Impact of Parafunctional Habits on Prosthetic Success: Considering Occlusion and Functional Dynamics

What are you assessing: the behavior, damage or symptoms?

Sleep and awake bruxism are forms of masticatory muscle activity. The 2018 international consensus distinguishes that activity from its possible clinical consequences and discusses self-report and instrumental assessment. Describing the behavior, examining dental damage and assessing pain are related tasks, but they are not interchangeable findings.

Most of the research considered here concerns bruxism. It should not be generalized to every oral habit. For restorative planning, the question is which part of a study applies to this patient, this prosthesis and the outcome being discussed.

What does the evidence tell us about loading and complications?

Loading measurements do not predict an individual failure

In a small study of 10 participants, Nishigawa, Bando and Nakano (2001) measured nocturnal bite force over three nights and found that it could exceed maximum voluntary daytime bite force in some participants. These measurements describe nocturnal loading; they do not establish a ratio to ordinary chewing forces or predict prosthetic complication rates.

Long-term associations are not prevention trials

In a retrospective study from one specialist clinic, Chrcanovic, Kisch and Larsson (2020) evaluated 709 patients with implant-supported full-arch fixed prostheses over a mean follow-up of 10.7 years. Recorded bruxism was associated with more screw loosening and fracture, ceramic chipping or fracture, and prosthesis failure. These associations do not establish causation, prevention benefits or risks for all types of prosthesis.

This is a reason to discuss the findings in the context of full-arch implant prostheses. It is not a numerical risk estimate for every restoration, or proof that a splint, adjustment or material change will prevent a complication.

Laboratory material performance has a different meaning

In laboratory testing of specified three-unit fixed partial dentures, Heintze et al. (2018) found that fatigue resistance differed between the tested translucent zirconia and lithium disilicate materials and with zirconia connector size. This experiment measured mechanical fatigue performance; it did not measure clinical survival in patients with bruxism or establish a severity-based material prescription.

Before applying that comparison, identify whether the planned restoration resembles the tested material, three-unit design and connector configuration. A mechanical ranking from those specimens cannot be relabelled as a clinical survival ranking for people with bruxism.

How should those findings inform the plan?

Three considerations belong together: what the patient is doing, what damage or symptoms are present, and what the cited evidence actually measured. These are questions to revisit during planning, not a validated sequence of treatments.

Assess the behavior and consequences separately

Distinguish sleep from awake activity, and interpret history, examination and appropriate recordings in context. Describe damage and symptoms separately (Lobbezoo et al., 2018).

Match the evidence to the intended outcome

Laboratory fatigue, muscle activity, pain and prosthesis survival answer different questions. The full-arch cohort reports associations; the three-unit experiment reports mechanical performance.

Plan and review for the individual patient

Relate restorative choices to documented needs and exact product indications. Discuss the purpose of tooth protection, the limits of expected benefit and follow-up rather than promising a universal result.

Is there a proven occlusal scheme for bruxism?

The 2021 implant-restoration consensus found insufficient evidence to identify an occlusal scheme that minimizes complications. It does not establish a standard long-centric clearance, cusp angle, occlusal-table width or implant number for patients with bruxism.

• Cusp Angulation: A two-dimensional finite-element implant model found that cusp inclination and load position affected stress distribution. These findings do not establish a universal clinical cusp angle for patients with bruxism (Rungsiyakull et al., 2011).
• Group Function: An experiment in 10 healthy adults did not detect a difference in masseter electromyographic activity between devices using canine guidance or group function. It did not establish a preferred scheme for severe bruxism or test prosthetic longevity (Borromeo et al., 1995).
• Occlusal Vertical Dimension (OVD): The cited studies do not establish a bruxism-specific increase in vertical dimension or a predictable effect on muscle tension. Decisions about restorative space require an individual clinical indication.

These modeling and appliance-study findings do not establish a universal occlusal prescription or a percentage increase in restoration lifespan. Their populations, methods and measured outcomes need to be considered when applying them to restorative care.

Why does irreversible adjustment need a separate indication?

A 2023 randomized trial enrolled 17 healthy women with sleep bruxism; four were excluded from analysis. At follow-up averaging 14.4 months, it reported greater reductions in sleep muscle-activity episode frequency and duration after removal of occlusal interferences than after smoothing sharp margins without changing contacts.

This small study does not establish improved prosthetic survival or a general indication to reshape teeth for bruxism. Adjustment needed to correct a defined restorative problem is a separate clinical indication.

What can management reasonably aim to achieve?

Tooth protection, symptom management and restorative repair address different needs. NIDCR describes mouth guards as an option for separating and protecting teeth. That purpose should be distinguished from suppressing bruxism activity or extending prosthesis survival.

The table summarizes different kinds of evidence. It is not a head-to-head ranking, and the cited studies do not establish that one management package prevents peri-implant bone loss, eliminates headache or reduces treatment costs.

The splint, biofeedback and material-modification rows describe different outcomes: tooth protection, sleep-bruxism activity, facial-muscle pain and laboratory fatigue performance. They do not form a common ranking of clinical prosthesis survival. These studies report different outcomes and do not provide a shared comparison of complexity or patient acceptance.

Medication and behavioral evidence require outcome-specific interpretation

Medication and botulinum toxin treatment require individualized clinical assessment. Small placebo-controlled trials of amitriptyline did not show statistically significant reductions in sleep-bruxism muscle activity or associated pain (Mohamed et al., 1997; Raigrodski et al., 2001). Small trials of botulinum toxin type A have reported short-term reductions in selected measures of muscle activity, but effects on bruxism episodes and patient-reported symptoms have varied (Shim et al., 2020; Cruse et al., 2022). Temporary chewing weakness and injection discomfort have been reported.

A trial in patients with single-arch implant overdentures also recorded mechanical complications (Ali et al., 2021), but findings in that specific population do not establish protection for all prosthetic restorations. Treatment decisions should account for the clinical indication, potential adverse effects, and follow-up.

Evidence for behavioral approaches differs between sleep and awake bruxism. For sleep bruxism, a randomized trial found small improvements in both a multicomponent cognitive behavioral program and an occlusal-splint group, without significant between-group differences (Ommerborn et al., 2007). A systematic review found that evidence for CBT benefit in adult sleep bruxism remained limited (Minakuchi et al., 2022). For awake bruxism, a separate systematic review suggested possible benefits of behavioral approaches, while emphasizing limited and heterogeneous evidence (Graham et al., 2026).

Product indications are more useful than a catalogue ranking

A restorative ceramic and an occlusal-guard material serve different purposes. For example, the BruxZir Esthetic Milling Blanks instructions describe anterior and posterior restorations; they do not establish a guard design or suitability for severe bruxism. Use the current instructions for the exact product rather than transferring an indication or durability claim from another material.

Fit, use and response also need individual review. Adherence, changing activity patterns and the limits of assessment methods complicate follow-up; they should be discussed without implying that one contact scheme or appliance is optimal for everyone.

What is still being investigated?

Instrumented splints remain an area of research. Robin and colleagues reported home recordings over 10 consecutive nights using a wireless instrumented splint to characterize clenching and grinding events. This demonstrated monitoring capability in the studied setting; it did not show longer prosthesis survival. The device-specific biofeedback trial discussed above also does not establish that all wearables prevent damage or provide continuous protection.

What does one digital rehabilitation case show?

Stanley and colleagues reported a man with a chipped maxillary central-incisor veneer and tooth wear they attributed to bruxism. Initial records and a trial mock-up were made in 2015; definitive treatment resumed in 2017. This is a documented clinical and digital workflow, not an instrument-confirmed sleep-bruxism case or a controlled test of treatment efficacy.

For DDS readers, the value is seeing how clinical records, digital planning and delivery connect, while keeping that illustration separate from evidence that the treatment reduces bruxism or improves long-term survival.

The sequence below follows the report from initial assessment to treatment completion. The last clinical photographs and occlusal recording belong to the completion phase; they should not be mistaken for a six-month recall examination.

Choose a numbered step, swipe sideways, or use the Previous and Next links. Each step includes its clinical explanation and source figure.

1. Step 1 of 9

   Baseline clinical photographs, 2015

   

   The frontal and occlusal views document the dentition before rehabilitation. They support inspection of the reported wear and restorative problem; photographs alone do not quantify sleep or awake bruxism.

   Open larger Figure 1 (new tab)

   Next step

2. Step 2 of 9

   Initial digital record

   

   The initial intraoral scan records the upper and lower arches. In the reported workflow, those records were combined with facial and functional documentation for planning.

   Open larger Figure 3 (new tab)

   Previous stepNext step

3. Step 3 of 9

   Models and trial mock-up

   

   The authors used models and a matrix for a trial mock-up before definitive treatment. The reported trial illustrates how the proposed rehabilitation was explored; it does not establish a standard increase in vertical dimension.

   Open larger Figure 5 (new tab)

   Previous stepNext step

4. Step 4 of 9

   Records when treatment resumed, 2017

   

   After an approximately two-year interruption, new intraoral records were obtained before treatment restarted. These are updated pretreatment records, not a two-year outcome.

   Open larger Figure 8 (new tab)

   Previous stepNext step

5. Step 5 of 9

   Digital planning

   

   The digital planning view connects the clinical record to the proposed restoration design. It documents this team's design stage; it does not by itself establish improved clinical survival.

   Open larger Figure 11 (new tab)

   Previous stepNext step

6. Step 6 of 9

   Fabricated restorations

   

   The restorations are shown on laboratory models. The report describes digital design and milling. The material inconsistency discussed below prevents using this case as a material-selection or bonding protocol.

   Open larger Figure 12 (new tab)

   Previous stepNext step

7. Step 7 of 9

   Adhesive delivery

   

   The report describes a trial insertion to assess marginal fit and appearance before adhesive delivery. This close-up illustrates the delivery phase. Product-specific surface treatment and bonding values should come from the correct current instructions.

   Open larger Figure 13 (new tab)

   Previous stepNext step

8. Step 8 of 9

   Post-treatment clinical views

   

   The frontal and occlusal views document the restored dentition after treatment. They are an observed post-treatment result, not evidence of long-term durability.

   Open larger Figure 15 (new tab)

   Previous stepNext step

9. Step 9 of 9

   Occlusal recording at treatment completion

   

   The report describes occlusal adjustment and a T-Scan recording during completion, followed by an acrylic protective appliance. Relative contact-force and timing information does not establish a bruxism diagnosis, reduction in activity or cure.

   Open larger Figure 17 (new tab)

   Previous step

Clinical Recommendations

For the dentist

1. Separate the indication from the behavior. Describe sleep or awake activity, damage and symptoms before deciding what needs treatment. Bruxism assessment does not itself prescribe a restoration or a particular occlusal adjustment (assessment consensus; implant occlusal consensus).

2. Explain the outcome you are trying to influence. Tooth protection, pain relief and prosthesis survival are different goals. Use the table's source-specific findings to explain the limits of a proposed approach, rather than presenting a reduction in muscle activity as proof of longer restoration survival.

3. Keep the published case in proportion. Stanley's report illustrates records, planning and delivery for one patient. Its six-month observation cannot demonstrate that changing vertical dimension cures bruxism or establishes a generally successful restorative protocol.

For the dentist and laboratory

1. Identify the exact material and tested design. Compare a laboratory result with the planned prosthesis and connector configuration before applying it. The Heintze experiment supports interpretation of its tested specimens, not a severity-based clinical prescription.

2. Resolve material identity before choosing the processing instructions. The VITABLOCS classification mismatch shows why a paper's product label must be checked against the manufacturer's exact product information. A restorative-material indication also cannot be transferred to an occlusal guard.

A useful plan makes its uncertainties explicit and reviews the individual response. None of the cited evidence supplies a universal cusp angle, guard-material ranking or guaranteed increase in prosthesis lifespan.