Mechanisms of mechanical force aggravating periodontitis: A review

Periodontitis is a widespread oral disease accompanied by uncontrolled inflammation-related tissue destruction. Periodontitis is related to various factors. Among them, occlusal trauma can aggravate the severity of periodontitis and has been attracting a great deal of attention. We systematically searched PubMed and Web of Science databases for related articles. Keywords for the search were "mechanical force", "mechanical stress", "occlusal trauma" and "periodontitis". This review focuses on the effect of mechanical forces on periodontitis and discusses the possible pivotal targets participating in this process. We elucidated and summarized 21 articles that reported on our topic. Several biological processes and pathways that participate in enhancing the inflammatory response to mechanical stress have been studied, including the regulation of osteogenesis and osteoclastic resorption balance, Yes-associated protein signaling, induction of collagen destruction, and regulation of programmed cell death. Mechanical force enhances the process of periodontitis in multiple ways. However, currently, no studies have further examined its underlying mechanism. Understanding the specific roles of mechanical forces may assist in the treatment of periodontitis with traumatic occlusal trauma.

Association between clinical manifestations of occlusal trauma and magnetic resonance imaging findings of periodontal ligament space

OBJECTIVES

The purpose of this study was to evaluate the association between clinical manifestations of occlusal trauma of the teeth and maximum signal intensity of periodontal ligament space on MRI.

METHODS

20 subjects (males: 9, females: 11, mean age: 35.9 ± 14.0 years, range: 22-65 years) participated in this study. Subjective symptoms of bruxism, tooth mobility, fremitus, occlusal contact area, occlusal force, widening of the periodontal ligament space, and thickening of the lamina dura were defined as clinical manifestations of occlusal trauma. The total number of clinical manifestations was used to evaluate the degree of clinical occlusal trauma, with a score of 7 indicating the highest degree of occlusal trauma. The maximum signal intensity in the periodontal ligament space was evaluated by a specific T2 weighted MRI sequence: IDEAL image.

RESULTS

Spearman's rank correlation between the total clinical occlusal trauma score and maximum signal intensity in the periodontal ligament space was 0.529 for all teeth, 0.517 for anterior teeth, and 0.396 for molar teeth (p < 0.001 for all).

CONCLUSIONS

A significant correlation between the degree of occlusal trauma and the signal intensity of the periodontal ligament space suggests a new potential MRI-based method for objectively determining occlusal trauma.

Radiographic signs of excessive occlusal forces are associated with marginal bone loss: a retrospective clinical study

OBJECTIVES

Work in animal models has implicated excessive occlusal forces and occlusal trauma as co-destructive factors for periodontitis. The main aim of the present study was to make a radiographic assessment of the effects of excessive occlusal forces, ie occlusal/incisal tooth wear, widening of the periodontal space, and the presence of a mandibular torus, on interproximal marginal bone loss in a large series of patients. A secondary aim was to evaluate the statistical correlation between the parameters in two specific teeth and those of 12 teeth for marginal bone loss and six teeth for occlusal/incisal tooth wear within the same individual.

METHOD AND MATERIALS

A total of 1,950 full-mouth radiographic surveys were analyzed retrospectively. Interproximal marginal bone loss was quantified relative to the root length (Schei ruler technique). In addition, occlusal/incisal tooth wear and periodontal ligament space widening of the periodontal space were assessed, as well as the presence of a mandibular torus. Odds ratio and logistic regression analysis were used to determine the association between occlusal trauma and marginal bone loss.

RESULTS

The correlation of the measured parameters between the values for specific teeth and the whole dentition was evaluated from data from the first 400 radiographs. Teeth 41 and 33 showed the best correlation to the whole dentition: 0.85 for interproximal marginal bone loss, 0.83 for widening of the periodontal space, and 0.97 for occlusal/incisal tooth wear. The results of a logistic regression analysis with age as an independent variable, revealed a significant association between bone loss and both tooth wear (odds ratio = 2.767) and bone loss and widening of the periodontal space (odds ratio = 2.585).

CONCLUSION

Tooth wear was positively correlated to both widening of the periodontal space and marginal bone loss. No correlation was found between the presence of a mandibular torus and marginal bone loss.

Goldenhar Syndrome and Pain-Related Temporomandibular Disorders. A Case Report

Goldenhar syndrome (GS) is a development syndrome, characterized by incomplete development of the craniofacial region. The involvement is mainly unilateral; it varies from being mild to severe; and it can range from malocclusion and facial asymmetry to a more complex phenotype with complete absence of the mandibular ramus and temporomandibular joint. However, orthopedic symptoms of orofacial pain and dysfunction have not generally been considered as part of the symptom complex in GS cases. The case presented here is of a 15-year-old Caucasian patient, who was referred for evaluation because of bilateral pain in the masticatory muscles and temporomandibular joints.

Oral parafunctions, piercing and signs and symptoms of temporomandibular disorders in high school students

OBJECTIVE

The use of chewing-gum and piercing has become common among adolescents and might result in increased oral muscle activity and overloading. Aim To investigate the frequency of oral piercing and parafunctions in relation to symptoms of temporomandibular disorders (TMD) among adolescents.

MATERIALS AND METHODS

One hundred and twenty-four third level high school students, living either in a city or in a small town, enrolled in either science or media programmes, were included. The students completed a questionnaire regarding different parafunctions and symptoms of TMD. A clinical examination of the temporomandibular system and estimation of the tooth wear was performed in 116 students.

RESULTS

Chewing-gum was used by 86% of the students (25% with a daily use) and 14% had an oral piercing. The science students used more chewing gum than the media students (p = 0.008), while the media students had more piercings (p < 0.001). Symptoms once a week or more were reported with 39% for headache, 18% for clicking, 7% for facial pain and 6% for difficulty to open wide. Girls reported more headaches (p = 0.007) and more severe symptoms (p = 0.003), had more medical consultations and used more analgesics (both p < 0.05) and had more clinical signs (p = 0.01) than boys. Girls had more oral piercings and used more chewing gum than boys (both p < 0.05). The media students had more sick leave (p < 0.01) than the science students. Chewing-gum use was associated with headache (p < 0.01), with difficulty to open wide (p < 0.05) and with tenderness of the temporomandibular joints and muscles (both p < 0.05). Oral piercing was associated with headache and muscle tenderness (both p < 0.05) and daily nail biting with headache (p < 0.05) and tooth wear (p = 0.004).

CONCLUSIONS

There is an association between use of chewing gum, nail biting, oral piercing, and symptoms of TMD.

Fixed prosthodontic treatment outcomes in the long-term management of patients with periodontal disease: a 20-year follow-up report

PURPOSE

The aim of this long-term cohort study was to evaluate the efficacy and complications of fixed partial dentures in a convenience sample of 100 patients with periodontal disease who were treated and maintained periodontal patients after 20 years.

MATERIALS AND METHODS

After active treatment, including periodontal surgery and endodontic and prosthetic treatment, patients were enrolled in a supportive periodontal care (SPC) program with 3- to 6-month recalls. All patients showed clinical data recorded at (1) the original consultation (T0), (2) the first SPC visit following the completion of prosthetic treatment (T1), and (3) at the latest SPC clinical session 20 years after T1 (T2). Multivariate analyses were performed to investigate the influence of clinical variables on the risk of prosthetic abutment (PA) loss after 20 years' visits.

RESULTS

The final sample comprised 100 patients. At T1, a total of 948 PAs represented the original sample of experimental teeth. At the 20-year follow-up, a total of 854 PAs (90.1%) were still in function, while 94 (9.9%) PAs in 41 patients (41%) were lost during SPC; 98% of lost PA were endodontically treated. Vertical root fracture (48%) was the major cause of PA loss, while progression of periodontitis caused 31% of PA loss. Age (P = .002), Full-Mouth Plaque Score (P < .0001), Full-Mouth Bleeding Score (P = .0002), and oral parafunctions (P = .0083) were associated with increased probability of PA failure. Among clinical-related factors, endodontic treatment (P = .0082), root resection/ amputation (P < .0001), multi-rooted teeth (P = .0005), and abutment associated with parafunction (P < .0001) were associated with increased risk of abutment loss after 20 years.

CONCLUSIONS

Perioprosthetic treatment in compliant patients is highly successful after 20 years of SPC.

Non-Orthodontic, Non-Restorative Closure of Acquired Diastemata

AIM

To illustrate the reversibility of "pathologic tooth migration" in several patients that were managed by periodontal therapy alone, along with a review of the relevant literature.

BACKGROUND

Pathologic tooth migration (PTM) is a common phenomenon among patients seeking dental care. Different etiologic factors have been implicated in PTM: loss of periodontal support, occlusal interferences, posterior bite collapse, and various oral habits such as: lip biting, tongue thrusting, and playing wind instruments. Identification of all the causative factors involved in PTM is crucial for a successful treatment outcome. Managing severe cases of acquired diastemata may necessitate a complex and a sequential intervention involving periodontic, orthodontic and prosthodontic measures. However, "spontaneous regression" of teeth to their original position may occur in certain cases after elimination of the offending factors.

CONCLUSION

"Spontaneous" closure of acquired diastemata could occur following surgical and/or non-surgical periodontal therapy or removal of occlusal interferences. Correction of pathologically migrated teeth without orthodontic or restorative treatment is feasible, but unpredictable.

An Investigation Into the Relationship Between Noncarious Cervical Lesions and Premature Contacts

The aim of the present study was to investigate the relationship between noncarious cervical lesions (NCCL) and dental premature contacts (PC). Following examination of 1,974 teeth from 77 patients referred to the Department of Oral Medicine, Faculty of Dentistry, Mashad University of Medical Science, Iran, a total of 167 teeth were identified to have the criteria set for noncarious cervical lesions (regarded as NCCL group). Also, 167 teeth exhibiting no such lesions were selected randomly from the same population (regarded as control group). The results indicated that within the NCCL group, the frequency of noncarious cervical lesions differed significantly among the various teeth; the first premolar teeth showed the greatest number of cervical lesions, followed by the canine teeth, and the second molar teeth had the least number of lesions. A similar trend was detected in the total number of premature contacts among the seven types of teeth. The results revealed a highly significant and positive correlation between the incidence of NCCL and the PC. The NCCL group and the control group differed significantly in the number of premature contacts in centric relation (CR) and working side, but not in balancing and protrusion.

Aetiology of a diagnosis: the key to success in treatment planning

Aetiology is the cause of a diagnosis. The essential key for the determination ofaetiology is a thorough examination: the history of the problems, the crucial elements in function, and habits. Our case report involves progression of a malocclusion and aggravation of the gum recessions which resolved following root planing and fixed orthodontic correction for the underlying cause, malocclusion, without any gum graft procedures.

Differential diagnosis of orofacial pain and temporomandibular disorder

When a patient complains of orofacial pain, health care providers must make a correct diagnosis. Doing this can be difficult, since various signs and symptoms may not be specific for 1 particular problem or disorder. One initially should formulate a broad differential diagnosis that can be narrowed after analysis of the history and examination. In this article, orofacial pain is categorized as being caused by: intracranial pain, headaches, neuropathic pain, intraoral pain, temporomandibular disorder, cervical pain, pain related to anatomically associated structures, referred pain, or mental illness.

Occlusal trauma in mixed dentition: literature review

Controversy over the relationship between occlusion and the progression of periodontal destruction has been ongoing since the beginning of scientific studies of dental diseases. This paper reviews the literature and explores the relationship between trauma from occlusion with periodontal disease in children, presenting recommendations for clinical practice based on the available evidence.

Clinical evaluation of the association of noncarious cervical lesions, parafunctional habits, and TMD diagnosis

OBJECTIVE

To verify a potential association between the presence of noncarious cervical lesions, parafunctional habits, and temporomandibular disorder (TMD) diagnosis.

METHOD AND MATERIALS

Sample-size calculation provided a value of 130 participants with a confidence level of 95% and an error margin of 5%. A population of 132 volunteers (30 men: mean age, 23.7 ± 3.05 years; 102 women: mean age, 24.9 ± 5.86 years) underwent an oral examination and was interviewed by a trained dentist. The following parameters were registered: personal details, TMD diagnosis, parafunctional habits, and noncarious cervical lesion presence. The population was then divided into a noncarious cervical lesion group and a control group and subjected to the t test, chi-square test, Fisher exact test, and Spearman correlation (α = .05).

RESULTS

Noncarious cervical lesions were present in 39% of the population, with the largest concentrations found in the maxillary premolars (32%). The data showed a significant association between noncarious cervical lesion presence, tooth clenching (P = .03), and nail biting (P = .02), as well as a relation with TMD diagnosis (Fonseca Index [P = .01] and Research Diagnostic Criteria for TMD (RDC/TMD) [P = .004] ). In the noncarious cervical lesion group, direct rank correlation was found between maxillary premolars and clenching (P = .03), mandibular canines and nail biting (P = .05), and mandibular incisors and parafunctional habits without dental contacts (P = .02).

CONCLUSION

Parafunctional habits and TMD presence should be taken into account in the diagnosis and treatment plan of noncarious cervical lesions.

Effects of experimental occlusal interferences in individuals reporting different levels of wake-time parafunctions

AIMS

To test the hypothesis that the effects of an experimental occlusal interference differ between individuals reporting a high or low frequency of wake-time oral parafunctions.

METHODS

Study participants reporting very high (HFP group; n = 10) or very low (LFP group; n = 10) levels of oral parafunctions were selected by means of a questionnaire administered to 200 medical students. The selected participants wore an experimental occlusal interference in a single-blind longitudinal study, which comprised different occlusal conditions: interference free (IFC) and active occlusal interference (AIC). Assessments included clinical examination, measurements of nonfunctional tooth contacts, state and trait anxiety, and visual analog scale scores for occlusal discomfort, masticatory muscle pain, and headache. Data were analyzed by repeated measures twoway analysis of variance on ranked data, followed by calculation of within- and between-group differences using Friedman tests and Mann-Whitney tests, respectively.

RESULTS

During AIC, the frequency of nonfunctional tooth contacts significantly decreased in both groups (median [interquartile range, IQR]: in HFP from 55.3% [60.0%] to 31.1% [33.5%], P = .03; in LFP from 31.8% [32.4%] to 14.0% [22.8%], P < .01), the decrease being more pronounced in LFP than in HFP (P < .01). Trait anxiety was significantly higher (P = .01) in the HFP group (median, IQR = 22.5, 9.0) than in the LFP group (median, IQR = 19.0, 3.0). The interference caused more occlusal discomfort in the HFP group than in the LFP group (P = .02) and was associated with a significant increase of masticatory muscle pain (P = .05) and headache (P = .04) only in the HFP group.

CONCLUSION

The application of an experimental occlusal interference has a different effect in individuals reporting a high or low frequency of oral parafunctions.

Can traumatic occlusion cause endodontic problems? A case report

Radicular cysts are commonly found odontogenic cysts in the jaws. The lesion is diagnosed mainly in young patients during the second decade of life. In the majority of cases, it is asymptomatic. This paper reports a rare case in which traumatic occlusion was identified as the etiology of a radicular cyst. Endodontic treatment was performed and the traumatic occlusion also was corrected. A six-month follow-up appointment found good healing of the periapical region.

Secondary trauma from occlusion and periodontitis

OBJECTIVE

To assess the association between secondary trauma from occlusion and the severity of periodontitis.

METHOD AND MATERIALS

A total of 288 subjects with chronic periodontitis of varying severity and 93 healthy subjects were included in the study. Premature and balance contacts were identified by manual palpation and visualization of occlusal contacts during clenching in habitual intercuspation and lateral or protrusive movements of the mandible. Statistical analysis was performed with Kruskal-Wallis, Mann-Whitney, and Spearman correlation tests.

RESULTS

Statistically significant differences (P<.001) were found for all variables tested (ie, the total amount of trauma per patient and the number of premature and balance contacts increased significantly with the level of clinical attachment loss). The Spearman test showed a statistically significant correlation between the total amount of trauma per patient and the severity of periodontitis (P<.001).

CONCLUSION

The results of this study indicate that secondary trauma from occlusion (ie, premature and balance contacts) is frequently seen in periodontally compromised patients and is positively correlated with the severity of attachment loss.

Some dogmas related to prosthodontics, temporomandibular disorders and occlusion

It is the aim of this paper to give a few examples of dogmas related to prosthodontics and oral implants and to discuss the controversial role of occlusion in the aetiology of temporomandibular disorders. New knowledge is developing at a rapidly increasing rate in dentistry, as in other areas of society. Our lecturers at university taught us many useful things. But, as time goes by, what is still relevant? Some methods are so well established that they deserve to be called dogmas. It is implied that a dogma is not supported by strong evidence, even though it has existed and been practised for a long time. In the era of evidence-based dentistry it is appropriate to scrutinize such issues. A review of the current literature indicates that conflicting opinions exist concerning a number of common procedures in clinical dentistry, mainly due to a scarcity of good studies with unambiguous results. There is therefore a need for more high-quality clinical research in attempting to reach the goal of evidence-based clinical practice. The dental community should take an active part in this process.

Evaluation of multiple implant-bone parameters on stress characteristics in the mandible under traumatic loading conditions

PURPOSE

The inter-relationships between various implant and bone parameters were evaluated for their influence on the von Mises stress distribution within the mandible using the finite element procedure. The maximum compressive stresses in cancellous and cortical bone were compared to the published stress-strain data to determine bone fracturing status when the maximum (traumatic) loading is applied.

MATERIALS AND METHODS

Parameters considered herein include the implant diameter and length. Also considered are Young's modulus of cancellous bone and that of cortical bone, along with its thickness. The implant-bone system was modeled using two-dimensional plane strain elements, 50% osseointegration between implant and cancellous bone was assumed, and linear relationships were assumed between the stress value and Young's modulus of both cancellous and cortical bone at any specific point within the mandible.

RESULTS

Implant length was more influential than implant diameter within cancellous bone, whereas implant diameter was more influential in cortical bone. A ranking of all the parameters indicated that the applied masticatory force had a more significant influence on the stress difference, in both cancellous and cortical bone, than all other parameters. Young's modulus of cortical bone and implant length were least influential in cancellous and cortical bone, respectively. Under traumatic loading, cancellous bone fractured for all parameter combinations. When all parameters were set to their average values, the cortical bone did not fracture under traumatic loading. However, it fractured if all the parameters were all set to the minimum values.

CONCLUSION

Quantitative evaluation and ranking of the major implant and bone parameters will help provide practical guidelines that are useful for the design and testing of dental implants. The study may also be of interest to dental professionals in evaluating possible implant placement options under various clinical scenarios.

Orthodontic treatment of localised gingival recession associated with traumatic anterior crossbite

BACKGROUND

Gingival recession can be defined as the apical shift of the marginal gingiva from its normal position on the crown of the tooth to levels on the root surface beyond the cemento-enamel junction. The aetiology of this condition is multifactorial, but can result from a traumatic occlusion. The long-term prognosis of teeth with localised gingival recession can be uncertain. Successful management of these cases may involve either orthodontic or periodontal treatment in isolation or in combination.

AIM

To describe two patients in which localised gingival recession associated with anterior crossbites were corrected with orthodontic appliances.

METHODS

A 2 x 4 appliance and an upper removable appliance were used to correct the crossbites.

RESULTS

Correction of the anterior crossbites resulted in a clinical improvement of the gingival recession. The aetiology and management of localised gingival recession is discussed.

CONCLUSIONS

Simple orthodontic appliances can be used to provide interceptive treatment to correct localised crossbite and enhance the overall long-term prognosis of the lower incisors. To achieve optimal results multidisciplinary involvement is recommended.

Occlusal features and masticatory muscles activity. A review of electromyographic studies

OBJECTIVE

Since there is no consensus on the association between occlusion and temporomandibular disorders (TMDs), the aim of the present paper was to conduct a review of electromyographic studies, in order to asses the relationship between various occlusal features and masticatory muscles' activity.

MATERIAL AND METHODS

An exhaustive MEDLINE computer search was performed to identify all experimental studies present in the English literature describing the relationship between the electromyographyc evaluation of patients and their occlusal morphology.

RESULTS

The search methodology provided a total of 102 abstracts and from these 11 full reports were required as full text. Of the 11 articles selected, 8 studied the variation of the muscular activity as a consequence of the experimental introduction of occlusal disturbances whereas the remaining three studies estimated the electrical muscular characteristics without any artificial alteration of the occlusal morphology.

CONCLUSION

The results obtained seem to suggest that occlusal features can affect the electrical signals recordings of masticatory muscles. Further researches are strongly requested to realize if this altered muscular activity can turns in the occurrence of TMDs.

Dental occlusion and periodontal disease: what is the real relationship?

ABSTRACT The role of occlusion in periodontal disease has always been a challenging topic. A good understanding of the current status of the relationship of occlusion and periodontitis is of paramount importance in order for dental clinicians to provide adequate and comprehensive periodontal treatment in patients presenting with traumatic occlusion. This article reviews the literature regarding the relationship between occlusion and periodontitis and presents recommendations for clinical practice based on available evidence. Clinical cases illustrating the complexity of this relationship and their management are presented.

Evaluation of temporomandibular joint noise in partially edentulous patients

In order to evaluate the presence of TMD (temporomandibular disorder), dissatisfaction related to the use of removable partial dentures (RPD) and the effect of the treatment on temporomandibular joint noises, 13 female patients with Kennedy class I and II mandibular arch were selected. Another 13 young, asymptomatic, dentate patients, also female, were used as reference. After four years, 38.4% were found to have a moderate or severe degree of TMD. Over the four years, the degree of TMD increased in 46.15% of the patients, was not affected in 20.07%, while in 15.38% it decreased or the patients remained free from signs and symptoms. About 30% of the patients at the second year and 46% after the fourth year, had complaints regarding retention and stability. It was concluded that there is no relationship between TMD and the condition of partially edentulous Kennedy class I and II, but patient dissatisfaction increased after the second year and temporomandibular joint noise was reduced significantly with the replacement of the teeth.

Peri-implant bone loss caused by occlusal overload: repair of the peri-implant defect following correction of the traumatic occlusion. A case report

The purpose of this case report is to demonstrate the relation between occlusal overload and peri-implant bone loss and the reversal of the situation after removal of the offending forces. The placement of an unstable removable prosthesis on 3 well-integrated implants that had been stable for 9 years caused noticeable bone loss after 6 months. The elimination of the traumatic occlusion reversed the situation, and a remarkable healing of the peri-implant tissue occurred until the pretrauma condition was nearly restored. The condition has been stable for the past 4 years.

Computerized occlusal analysis technology and Cerec case finishing

Computerized occlusal analysis is becoming the principal tool available to clinicians with which to understand functional and parafunctional forces of occlusal contact, contact timing sequences, and occlusal surface interface pressures, which arise as teeth mill against each other during mandibular movements. Because recent research on articulating paper has revealed that articulating paper mark size does not measure occlusal forces predictably, the modern clinician needs to employ an occlusal contact measuring device that can reliably determine aberrant occlusal force concentrations and time prematurities. Computerized occlusal analyses can be used to guide the operator as to which tooth contact locations require appropriate occlusal adjustments. When inserting Cerec restorations, computerized occlusal analysis can be employed to target excessive force concentrations and time premature contacts to better preserve the Cerec materials, than can be accomplished with "articulating paper-only" occlusal adjusting. This paper describes the evolution of computerized occlusal analysis, the system attributes, and illustrates its use in case-finishing Cerec bonded lingual guidance veneers.

Occlusion and periodontal disease--where is the link?

The effect of occlusion on the periodontium has been the subject of much debate. Interest on this subject has decreased over the years but has been renewed with the popularity of implant dentistry. This paper reviews the literature and explores the relationship between trauma from occlusion with periodontal disease and peri-implant bone loss. With regards to periodontal disease, there are two schools of thought on the effect that trauma from occlusion has on the periodontium. One believes that trauma from occlusion is a co-destructive factor in the initiation and progression of periodontal disease. The other believes that it is not. Up till now, there are no conclusive explanations on the association between trauma from occlusion and periodontal disease. For dental implants, current literature suggests that there is an association between occlusal overloading and peri-implant bone loss even in the absence of inflammation. However, there is a need for more randomized clinical trials to validate this relationship.

In vivo evaluation of noncarious cervical lesions in sleep bruxism subjects

STATEMENT OF PROBLEM

Occlusal load has frequently been suggested to be involved in the development of a noncarious cervical lesion (NCL). However, there is a lack of clinical studies evaluating NCLs and occlusal parameters in sleep bruxism (SB) subjects.

PURPOSE

The purpose of this clinical study was to assess the frequency of NCLs and determine potential occlusal differences between SB subjects and healthy control subjects.

MATERIAL AND METHODS

A total of 91 volunteers, 58 women and 33 men, with a mean (SD) age of 28.37 (4.89) years (range of 20 to 39 years), participated in this investigation. The clinical assessment of SB was based on the criteria of the American Academy of Sleep Medicine. The participants were divided into 2 groups; 58 subjects were assigned to the SB group and 33 subjects to the control group, following a thorough dental examination that was performed by a single trained dentist. Additionally, the following parameters were recorded: mean number of teeth present, existence/absence of NCLs, frequency of NCLs relating to the type of tooth, type of occlusal guidance scheme, existence of a slide from centric occlusion (CO) to maximum intercuspation (MI), length of the slide, and report of tooth hypersensitivity. Group differences were statistically analyzed using chi-square tests for the qualitative variables and Mann-Whitney U tests for the quantitative variables (alpha=.05).

RESULTS

NCLs were significantly more prevalent in SB subjects (39.7%) than in the control subjects (12.1%) (P=.006). In SB subjects, the first premolars were the teeth most affected, and in control subjects, the first molars were most affected. Tooth hypersensitivity was reported in 62.1% of the SB subjects and in 36.4% of the control subjects (P=.018). The evaluation of occlusal guidance schemes revealed no significant difference between the groups. In SB subjects (70.7%), a slide from CO to MI was significantly more prevalent than in control subjects (42.4%) (P=.008). Moreover, SB subjects demonstrated a significantly longer mean (SD) slide of 0.77 (0.69) mm compared to that of control subjects of 0.4 (0.57) mm (P=.008).

CONCLUSIONS

Within the limitations of this study, SB subjects demonstrated significantly more NCLs than the control group; whereas, the type of occlusal guidance scheme seems to be of minor importance in the development of NCLs.

Expression of receptor activator of nuclear factor kappa B ligand relates to inflammatory bone resorption, with or without occlusal trauma, in rats

BACKGROUND AND OBJECTIVE

Receptor activator of nuclear factor kappa B ligand (RANKL) is an important factor in osteoclast differentiation, activation and survival; however, its involvement in inflammatory bone resorption, with or without occlusal trauma, is unclear. The purpose of the present study was to investigate the distribution of RANKL-expressing cells in rat periodontium during lipopolysaccharide-induced inflammation with or without occlusal trauma.

MATERIAL AND METHODS

Lipopolysaccharide was injected into rat gingiva of the lower left first molar to induce inflammation. In addition, the occlusal surface of the upper left first molar of rat was raised by placing a gold inlay to induce occlusal trauma in the lower left first molars. The distribution of RANKL-expressing cells was immunohistochemically observed.

RESULTS

In the inflammatory model, many osteoclasts were observed at the apical inter-radicular septum on day 5 and they were reduced by day 10. On the other hand, in the inflammatory model with occlusal trauma, many osteoclasts were still observed on day 10. RANKL expression was similar to the changes in osteoclast number. The expression of RANKL increased in endothelial cells, inflammatory cells and periodontal ligament cells.

CONCLUSION

These findings clearly demonstrated that RANKL expression on endothelial cells, inflammatory cells and periodontal ligament cells is involved in inflammatory bone resorption and the expression is enhanced by traumatic occlusion. These results suggest that RANKL expression on these cells is closely involved in the increase of osteoclasts induced by occlusal trauma.

Multidisciplinary management of advanced occlusal periodontitis: genioplasty for autogenous block bone grafts

Step-by-step sequencing is essential in the treatment of generalized advanced periodontitis. Mutilated skeletodental malocclusion, muscle imbalance, and loss of dentoalveolar ridges are major complicating factors. The need for osseous ridge augmentation provided an opportunity to address the patient's facial imbalance. Concomitantly, genioplasty camouflaged the vertical facial excess and deficient chin. At the outset, a prosthetic commitment was essential.

Prosthodontic management of angular cheilitis and persistent drooling: a case report

This article describes a case of persistent saliva drooling, and the accompanying chronic angular cheilitis, that is not uncommon in the elderly patient population. A drug therapy and the temporomandibular joint aspect of vertical dimension of occlusion during prosthodontic evaluation and construction are presented. Also described is a method to incorporate a canula into the denture prosthesis to channel the saliva toward the oropharyngeal area for geriatric and handicapped patients who suffer from chronic drooling and angular cheilitis.

Impact of implant overloading on the peri-implant bone in inflamed and non-inflamed peri-implant mucosa

OBJECTIVE

To assess the impact of overloading on peri-implant bone level and the bone-to-implant contact (BIC) in the presence of healthy or inflamed peri-implant tissues.

MATERIALS AND METHODS

Four screw-shaped machined implants were placed bilaterally in the mandible of four beagle dogs and left submerged for 3 months. Prosthetic abutments were connected either in supra-occlusal contact with the opposite teeth (overloaded) or in infra-occlusal position (unloaded). In each dog, cotton floss ligatures were placed unilaterally around abutments to promote plaque accumulation; the contralateral side was brushed three times a week. There were four experimental sites, two implants in each: loaded uninflamed (LU), loaded inflamed (LI), unloaded uninflamed (UU), and unloaded inflamed (UI). Clinical and radiographic parameters were recorded at baseline and every 3 months throughout the observation period. At 12 months, the dogs were sacrificed and histomorphometric analysis was performed.

RESULTS

Implants with ligature-induced peri-implantitis presented high inflammatory indices throughout the observation period. Clinical parameters did not change from baseline for both LU and UU. Loading significantly increased the percentage of BIC (BIC%) (P<0.05) and slightly increased crestal bone resorption, but not apical to the implant neck. Both LI and UI groups showed significant peri-implant bone loss (P<0.01), mostly horizontal on the buccal aspect and angular on the lingual aspect, which exposed implant threads. Loading significantly (P<0.05) increased implant thread exposure due to buccal and lingual vertical bone resorption.

CONCLUSIONS

In the presence of uninflamed peri-implant mucosa, overloading of implants in the dog model increased BIC% and slightly reduced marginal bone level. However, resorption did not progress beyond the implant neck. Overloading aggravated the plaque-induced bone resorption when peri-implant inflammation was present.

Classification of facial asymmetry by cluster analysis

INTRODUCTION

The purposes of this study were to classify patients with facial asymmetry by using the cluster analysis and to evaluate the characteristics of the resultant groups.

METHODS

One hundred consecutive orthodontic patients who had frontal cephalograms and photographs taken for the diagnosis of facial asymmetry were included in the sample. A cluster analysis was used to classify the subjects, with craniofacial measurements related to asymmetry obtained from the cephalograms and photographs.

RESULTS

The subjects were divided into 5 clusters based on only 3 variables from the frontal cephalograms: menton deviation, apical base midline discrepancy, and vertical difference of right and left antegonion. The results of the ANOVA test according to the variables showed statistically significant differences between the groups in all variables, indicating that each group can be easily identified with the variables.

CONCLUSIONS

The results suggest that patients with facial asymmetry can be classified simply based on some variables on frontal cephalograms, and this classification can be helpful in proper diagnosis and treatment planning for these patients.

External cervical resorption associated with traumatic occlusion and pyogenic granuloma

This report describes a rare situation in which external cervical resorption was associated with gingival enlargement (pyogenic granuloma) in the upper left central incisor (tooth 21) in a 28-year-old man. Tissue from the lesion was examined histopathologically; periodontal, endodontic and restorative treatments were performed; and the occlusal disharmony, which had resulted in traumatic occlusion, was corrected. Three years after these treatments, the gingiva is normal and healthy and there is no sign of recurrence of the pathologic enlargement. The patient"s periodontal condition is now routinely evaluated. In the presence of gingival enlargement resulting from inflammation, traumatic occlusion can cause progressive external root resorption.

Hyperalgesia in response to traumatic occlusion and GFAP expression in rat parabranchial nucleus: modulation with fluorocitrate

We have examined, by immunocytochemical methods and nociceptive behavior assessment in rats, whether astrocytes in the parabrachial nucleus (PBN) are involved in the regulation of traumatic occlusion. The expression of glial fibrillary acidic protein (GFAP) in PBN of ipsilateral and contralateral sides was up-regulated 4 h after occlusal changes in molars, reached peak levels at 24 h, and was then gradually down-regulated. PBN astrocytes activated by traumatic occlusion were found to have enlarged cell bodies and thickened processes within 8 h. An inhibitor of glia metabolism (FCA, fluorocitrate) reduced astrocyte activation and significantly attenuated the development of pain hypersensitivity in this model. The results suggested that the GFAP-immunoreactive astrocytes in PBN within the bridge of Varolius were activated by traumatic occlusion, and that they were involved in the transmission and modulation of nociceptive information in the central nervous system. However, although astrocytes in PBN are thus probably involved in causing post-occlusal hyperalgesia, we have not been able to exclude that astrocytes at other locations also contribute to this effect.

Evaluation of temporomandibular disorders in children using limited cone-beam computed tomography: a case report

Considerable advances have been made in dental and orthodontic diagnosis resulting from the development of a device known as a limited cone beam dental compact-CT (3DX). This report documents the diagnostic procedures and treatment performed on an eight year old female patient who presented with clinical signs and symptoms of a temporomandibular disorder (TMD). Evaluation of a bony abnormality of the temporomandibular joint (TMJ) using the limited cone-beam CT (3DX) proved to be of considerable value. A three-dimensional image of the right TMJ showed erosion and flattening of the condyle. Following treatment, there was marked alleviation of the clinical symptoms while considerable improvement of the bony abnormalities was clearly evident on a three-dimensional image.

Current trends in gingival recession coverage--part I: the tunnel connective tissue graft

The recession of the gingiva is increasingly becoming a more prominent condition in the oral health of many patients and should be treated at its earliest detection. The multifactorial etiology, decision modality, and current trends followed in the treatment of gingival recession are discussed in this presentation. The correction of Class I and II gingival recessions are presented as a means of minimizing surgical trauma and achieving predictable aesthetic results. Part II of this discussion will present alternative techniques in treating gingival recession.

Epidemiological evaluation of the multifactorial aetiology of abfractions

The purpose of this study was to determine risk indicators for the aetiology of abfractions (cervical wedge-shaped defects) on teeth using dental and medical variables obtained in a population-based sample of the cross-sectional epidemiological 'Study of Health in Pomerania' (SHIP). Medical history, dental, and sociodemographic parameters of 2707 representatively selected subjects 20-59 years of age with more than four natural teeth were checked for associations with the occurrence of abfractions using a two-level logistic regression model on a tooth and a subject level. The estimated prevalence of developing abfractions generally increased with age. The following independent variables were associated with the occurrence of abfractions: buccal recession of the gingiva, odds ratio (OR) = 6.7; occlusal wear facets of scores 1, 2 and 3, OR = 1.5, 1.9, 1.9; tilted teeth, OR = 1.4; inlays, OR = 1.6; toothbrushing behaviour, OR = 1.9 to 2.0 (two and three times a day versus once a day). First premolars had the highest estimated risk for developing abfractions, followed by the second premolars. Maxillary and mandibular teeth behaved similarly in terms of abfractions, with the exception of mandibular canines, which had a much lower estimated risk of incurring abfractions than did maxillary canines. The results of this analysis indicated that abfractions are associated with occlusal factors, like occlusal wear, inlay restorations, altered tooth position and tooth brushing behaviour. This study delivers further evidence for a multifactorial aetiology of abfractions.

Teeth contacting habit as a contributing factor to chronic pain in patients with temporomandibular disorders

Many different factors are known to cause and perpetuate the symptoms of temporomandibular disorders (TMD). However, the roles of parafunctional factors have not been clearly elucidated. We found one of these habits in the clinical setting. This parafunctional habit involves daily light touching of the upper and lower teeth, when the mouth is closed. We named this habit Teeth Contacting Habit (TCH). [OBJECTIVES] To investigate the following hypotheses: 1) TCH is associated with perpetuation of chronic pain of TMD patients; 2) TCH is associated with other behavioral factors. [METHODS] Two hundred and twenty-nine TMD outpatients with chronic pain were analyzed with multivariate logistic regression models. [RESULTS] TCH was found in 52.4% of patients. Patients with TCH and pain lasting for more than four months were less likely to experience improvements in pain at the first visit (OR = 1.944, p = 0.043). Other factors associated with TCH were as follows: unilateral chewing (OR = 2.802) and involvement in a precision job (OR = 2.195). [CONCLUSION] TCH can prolong TMD pain and is associated with other behavioral factors.

Occlusal interference during mastication can cause pathological tooth mobility

BACKGROUND AND OBJECTIVE

Despite little evidence regarding the relationship between tooth mobility and nonworking contact, the evaluation of occlusion is performed mainly by the detection of premature and/or nonworking contacts during tapping movements and lateral excursion. The hypothesis of this study is that occlusal contact during mastication is potentially traumatic to periodontal tissue. It clarifies the relationship between chewing patterns and the status of periodontal tissue.

MATERIAL AND METHODS

Subjects included 73 adults, 20-29 years of age (39 men and 34 women), with complete sets of teeth and no history of orthodontic treatment or periodontal disease. The closing chewing patterns of each subject were classified into three groups by the Masticatory Deviation Index, which depicts the deviation from the normal chewing patterns within 5 mm from the intercuspal position. Periotest was used to diagnose teeth mobility and the values were compared among the three groups.

RESULTS

The present study indicates that the chewing movements which deviated from the normal chewing movements increased the mobility of specific types of teeth.

CONCLUSION

The results of this study imply a relationship between chewing movements and tooth mobility and indicate that functional evaluation of occlusion is necessary for the examination of periodontal tissue. Occlusal evaluation with border and tapping movements might be insufficient, and functional occlusal evaluation during chewing movements can be clinically useful for using to evaluate periodontal tissue.