The impact of tooth mobility and occlusal trauma (OT) on periodontal bone loss and need for therapy has been debated for many years. This paper summarizes the relevant literature reported in three Dental Clinics of North America articles in the late 1990s, and adds newer information from the 2000s. Principle findings indicate that strong evidence of mobility and OT impacting tooth longevity is lacking, but reducing inflammation in the surrounding periodontium remains a critical treatment. Occlusal therapy when mobility is increasing, comfort or function are compromised, or periodontal regeneration procedures are planned should be considered.
Key points
- •
Occlusal trauma and tooth mobility are associated with periodontal bone and attachment loss. It follows that over many years, this association may lead to enough destruction of periodontal support to threaten periodontal longevity. However, strong evidence of cause and effect is lacking.
- •
Tooth mobility may enhance the probability for further attachment loss during periodontal maintenance therapy, but most mobile teeth can be maintained in function and comfort for many years.
- •
Increasing mobility during periodontal maintenance therapy is a concern, because it may indicate increased deterioration of the periodontium. This may be a result of increasing size of the lesion of occlusal trauma (periodontal ligament space) from increased forces, or from loss of periodontal attachment. Accurate initial measurement of mobility, and monitoring for change over time, is often overlooked in clinical practice. Systematic methods for recording mobility changes need to be integrated into recall protocols.
- •
Control of periodontal inflammation is a key element in minimizing the progression of periodontal attachment loss associated with excessive occlusal forces. Reduction of inflammation should precede definitive occlusal therapy, and occlusal therapy usually should precede periodontal regenerative surgery when significant mobility exists in the teeth targeted for regenerative therapy.
- •
Occlusal therapy is also important in improving the function and comfort of the dentition, which may also enhance the desire by the patient to retain teeth, thereby increasing tooth longevity.
Historical evidence
Several articles in Dental Clinics of North America in the late 1990s reviewed the state of knowledge as to the impact of trauma from occlusion and mobility on periodontitis. Occlusal trauma was defined as an injury (usually a histologically demonstrable lesion) to the attachment apparatus or tooth as a result of excessive occlusal forces. Common symptoms of occlusal trauma were described to include pain or discomfort, dental hypersensitivity, tooth mobility (fremitus), or pathologic migration of teeth. Classic animal studies by Lindhe and colleagues using a dog model suggested that experimental occlusal trauma alone does not initiate periodontal pockets or periodontal attachment loss, but requires concomitant inflammatory periodontal disease. Treatment of periodontitis and control of inflammation in the presence of experimental occlusal trauma reversed periodontal disease activity. However, monkey studies by Polson and colleagues found minimal changes in the rate of periodontal attachment loss when experimental occlusal trauma was combined with inflammatory periodontal disease, but no regeneration of bone took place when experimental occlusal trauma was removed in the presence of active inflammation. Osseous regeneration occurred only when both occlusal trauma and periodontal inflammation were eliminated, but with reduced level of periodontal attachment resulting from the previous loss.
Although most tooth mobility is not the result of occlusal trauma, mobility is one of the primary clinical signs of occlusal trauma. However, Ericsson and Lindhe concluded that increased tooth mobility did not exacerbate clinical attachment loss caused by plaque-induced periodontitis.
Human clinical studies reviewed in Dental Clinics of North America were sparse, mostly because of the difficulty in performing such investigations. Cross-sectional evaluations or investigations where mobility was noted included the finding that teeth with mobility may have a detrimental effect on postsurgical healing (following curettage, modified Widman, or pocket elimination surgery) and do not gain as much attachment. More recent evidence that mobility impacts surgical outcomes was reported by Cortellini and colleagues showing that baseline tooth mobility was significantly associated with reduced clinical attachment gains following procedures to regenerate deep intrabony defects.
Occlusal contacts, even if abnormal, do not necessarily lead to occlusal trauma, but excessive occlusal forces by definition are a needed initiator of the injury of occlusal trauma. Early work indicated that abnormal occlusal contacts were associated with increased periodontal bone loss and mobility, yet later studies were contradictory. Pihlstrom and coworkers found that occlusal contacts (centric relation, working, nonworking, or protrusive) did not lead to more severe periodontitis than in teeth without these contacts. Ismail and colleagues reported on a group of 165 subjects who were re-examined for clinical attachment loss following a 28-year evaluation period, and determined that increased age, smoking, and tooth mobility were the factors most closely related to attachment loss. Wang and colleagues reported that mobile teeth had significantly more attachment loss during the maintenance years than the nonmobile teeth. Jin and Cao found no significant difference in probing depth, clinical attachment level, or bone height loss in teeth with or without abnormal occlusal contact, but teeth with mobility or widened periodontal ligaments had greater probing depths, more attachment loss, and increased alveolar bone loss. McGuire and Nunn found that parafunctional habits and mobility were correlated with worsening prognosis and tooth loss over 5 to 8 years of periodontal maintenance.
In a rare interventional trial, Burgett and colleagues found that occlusal adjustment designed to reduce occlusal trauma resulted in a 0.4-mm improvement in mean probing attachment compared with patients with no occlusal adjustment over a 6-year period. However, there was no significant difference in mobility between those receiving occlusal adjustment and those who did not.
The evidence reported in these manuscripts, written near the turn of the century, is summarized in Box 1 . It is the purpose of this current review to analyze subsequent literature to cast new light on the question “Do mobility and occlusal trauma impact periodontal longevity?”
- •
Occlusal trauma is a risk factor in the progression of periodontitis, but routine occlusal treatment may not be necessary for successful periodontal maintenance outcomes.
- •
Tooth mobility may result from a variety of factors in addition to occlusal trauma, but there does seem to be a relationship between tooth mobility and progressing periodontitis.
- •
Occlusal trauma and mobility may threaten periodontal longevity and impede successful therapy, thereby prompting consideration of occlusal therapy along with inflammation control.
Historical evidence
Several articles in Dental Clinics of North America in the late 1990s reviewed the state of knowledge as to the impact of trauma from occlusion and mobility on periodontitis. Occlusal trauma was defined as an injury (usually a histologically demonstrable lesion) to the attachment apparatus or tooth as a result of excessive occlusal forces. Common symptoms of occlusal trauma were described to include pain or discomfort, dental hypersensitivity, tooth mobility (fremitus), or pathologic migration of teeth. Classic animal studies by Lindhe and colleagues using a dog model suggested that experimental occlusal trauma alone does not initiate periodontal pockets or periodontal attachment loss, but requires concomitant inflammatory periodontal disease. Treatment of periodontitis and control of inflammation in the presence of experimental occlusal trauma reversed periodontal disease activity. However, monkey studies by Polson and colleagues found minimal changes in the rate of periodontal attachment loss when experimental occlusal trauma was combined with inflammatory periodontal disease, but no regeneration of bone took place when experimental occlusal trauma was removed in the presence of active inflammation. Osseous regeneration occurred only when both occlusal trauma and periodontal inflammation were eliminated, but with reduced level of periodontal attachment resulting from the previous loss.
Although most tooth mobility is not the result of occlusal trauma, mobility is one of the primary clinical signs of occlusal trauma. However, Ericsson and Lindhe concluded that increased tooth mobility did not exacerbate clinical attachment loss caused by plaque-induced periodontitis.
Human clinical studies reviewed in Dental Clinics of North America were sparse, mostly because of the difficulty in performing such investigations. Cross-sectional evaluations or investigations where mobility was noted included the finding that teeth with mobility may have a detrimental effect on postsurgical healing (following curettage, modified Widman, or pocket elimination surgery) and do not gain as much attachment. More recent evidence that mobility impacts surgical outcomes was reported by Cortellini and colleagues showing that baseline tooth mobility was significantly associated with reduced clinical attachment gains following procedures to regenerate deep intrabony defects.
Occlusal contacts, even if abnormal, do not necessarily lead to occlusal trauma, but excessive occlusal forces by definition are a needed initiator of the injury of occlusal trauma. Early work indicated that abnormal occlusal contacts were associated with increased periodontal bone loss and mobility, yet later studies were contradictory. Pihlstrom and coworkers found that occlusal contacts (centric relation, working, nonworking, or protrusive) did not lead to more severe periodontitis than in teeth without these contacts. Ismail and colleagues reported on a group of 165 subjects who were re-examined for clinical attachment loss following a 28-year evaluation period, and determined that increased age, smoking, and tooth mobility were the factors most closely related to attachment loss. Wang and colleagues reported that mobile teeth had significantly more attachment loss during the maintenance years than the nonmobile teeth. Jin and Cao found no significant difference in probing depth, clinical attachment level, or bone height loss in teeth with or without abnormal occlusal contact, but teeth with mobility or widened periodontal ligaments had greater probing depths, more attachment loss, and increased alveolar bone loss. McGuire and Nunn found that parafunctional habits and mobility were correlated with worsening prognosis and tooth loss over 5 to 8 years of periodontal maintenance.
In a rare interventional trial, Burgett and colleagues found that occlusal adjustment designed to reduce occlusal trauma resulted in a 0.4-mm improvement in mean probing attachment compared with patients with no occlusal adjustment over a 6-year period. However, there was no significant difference in mobility between those receiving occlusal adjustment and those who did not.
The evidence reported in these manuscripts, written near the turn of the century, is summarized in Box 1 . It is the purpose of this current review to analyze subsequent literature to cast new light on the question “Do mobility and occlusal trauma impact periodontal longevity?”
- •
Occlusal trauma is a risk factor in the progression of periodontitis, but routine occlusal treatment may not be necessary for successful periodontal maintenance outcomes.
- •
Tooth mobility may result from a variety of factors in addition to occlusal trauma, but there does seem to be a relationship between tooth mobility and progressing periodontitis.
- •
Occlusal trauma and mobility may threaten periodontal longevity and impede successful therapy, thereby prompting consideration of occlusal therapy along with inflammation control.
Recent evidence: occlusal trauma and mobility impact on periodontitis progression
Support for abnormal occlusal contacts, which may lead to occlusal trauma, as a risk factor in periodontitis progression and eventually tooth longevity was found in a series of retrospective studies by Harrel and Nunn. These authors reported that teeth with occlusal discrepancies had significantly deeper probing depths and worse prognoses and mobility. Occlusal discrepancies were defined as differences between retruded position (centric relation) and maximum intercuspation (centric occlusion), and working and balancing contacts in lateral and protrusive movements. After adjusting for other risk factors, such as smoking and poor oral hygiene, occlusal discrepancy continued as an independent contributor to increased probing depths.
Furthermore, teeth with untreated occlusal discrepancies had a significantly greater increase in probing depth per year than teeth without initial occlusal discrepancies or with occlusal treatment designed to correct occlusal discrepancies. In fact, only teeth with untreated occlusal discrepancies showed a significant increase in probing depth during periodontal maintenance (0.066 mm/year over an undefined period, at least 1 year). The authors concluded that occlusal treatment reduces the progression of periodontitis.
Finally, characterization of the occlusal discrepancies revealed that deeper probing depths were associated with premature contacts in centric relation (0.89 mm), posterior protrusive contact (0.51 mm), balancing contacts (1.01 mm), and combined working and balancing contacts (1.13 mm, all P <.0001). Although this series of studies had several major shortcomings, including a small sample size (<100), lack of standardized treatment and appropriate longitudinal evaluation protocols, and not being randomized or blinded, they do suggest that discrepancies potentially leading to occlusal trauma could impact progressive periodontal breakdown, even during periodontal maintenance.
The importance of nonworking (balancing) side contacts was extended in a large cross-sectional epidemiologic study, wherein it was reported that nonworking side contacts only were related to probing depth ( P <.0001) and attachment loss ( P = .001), although it was weak in terms of magnitude and specificity. In another cross-sectional investigation, the number of premature and balancing contacts increased with the severity of periodontitis (loss of clinical attachment, P <.001). The authors concluded that secondary trauma from occlusion, which was erroneously defined as premature and balancing contacts, is positively correlated with the severity of attachment loss. The lack of longitudinal data limits determination of the role of occlusal trauma in periodontal longevity.
A recent systematic review of occlusal adjustment in periodontal therapy found no new evidence to encourage the use of routine occlusal adjustment to maintain periodontal health. However, it was concluded that it is not detrimental, and occlusal adjustment in conjunction with periodontal therapy may improve patient comfort and function. A similar conclusion was reached in a review article on the biologic effects of occlusal trauma, based on evidence primarily from animal studies.
Potential indications and scientific rationale for reducing occlusal trauma in periodontitis
Although reduction of occlusal trauma by occlusal therapy has not been proved to be a mandatory part of routine periodontal therapy, are there certain comorbidities that accelerate the damage caused by occlusal trauma? Kawamoto and Nagaoka found that ovariectomized rats subjected to experimental occlusal trauma demonstrated significantly more bone resorption around the periodontal ligament than sham-treated animals. Nicotine also enhanced bone loss in rats with combined occlusal trauma and ligature-induced periodontitis compared with animals without either nicotine or both nicotine and occlusal trauma. de Oliveira Diniz and colleagues confirmed that occlusal trauma augmented the bone loss seen with ligature-induced periodontitis in rats, and this effect was further enhanced by diabetes mellitus. These rat studies suggest that attempts to reduce occlusal trauma in certain vulnerable cohorts, such as those with estrogen deficiency, diabetes, or smoking habits, may have merit, or at least deserves further investigation.
The scientific rationale for how occlusal trauma may contribute to increased periodontal bone loss has received some attention over the past decade. Central to occlusal trauma-induced (and periodontitis-induced) bone resorption seems to be stimulation of receptor activator of nuclear factor kappa B ligand (RANKL), the primary driver of osteoclast activation. RANKL interacts with RANK receptor on osteoclasts to initiate bone resorption. In a rat model where occlusal trauma was initiated by raising the occlusal surface, immunohistochemistry demonstrated RANKL associated with osteoclasts and osteoblasts. A similar occlusal trauma protocol combined with lipopolysaccharide-induced periodontitis extended the length of time that osteoclasts were present on the interproximal bone surface, and the increased expression of RANKL in osteoclasts, endothelial cells, inflammatory cells, and periodontal ligament cells. Human periodontal ligament cells exposed to mechanical stress also increased interleukin-6 production, a potent stimulator of RANKL, periodontal inflammation, and bone resorption.
The recent evidence for occlusal trauma and mobility impacting tooth longevity is summarized in Box 2 .
