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From Luke’s Journal Sept 2025 | Vol. 30 No. 2 | Success-Failure

Something I hear almost weekly as a dentist is, “How long is this new crown going to last?”

To be honest, it can be a tricky question to give a straight answer to, and many dentists would provide a loose estimate as there are various biologic, technical, and patient-related factors that can affect the longevity of intraoral restorations.¹

Most dentists would agree that one important measure of success in clinical dental practice would be the longevity of the restorations placed in the mouth. Whether it is a crown in the mouth, a retaining wall in the backyard, or a new bull bar on a four-wheel drive, we expect our investments to withstand the test of time.

There are also several factors that contribute to enduring faith in Christians.

Christ followers, like crowns, are subject to various external and internal factors that can affect strength and longevity. This may seem like a far-fetched comparison. Nonetheless, I would like to explore what contributes to enduring faith in Christ followers, and look at the similarities between lasting crowns and lasting Christians.

Prosthodontics 101

A crown is a restoration placed over a tooth, providing partial or full coverage of the coronal tooth structure. Crowns are indicated when there is substantial loss of natural tooth structure, commonly as a result of dental caries or trauma.² Their purpose is to repair existing structural loss, prevent future structural loss, restore lost function, and maintain or improve appearance.³ The extent of the tooth’s structural loss is the primary factor when deciding the type of restoration to be used to treat the tooth. Direct restorative materials, such as composite resin, allow for conservative intracoronal restorations (fillings) of simple to moderate deficiencies in tooth structure. Large direct restorations are more prone to failure due to the limited physical properties of the material and the increased degree of difficulty of placing them in the mouth. There are many factors that affect the success of dental restorations. For simplicity, I’ll focus on single tooth supported crowns as an example.

Lasting crowns: Factors affecting the survival of crowns

A) Recurrent caries

A significant reason for the failure of crowns placed in the mouth is recurrent (secondary) dental caries around restorative margins.⁴ The relationship between the crown margin and the underlying tooth structure is a key factor for recurrent caries risk. The relationship is dependent on the quality of tooth preparation, the quality of the fabricated crown, and the clinician’s skills when cementing the crown into place. These factors directly correlate with the risk of recurrent caries under a crown.⁵ Patients who are at a high risk of dental caries (those with limited hydration, an acidic oral environment, and poor oral hygiene) are also more prone to recurrent caries. Fracture of the restoration or underlying tooth structure also affects the likelihood of recurrent caries as it allows food and bacteria to accumulate in the voids.⁴

B) Tooth vitality

Tooth vitality significantly influences the survival rate of crowns.⁴ Below the enamel and dentin of the teeth lies the pulp, a highly innervated and vascularised mass. The interdental receptors within the pulp prevent excessive masticatory forces being applied to teeth. Loss of such feedback removes this protective alarm system and can increase the probability of fractures.²

A non-vital tooth (a tooth with a dead pulp) is a tooth that has lost its blood supply and innervation. A non-vital tooth may have its pulp removed as part of endodontic treatment. This treatment often leads to further loss of intracoronal tooth structure, especially during the access and instrumentation phases. Thus, endodontic treatment adversely affects the structural integrity of the affected tooth, reducing the tooth’s survival.²

Non-vital teeth are often so structurally weakened that a post and core is placed prior to crown placement to help with retention and resistance. This introduces additional internal stress points, and coupled with the lack of natural tooth structure following endodontic treatment, the fracture risk of the non-vital teeth is increased, leading to a greater likelihood of crown failure.²

C) Material choice

The choice of crown material is another factor that influences survival rate of crowns.² Single crowns are usually made from metal alloys, metal bonded to ceramic, or are completely ceramic.

There has been an increasing trend towards all-ceramic restorations in recent years due to the aesthetic advantages of ceramic restorations, biocompatibility, and improved physical properties.⁶ In particular, zirconia ceramics have emerged as the material of choice for single tooth posterior crowns due to the high flexural strength of the material.⁷ Historically, cast metal was the material of choice for indirect crowns, due to strength, ease of fabrication by casting, and thus biocompatibility due to good marginal adaptation. As the demand for improved aesthetics increased, metal fused to ceramic restorations became popular. However, the fracture of the veneered ceramic was a common issue.⁷

“As the demand for improved aesthetics increased, metal fused to ceramic restorations became popular.”

All-ceramic restorations are an alternative to veneered restorations. However, all-ceramic crowns lacked the compressive and flexural strengths required to withstand the masticatory forces of posterior teeth. In contrast, monolithic zirconia restorations have excellent strength properties and can eliminate the risk of failure of a veneered outer layer, making them an increasingly popular choice for single tooth posterior crowns.⁸ The high strength of monolithic zirconia allows for less invasive reduction of tooth structure during the tooth preparation process for a crown compared to veneered metal crowns, therefore, improving the long-term vitality and survival.⁶

D) Parafunctional movements

Bruxism, or the conscious and unconscious clenching and grinding of teeth, is a parafunctional movement of teeth and a significant factor that detrimentally affects the survival rate of single crowns.² Long term bruxism reduces the clinical height of teeth (shorter teeth), leading to less retention for dental crowns. Along with excessive masticatory forces associated with bruxing, crown retention is compromised, and fracture of the underlying tooth structure often occurs, resulting in treatment failure.²

E) Position in the mouth

The antero-posterior location of the crown in the mouth affects the success of a dental crown.² Although posterior teeth are subject to greater masticatory forces, the survival rate of anterior teeth has been found to be less in many studies.² Masticatory forces on posterior teeth are roughly parallel to the long axis of the teeth, however, in anterior teeth they are not, causing unfavourable load on anterior teeth and therefore a higher risk of failure². Additionally, anterior teeth have less tooth mass protecting the underlying pulp than posterior teeth. As such, there is a higher prevalence of crowned anterior teeth with posts and cores placed in them. As discussed earlier, this adversely affects the success rate of crowned teeth.²

F) Systemic factors

Systemic biologic factors also play an integral role in the survival of crowns.⁹ Cancer treatment, such as radiation, can damage salivary glands and lead to xerostomia. Various medications can also reduce salivary flow. Salivary dysfunction increases the risk of recurrent dental caries and, therefore, failed crowns.⁹ Neurologic diseases, such as Parkinson’s disease and Alzheimer’s disease, can trigger excessive and parafunctional movements of the mandible, increasing the risk of crown failure.⁹ Diabetes mellitus adversely affects the periodontal health of individuals, increasing the likelihood of plaque retention and thereby increasing the risk of restorative failure.⁹ Also, poor periodontal health reduces the survival rate of the entire tooth as a whole, thereby indirectly affecting the success rate of restorations placed on periodontally compromised teeth.⁹ Similarly, smoking adversely affects periodontal health, thus, adversely and indirectly affects the longevity of dental restorations.⁹

Lasting Christians: Spiritual longevity

A) Relationship with God through scripture and prayer

Central to persevering Christian faith is an unwavering relationship with God through meditating on the word of God, prayer and worship. Psalm chapter 1 gives an outline for enduring faith, a comparison between the longevity of the righteous and the destruction of sinners.

“Blessed is the one who does not walk in step with the wicked or stand in the way that sinners take or sit in the company of mockers, but whose delight is in the law of the Lord, and who meditates on his law day and night. That person is like a tree planted by streams of water, which yields its fruit in season and whose leaf does not wither— whatever they do prospers.” (Psalm 1:1-3 NIV).

These verses show that daily devotion with God through Scripture is central to the life of the righteous – not just reading God’s word, but “finding delight” in it. John chapter 15 compares closeness with God to branches requiring constant sustenance from a central vine in order to produce fruit.

“Remain in me, as I also remain in you. No branch can bear fruit by itself; it must remain in the vine. Neither can you bear fruit unless you remain in me. I am the vine; you are the branches. If you remain in me and I in you, you will bear much fruit; apart from me you can do nothing.” (John 15:4-5 NIV).

A strong connection with God through regular prayer, worship and reading scripture is imperative for lasting faith in believers.

An active connection with God is comparable to an active connection between a tooth and the rest of the body – tooth vitality. A vital tooth is stronger internally than a non-vital tooth, much the same as the spiritual strength of those committed to God. A vital tooth receives neurological feedback, which prevents overloading. Similarly, God guides us away from sin through constant feedback. Tooth vitality provides stronger support for a dental crown, and a “vital” relationship with God, one that is alive and strong, equates to spiritual strength and longevity.

B) The right environment

Psalm 1:1 contrasts the righteous with those who find themselves in a corrupt environment, “the wicked”, “sinners”, and “mockers”. Such an environment leads to destruction. It can be difficult for a Christian to grow in their faith if they continually place themselves in sin-filled environments. The parable of the sower in Luke chapter 8 illustrates how the word of God must be placed in the correct soil for it to grow and flourish. The soil needs to be nutrient-rich for strong roots to form from the seed. Shallow soil hinders the development of strong roots, as do thorns. Endurance of faith in Christians cannot be reliant on enthusiasm and emotion – it requires a deep relationship with God fostered in a godly environment.

Intraoral environmental factors, such as bruxism, the anterior-posterior position of the tooth, poor oral hygiene, acidic oral environment, and various systemic factors, were previously mentioned as risk factors for the survival of crowns. A tooth in the right environment has a higher chance of supporting a crown. Similarly, a Christ follower who chooses to be in the right environment is more likely to grow and maintain their faith.

C) Godly character

A steadfast relationship with God fosters righteousness within a believer.

^“But the fruit of the Spirit is love, joy, peace, forbearance, kindness, goodness, faithfulness, gentleness and self-control. Against such things there is no law.” (Galatians 5:22-23 NIV).

Evidence of such character attributes in a person shows spiritual maturity and strength of faith.

Crown materials differ in physical properties. Materials, such as zirconia, are known for their superior physical properties that contribute to strength and longevity. Similarly, the strength of a person’s “spiritual properties” (godly character) contributes to their spiritual longevity.

D) Resisting sin through careful preparation

Ephesians chapter 6 shows how the armour of God is required to resist sin and the devil’s temptations. The important thing to note about putting on the armour of God is that it is proactive rather than reactive. Pre-emptive righteous living, trust in Scriptural truths, peace that is found in trusting God, faith that comes from knowing God, and the promise of salvation are all described as part of the armour of God. Such preparation allows for the spiritual reserves of a believer to be built up to withstand external temptations.

The prevention of dental caries and tooth fractures can be likened to resisting sin through preparation (putting on the armour of God). Drilling well-planned and precise tooth preparations and achieving fine margins on crowns allows for easier cleaning of the crowns, thus improving survival. Improving oral hygiene, managing systemic risk factors, and taking measures to lessen parafunctional movements all help to improve the longevity of crowns by lessening the likelihood of recurrent caries and/or fractures.

Lasting crowns and lasting Christians

A lasting crown requires careful planning. It needs to be placed in a favourable oral environment and position in the mouth. The tooth structure must be precisely prepared, allowing for the use of high-strength materials. Tooth vitality greatly improves the likelihood of success.

Likewise, a lasting Christian must be planted firmly in Christian foundations through intentional devotion to God and exhibit signs of inward spiritual strength – all of which is maintained by an unwavering and vital connection with God. Discover how God may bring fruit through your faithfulness in your workplace.

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