Mastering Crown and Bridge Dentistry: A Deep Dive with Dr. Faraj Edher and the BC Dental Study Club

The world of dentistry is constantly evolving, and staying at the forefront of clinical excellence requires continuous learning and practical application. We recently had the privilege of attending an exceptionally comprehensive "Crown and Bridge" workshop hosted by the BC Dental Study Club, led by the esteemed prosthodontist Dr. Faraj Edher. This two-day intensive course was a testament to their dedication, offering an unparalleled deep dive into the nitty-gritty details of crown and bridge procedures, backed by robust evidence and real-world clinical insights.

Dr. Edher, a prosthodontist and the founder of the BC Dental Study Club, shared his extensive knowledge and passion for education, emphasizing a collaborative learning environment where clinicians could openly discuss practical challenges and innovative solutions. The course, meticulously designed, covered everything from fundamental preparation principles to advanced material science and digital workflows, aiming to enhance predictability and efficiency in daily practice.

A Comprehensive Approach to Crown and Bridge: Key Takeaways

The workshop's structure allowed for a thorough exploration of each phase of crown and bridge dentistry, providing valuable insights and practical tips.

1. Diagnosis and Treatment Planning: A Patient-Centric Philosophy

Dr. Edher underscored that effective diagnosis begins with understanding the patient's chief concerns and then assessing the clinical situation, including existing restorations, occlusal scheme, and underlying tooth structure. The goal is to provide the best possible outcome while preserving as much healthy tooth structure as possible.

• Crowns, Veneers, and Partial Coverage: The course highlighted that the choice between these restorations should not be based on rigid definitions but rather on the goal of the restoration (aesthetic/functional), the underlying tooth structure after old restorations are removed, and the predictability of bonding. Dr. Edher advocated for educating patients on these nuances, explaining that the process, material, long-term prognosis, and even cost are often similar across these indirect restorations in his practice, allowing the clinician to make the best decision during preparation.

  
  

• Transparent Communication: A crucial aspect was the emphasis on transparent patient communication regarding risks, such as the potential need for a root canal post-crown, regardless of the restoration type. Dr. Edher believes in providing patients with all options, including the decision to decline treatment if it goes against the clinician's philosophical, moral, or ethical comfort.

  
  

• Bridge Indications and Anti's Law: When considering bridges, the discussion moved beyond simply replacing missing teeth. It involved a thorough comparison with alternatives like implants and removable appliances, weighing factors such as time, cost, surgical involvement, and long-term independence of teeth. Anti's Law, which states that the root surface area of abutment teeth should equal or exceed that of the replaced teeth, was presented as a theory rather than a rigid law, emphasizing the need for clinical judgment based on occlusion, patient habits, and available span.

  
  

• Underutilized Gem: Resin Bonded Bridges (Maryland Bridges): Dr. Edher highlighted the often-underestimated value of resin-bonded bridges as a minimally invasive definitive solution for specific indications, primarily mandibular incisors and maxillary lateral incisors. Their historical poor reputation was attributed to older materials (metal wings) and less predictable bonding techniques. Modern single-wing resin bonded bridges boast success rates comparable to traditional bridges and implants (around 91% at 10 years and 84% at 15 years) when proper case selection (out of occlusion in MIP and excursive movements) and meticulous bonding protocols are followed.

  
  

2. Crown Preparation: Precision and Modern Principles

The session thoroughly revisited foundational principles of tooth preparation while critically evaluating their relevance in modern dentistry.

• Retention and Resistance Form: While traditional recommendations like 10-20 degrees of convergence and specific clinical crown heights (3mm for anteriors/premolars, 4mm for molars) are still relevant if luting a restoration, they become irrelevant if bonding is the primary retention mechanism. Resistance form, which prevents dislodgement from lateral forces, is largely obsolete with today's materials and precise design capabilities. Dr. Edher emphasized that removing more tooth structure solely for resistance form is unnecessary given modern bonding advancements.

  
  

• Finish Lines: Current evidence, including a 2019 systematic review and meta-analysis, strongly suggests that chamfer finish lines are superior to shoulder finish lines for ceramic crowns, offering better internal adaptation due to compatibility with milling technology. Dr. Edher now exclusively uses shamfer margins for almost all his crowns.

  
  

• Stump Shade Management: For discolored stumps, effective masking requires intentional preparation. This involves increasing incisal reduction (e.g., 2mm instead of 1mm) and doubling axial wall reduction (e.g., 2mm instead of 1mm) to provide labs with enough space for opaque materials. Zirconia is often the more aesthetic material for masking discoloration due to its lower translucency.

  
  

• Smooth Preparation Surfaces: Contrary to some beliefs, rough preparation surfaces do not increase retentionand can lead to less well-adapted internal surfaces of restorations. Polishing crown preparations with fine-grit diamonds at low RPMs ensures better internal adaptation and fit.

  
  

• Mockup-Driven Guided Preparation: A cornerstone of Dr. Edher's technique is 100% mockup-driven preparation. Whether it's an existing tooth, existing crown, or added composite, the mockup establishes the baseline for the final restoration's desired position. This guided approach ensures precise and conservative reduction, particularly for depth cuts and axial walls, preventing over-preparation.

  
  

• Ferrule: The Unsung Hero: The true purpose of a ferrule is distribution of lateral forces to the root and PDLs, protecting the tooth from root fracture or crown/core dislodgement. Ideally, 2mm of circumferential ferrule is desired, with emphasis on walls resisting the most common non-axial forces (e.g., palatal wall for maxillary incisors). Importantly, posts do NOT improve ferrule or resistance to lateral forces; their sole purpose is to retain a core when mechanical retention for the crown is otherwise inadequate, a rare necessity with modern bonding.

  
  

• Endocrowns: For molars with compromised external ferrule, endocrowns offer an alternative by utilizing the internal pulp chamber walls for resistance. These are primarily indicated for root canal treated molars and are best restored with bonded lithium disilicate due to its better bond strength and more compatible modulus of elasticity.

  
  

3. Digital Impressions: The Predictability Revolution

The course highlighted the significant advancements in digital impression technology, moving beyond mere accuracy to focus on workflow predictability.

• Advantages: Digital impressions offer instant feedback on margin capture and occlusal clearance, eliminate stone model issues, and are generally more accurate than conventional PVS impressions.

  
  

• Predictable Scanning Techniques:

  
  

  • OptraGates and Fixed Retractors: Essential for minimizing movement during scanning, which prevents stitching errors and ensures smoother scans.

    
    

  • Meticulous Isolation: Digital scanners are unforgiving; any blood or saliva on the margin will prevent accurate capture. Isolation needs to be pristine.

    
    

  • "Scanner Sees Something It's Seen Before": This golden rule guides the scanning sequence, ensuring continuous reference points for accurate stitching.

    
    

  • Less is More: Minimizing scanning areas reduces stitching errors, leading to greater accuracy (e.g., quadrant scans can be more accurate than full-arch for single units if no value is gained from a full scan).

    
    

  • Bite Scanning: Take the bite scan over the area of interest (the crown prep), ensuring the most accurate registration at the critical site. Patients should bite down firmly and stably but without clenching or moving, and tongue retraction is crucial to avoid foreign body interference.

    
    

  • Pre-preparation Scanning: Useful in specific situations like terminal molars or complex full-arch cases where the occlusion might significantly change post-prep, or when you want the lab to copy the pre-existing tooth morphology.

    
    

  • Clearance Assessment Tools: Digital scanners provide immediate occlusal clearance checks with color maps, allowing for chairside adjustments to ensure adequate restorative space and material thickness.

    
    

• Soft Tissue Management: Achieving a "sulcular space" around the margin is vital for digital scanning. This involves using a double retraction cord technique (triple zero and zero cord), soaking in hemostatic agents (e.g., Hemodent), and carefully removing the second cord to visualize the margin and a clear space before scanning. Laser troughing is an alternative in extreme cases, surprisingly showing less recession than retraction cord in some studies.

  
  

4. Cementation, Materials, and Occlusion: The Art of Integration

This section, featuring a detailed cements overview by prosthodontist Dr. Marijana Eic, demystified the complex world of dental cements and material selection.

• Luting vs. Bonding:

  
  

  • Luting relies on mechanical retention and passive fit (e.g., zinc phosphate, glass ionomer, resin-modified glass ionomer).

    
    

  • Bonding involves active chemical adhesion and micromechanical retention, significantly strengthening the restoration, especially for weaker materials.

    
    

  • Resin Modified Glass Ionomer (RMGIC): Often the go-to cement for crowns with adequate retention and resistance form, offering a balance of strength, fluoride release, and easy clean-up (e.g., Zircad Cement, FujiCEM).

    
    

  • Adhesive Resin Cements: Preferred when maximum bond strength is needed (e.g., veneers, onlays, restorations with poor retention form). Both light-cured (for color stability and extended working time, especially for multiple anterior units) and dual-cured options are used.

    
    

• Material-Specific Cementation Protocols:

  
  

  • Glass Ceramics (e.g., Lithium Disilicate/EMAX): Require hydrofluoric acid etching (to create micromechanical retention) followed by a silane-containing primer (for chemical bonding, e.g., Monobond Plus) and an adhesive resin cement. Bonding significantly increases their fracture resistance.

    
    

  • Zirconia: Cannot be etched. Requires air particle abrasion (sandblasting with aluminum oxide) to create roughness, followed by an MDP-containing primer (e.g., Monobond Plus for its MDP component) and an adhesive resin cement. For full-coverage zirconia crowns with adequate retention, luting with RMGIC is often sufficient, as bonding does not significantly increase zirconia's intrinsic strength.

    
    

• Crown Material Selection:

  
  

  • Zirconia (e.g., Zircad Prime): Available in various yttria concentrations (3Y, 4Y, 5Y), balancing strength (3Y being strongest, most opaque) with translucency (5Y being most translucent, weakest). Selection depends on the tooth's location (posterior vs. anterior) and aesthetic requirements. Monolithic occlusal surfaces are preferred for strength, with layering reserved for facial aesthetics.

    
    

  • Lithium Disilicate (e.g., EMAX): Weaker than zirconia if conventionally luted, but its strength is significantly enhanced by adhesive bonding. Used for veneers and anterior crowns where high translucency is desired. Both pressed and milled options exist, with pressing often preferred for ultra-thin veneers for better internal adaptation.

    
    

• Occlusion Assessment and Adjustment:

  
  

  • Articulating Paper Limitations: Studies consistently show articulating paper is highly inaccurate for assessing occlusal load, producing too many false positives/negatives.

    
    

  • Shim Stock for Verification: Shim stock (8 microns thick) is crucial to confirm occlusal contactsmarked by articulating paper. Dr. Edher emphasized always confirming a high spot with shim stock before adjusting.

    
    

  • Bite Registration Material: Useful for assessing occlusal clearance and identifying high spots across multiple teeth, especially in larger cases, through transillumination.

    
    

  • Systematic Occlusion Protocol: Dr. Edher outlined a systematic approach: pre-determining 2-3 positive contact points on the existing dentition, ensuring the crown maintains these contacts and makes its own contact, and then refining occlusion after cementation. Excursive movements (canine guidance or group function) must also be checked.

    
    

• Temporization: Proper temporization is crucial for patient comfort and tissue health. Techniques include direct and indirect mockups, meticulous trimming (using Soft-Lex discs), and polishing the margins to minimize soft tissue irritation. For multiple units, temporaries should be splinted as a bridge to prevent tooth drifting.

  
  

• Maintenance & Complication Management: The course stressed the importance of patient education on maintaining restorations and the importance of well-fitting crowns for gingival health. Transparent discussions about potential complications, such as post-operative sensitivity or restoration failure, are vital for managing patient expectations.

  
  

In Conclusion

This Crown and Bridge workshop by the BC Dental Study Club and Dr. Faraj Edher was more than just a lecture series; it was an interactive experience designed to elevate clinical practice. The depth of evidence-based information, combined with Dr. Edher's candid sharing of his extensive clinical experience and practical tips, provided attendees with a robust framework for predictable and successful crown and bridge procedures. The emphasis on patient communication, meticulous technique, and leveraging modern technology truly set this course apart.

We extend immense gratitude to Dr. Edher and the entire BC Dental Study Club team for their hard work, unwavering support, and commitment to fostering a community of highly skilled and compassionate dental professionals. We eagerly anticipate future educational opportunities from this exceptional group!