The biological effects of occlusal trauma on the stomatognathic system - a focus on animal studies

Apical periodontitis after intense bruxism

BACKGROUND

Bruxism is known to cause masticatory muscle pain, temporomandibular joint pain, headaches, mechanical tooth wear, prosthodontic complications and cracked teeth. Less known to the practitioner, and described only experimentally in literature, is that bruxism can also damage the pulp. To our knowledge, this is the first known clinical case of a patient developing apical periodontitis due to bruxism.

CASE PRESENTATION

This article presents the case and successful treatment of a 28-year-old healthy male patient with apical periodontitis on teeth 36 and 46 requiring root canal treatment after an intense phase of bruxism. Due to an unclear diagnosis, treatment had been delayed.

CONCLUSIONS

Incomprehensible tooth pain can be the result of bruxism. Practitioners need to be informed that intense bruxism can possibly lead to apical periodontitis. It is important, therefore, that a thorough anamnesis is collected and taken into account during diagnostics.

Occlusal trauma inhibits osteoblast differentiation and bone formation through IKK-NF-κB signaling

BACKGROUND

Occlusal trauma is an important factor promoting bone loss caused by periodontal diseases. Although there are reports of traumatic force promoting bone resorption in periodontal diseases, no studies examining the inhibition of bone formation by traumatic force and the underlying mechanism have been reported. The aim of this study was to investigate the mechanism whereby traumatic force inhibits bone formation.

METHODS

MC3T3-E1 cells were induced to undergo osteogenic differentiation and subjected to cyclic uniaxial compressive stress with or without stimulation with Pg. LPS. The expression of osteoblast markers and the activation of IKK-NF-κB signaling were evaluated in vitro. Then, MC3T3-E1 cells were induced to undergo osteogenic differentiation and subjected to cyclic uniaxial compressive stress with or without IKK-2 Inhibitor VI. The expression of osteoblast markers was determined. Then, the classic Wnt signaling pathway (β-catenin, Gsk3β, p-Gsk3β, and Dkk1) was further evaluated in vitro. Finally, occlusal trauma was induced in Wistar rats with or without the injection of IKK-2 Inhibitor VI, to evaluate changes in bone mass and IKK-NF-κB and Wnt/β-catenin signaling in vivo.

RESULTS

After stimulation with Pg. LPS and traumatic force, IKK-NF-κB signaling was significantly activated in vitro. The expression of osteoblast markers and the activity of alkaline phosphatase in MC3T3-E1 cells declined after traumatic force loading and were rescued when IKK-NF-κB signaling was blocked. Wnt/β-catenin signaling was accordingly inhibited upon force loading, but this inhibition was reversed when IKK-NF-κB was antagonized in vitro. X-ray and Micro-CT analysis of the mandibles of the rats as well as HE and TRAP staining showed that bone loss induced by occlusal trauma declined after IKK-NF-κB was inhibited. The expression of p65 and IκBα was increased when occlusal trauma was induced in Wistar rats, whereas β-catenin, OCN, and Runx2 levels were decreased. After blocking IKK-NF-κB, significant upregulation of β-catenin, OCN, and Runx2 was observed in rats suffering from occlusal trauma.

CONCLUSIONS

IKK-NF-κB signaling could be activated by traumatic force or occlusal trauma. Its activation promoted the degradation of β-catenin, ultimately inhibiting osteogenic differentiation in vitro and bone formation in vivo.

Evaluation of bone loss due to primary occlusal trauma in two experimental models of occlusal overload

Abstract Introduction Primary occlusal trauma (OT) is an injury of the periodontium with normal height as a result of occlusal forces which exceed their adaptive capacity. Objective To evaluate, histometrically, the alveolar bone loss in the furcation region of rats experimentally submitted to 2 models of occlusal overload. Material and method 45 animals randomly divided into 3 groups: Occlusal Interference (OI, n = 15) - fixing an orthodontic wire segment on the occlusal surface of the first lower molar; Occlusal Overload (OO, n = 15) - wearing of the cusps of the lower contralateral molars, the second and third molars next to the first molar that had its dimensions maintained; Negative Control (NC, n = 15) - evaluation of the initial dimensions of the periodontal ligament (PL). Five animals / group were sacrificed after 14, 21 and 28 days. Result Intergroup evaluation showed significant bone loss in OI (p<0.001) and OO (p<0.01) compared to NC. OI had significantly higher bone loss compared to OO at 14 (p<0.01), 21 (p <0.01) and 28 days (p<0.01). The intragroup evaluation showed no significant influence of time on bone loss in OI and OO, regardless of the technique used (p>0.05). The thickness of the PL remained stable in NC (p>0.05). Conclusion OI and OO were effective in the experimental reproduction of OT, and OI promoted greater alveolar bone loss compared to OO, showing that the impact of occlusal overload in OI increased the extent of the OT injury.

Do Mobility and Occlusal Trauma Impact Periodontal Longevity?

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.

Loss of pulp vitality after maxillary sinus augmentation: a surgical and endodontic approach

BACKGROUND

Maxillary sinus augmentation is a routine procedure performed in implant dentistry in cases with sinus pneumatization. This study presents a series of clinical cases in which tooth devitalization occurred in conjunction with sinus augmentation.

METHODS

In the three cases presented, a sinus-lift procedure was performed that resulted in devitalization of the adjacent teeth. Patients were referred to an endodontist for evaluation and treatment. Vitality of the teeth was determined by the use of a cold test, electric pulp test, and cavity test. The pulp was considered to be necrotic if the tests were negative.

RESULTS

In this case series, loss of pulp vitality of two maxillary left second premolars and one maxillary left first molar occurs after sinus-augmentation procedures. The devitalized teeth were free of caries. In one case, two amalgam restorations were present.

CONCLUSION

Pulp necrosis may occur in conjunction with a sinus-lift procedure in cases when an adjacent root is in close proximity to the sinus floor and the sinus membrane is elevated over the root apex.