adhesive bonding
Sodium bicarbonate	Sigma-Aldrich, USA	V900182	Neutralization of hydrofluoric acid after etching
SPSS software	IBM, USA	Version 26.0 ; RRID: SCR_002865	Statistical analysis of clinical data
Ultrasonic device	E.M.S. Electro Medical Systems S.A. (Switzerland)	PIEZON® 150	Cleaning of instruments and ultrasonic activation of root canal irrigants
Vita 3D-master shade guide	Vita, Germany	B360	Shade matching before restoration fabrication