The relative importance of plaque and occlusion in periodontal disease

Finite element models: A road to in-silico modeling in the age of personalized dentistry

OBJECTIVE

This article reviews the applications of Finite Element Models (FEMs) in personalized dentistry, focusing on treatment planning, material selection, and CAD-CAM processes. It also discusses the challenges and future directions of using finite element analysis (FEA) in dental care.

DATA

This study synthesizes current literature and case studies on FEMs in personalized dentistry, analyzing research articles, clinical reports, and technical papers on the application of FEA in dental biomechanics.

SOURCES

Sources for this review include peer-reviewed journals, academic publications, clinical case studies, and technical papers on dental biomechanics and finite element analysis. Key databases such as PubMed, Scopus, Embase, and ArXiv were used to identify relevant studies.

STUDY SELECTION

Studies were selected based on their relevance to the application of FEMs in personalized dentistry. Inclusion criteria were studies that discussed the use of FEA in treatment planning, material selection, and CAD-CAM processes in dentistry. Exclusion criteria included studies that did not focus on personalized dental treatments or did not utilize FEMs as a primary tool.

CONCLUSIONS

FEMs are essential for personalized dentistry, offering a versatile platform for in-silico dental biomechanics modeling. They can help predict biomechanical behavior, optimize treatment outcomes, and minimize clinical complications. Despite needing further advancements, FEMs could help significantly enhance treatment precision and efficacy in personalized dental care.

CLINICAL SIGNIFICANCE

FEMs in personalized dentistry hold the potential to significantly improve treatment precision and efficacy, optimizing outcomes and reducing complications. Their integration underscores the need for interdisciplinary collaboration and advancements in computational techniques to enhance personalized dental care.

Evaluation of the Effect of Occlusal Calibration in Periodontitis Patients with Occlusal Trauma Using T-Scan

BACKGROUND

High occlusal forces in patients with untreated periodontitis may reflect occlusal trauma-associated periodontal conditions. Occlusal analysis using T-scan might provide the distribution of occlusal loading forces in periodontitis patients. The study aimed to evaluate the effect of occlusal trauma in periodontitis patients and occlusal calibration using a T-scan.

MATERIALS AND METHODS

A total of 30 periodontitis patients were recruited for the study. Patients were categorized into two groups: Group I: scaling and root planing followed by T-scan recording and no occlusal calibration; Group II: scaling and root planing followed by occlusal calibration using T-scan. Clinical parameters, orthopantomogram (OPG) and T-scan evaluation were evaluated at baseline, 3-month and 6-month intervals.

RESULTS

Significant improvements in clinical parameters were noted at different time intervals after occlusal calibration using T-scan. At 3-month intervals, mean pocket depth showed statistically significant difference among the test group in the right (upper and lower) and left lower quadrant at P = 0.01, 0.002 and 0.005, respectively. Mean clinical attachment level (CAL) showed statistically significant difference among the test group in the right upper, right lower and left lower quadrants at P = 0.02, 0.001 and 0.009, respectively, at 3 months. The comparison of the mean gingival index (GI) at 6 months showed statistically significant difference among test and control groups at 6 months in different study quadrants (P = 1 in right upper, 0.009 in right lower, <0.001 in left upper and <0.001 in left lower). Mean pocket depth at the 6-month follow-up showed statistically significant difference among the test group in all the study quadrants (P = <0.001 in right upper, <0.001 in right lower, 0.003 in left upper and 0.005 in left lower). Mean CAL showed statistically significant difference among the test group in all the study quadrants at 6-month intervals (P = 0.02 in right upper, <0.001 in right lower, 0.01 in left upper and 0.04 in left lower). The bone defect height showed a statistically significant difference only in the right upper quadrant among both the test groups at the 6-month follow-up (P = 0.02). Comparing the mean percentage of force on both sides of the jaw showed a statistically significant difference among the test group at 6 months (P = 0.001 on the left side and 0.001 on the right side).

CONCLUSION

The occlusal correction using T-scan showed a positive association between probing pocket depth (PPD) and CAL at different time intervals from baseline to 6 months when these parameters were compared after occlusal adjustments.

Biomechanical pathways of dentoalveolar fibrous joints in health and disease

Spatial and temporal adaptations within periodontal tissues and their interfaces result from functional loads. Functional loads can be physiologic and/or pathologic in nature. The prolonged effect of these loads can alter the overall biomechanics of a dentoalveolar fibrous joint (dentoalveolar joint) by changing the form of the tooth root and its socket. This "sculpting" of the tooth root and alveolar bony socket is a consequence of several mechano-biological changes that occur within the periodontal complex of a load-bearing dentoalveolar joint. These include changes in biochemical expressions, structure, elemental composition, and mechanical properties of alveolar bone, the underlying tissues of the roots of teeth, and their interfaces. These physicochemical changes in tissues continue to prompt mechano-responsive biochemical activities at the attachment sites of periodontal ligament (soft) with bone (hard), and ligament with cementum (hard), which are the entheses of a load-bearing dentoalveolar joint. Forces at soft-hard tissue attachment sites between disparate materials with different stiffness values theoretically generate strain singularities or discontinuities. These discontinuities under prolonged functional loading increase the probability for failure to occur specifically at the enthesial zones. However, in a normal dentoalveolar joint, gradual stiffness gradients exist from ligament to bone, and from ligament to cementum. The gradual transitions in stiffness from softer ligament (lower stiffness) to harder bone or cementum (higher stiffness) or vice versa optimize tissue and interfacial strains. Optimization of tissue and ligament-enthesial physical and chemical properties facilitates transmission of cyclic forces of varying magnitudes and frequencies that collectively maintain the overall biomechanics of a dentoalveolar joint. The objectives of this review are 3-fold: (i) to illustrate physicochemical adaptations at the periodontal ligament entheses of a human periodontal complex affected by subgingival calculus; (ii) to demonstrate how to "program" the hallmarks of periodontitis in small-scale vertebrates in vivo to generate spatiotemporal maps of physicochemical adaptations in a diseased dentoalveolar joint; and (iii) to correlate dentoalveolar joint biomechanics in healthy and diseased states to spatiotemporal maps of physicochemical adaptations within respective periodontal tissues. This interdisciplinary approach demonstrates that physicochemical adaptations within periodontal tissues using the mechanics of materials (tissue mechanics), materials science (tissue composition), and mechano-biology (matrix molecules) can help explain the mechano-adaptation of dentoalveolar joints in normal and diseased functional states. Multiscale biomechanics and mechano-biology approaches can provide insights into the functional competence of a diseased relative to a normal dentoalveolar joint. Insights gathered from interdisciplinary and multiscale biomechanics approaches include the following: (i) physiologic loads related to chewing maintain a balance between mineral-forming and-resorbing biochemical cellular events, resulting in gradual stiffness gradients at the periodontal ligament entheses, and, in turn, sustain the overall biomechanics of a normal "healthy" dentoalveolar joint; (ii) pathologic loads resulting from tissue degradation and physical changes to the periodontal complex promote an abrupt stiffness gradient at the periodontal ligament entheses. The shift from gradual to an abrupt stiffness gradient could prompt a shift in the biochemical cascades, exacerbate mechano-responsive biochemical expressions at periodontal ligament entheses farther away from the site of insult, and culminate in joint degradation; (iii) sustained pathologic function on periodontally diseased joints exacerbates degradation of periodontal ligament entheses providing insights into "rescue therapy", such as the use of an adequate "mechanocal dose" to regain joint function; and (iv) spatiotemporal maps of changes in biochemical expressions, and physicochemical properties of strain-dominated affected sites, including the periodontal ligament entheses, can guide anatomy-specific therapeutics for tissue regeneration and/or disease control with the purpose of regaining dentoalveolar joint function. Modulation of occlusal loads could minimize disease progression and potentially assist in regaining functional attachment of ligament to bone and/or ligament to cementum of the dentoalveolar joint. Elucidating mechanisms that drive the breakdown of the functionally active periodontal complex burdened with microbes will provide the required critical insights into regenerative medicine and/or biomimetic approaches that would facilitate rescue/regain of dentoalveolar joint function.

Traumatic occlusion aggravates bone loss during periodontitis and activates Hippo-YAP pathway

AIM

This study aimed at exploring changes in YAP expression and their effect on periodontitis (PD) combined with traumatic occlusion (TO).

MATERIALS AND METHODS

BALB/cJ mice were used to establish a PD model by local administration of Porphyromonas gingivalis (P.g, ATCC 33277) and a TO model by occlusal elevation (OE) using composite resin bonding on the bilateral maxillary molar. The mouse fibroblast cell line (L929) and pre-osteoblast cell line (MC3T3-E1) were subjected to cyclic tensile/compressive stress and inflammatory stimuli (lipopolysaccharide from Escherichia coli) to verify in vivo results.

RESULTS

Severe bone resorption was observed by microCT scanning in OE with P.g group, when compared to OE only and P.g only groups. Mechanical stress caused by OE activated the Hippo-YAP pathway in periodontal tissues and upregulated the expression of JNK/AP-1. OE with P.g further promoted the expression of YAP and JNK/AP1, leading to the upregulation of the JNK/AP-1 related inflammatory cytokines TNF-α and IL6. Similar results were obtained when osteoblasts were subjected to mechanical stress in vitro.

CONCLUSIONS

Our study demonstrated that periodontitis with TO caused severe inflammation-induced bone resorption. Activation of YAP and upregulation of JNK/AP-1 induced by TO potentially aggravated the symptoms of PD.

Animal models for periodontal regeneration and peri-implant responses

Translation of experimental data to the clinical setting requires the safety and efficacy of such data to be confirmed in animal systems before application in humans. In dental research, the animal species used is dependent largely on the research question or on the disease model. Periodontal disease and, by analogy, peri-implant disease, are complex infections that result in a tissue-degrading inflammatory response. It is impossible to explore the complex pathogenesis of periodontitis or peri-implantitis using only reductionist in-vitro methods. Both the disease process and healing of the periodontal and peri-implant tissues can be studied in animals. Regeneration (after periodontal surgery), in response to various biologic materials with potential for tissue engineering, is a continuous process involving various types of tissue, including epithelia, connective tissues and alveolar bone. The same principles apply to peri-implant healing. Given the complexity of the biology, animal models are necessary and serve as the standard for successful translation of regenerative materials and dental implants to the clinical setting. Smaller species of animal are more convenient for disease-associated research, whereas larger animals are more appropriate for studies that target tissue healing as the anatomy of larger animals more closely resembles human dento-alveolar architecture. This review focuses on the animal models available for the study of regeneration in periodontal research and implantology; the advantages and disadvantages of each animal model; the interpretation of data acquired; and future perspectives of animal research, with a discussion of possible nonanimal alternatives. Power calculations in such studies are crucial in order to use a sample size that is large enough to generate statistically useful data, whilst, at the same time, small enough to prevent the unnecessary use of animals.

Cyanoacrylate Adhesive as an Alternative Tool for Membrane Fixation in Guided Tissue Regeneration

AIM

To report a well succeeded use of cyanoacrylate adhesive for fixating a resorbable membrane during a guided tissue regeneration procedure (GTR).

BACKGROUND

The immobilization of membranes in GTR is essential for establishing proper environment for cell differentiation and tissue regeneration. However, some membranes are very difficult to be kept in position by sutures and its fixation by mini screws or pins may be time consuming and expensive.

CASE DESCRIPTION

A 47-year-old woman presenting a vertical bone defect at the palatal aspect of the left central incisor was treated by GTR using particulate autogenous bone graft associated to a collagen membrane. The membrane was glued to the bone surrounding the defect and to the tooth surface with cyanoacrylate adhesive. The postoperative period was uneventful and 4 years later, excellent results in terms of radiographic filling of the defect and reduction of the probing depth were seen. For illustrative purposes, histological findings obtained during a previous experiment in calvaria of guinea pigs is shown, characterizing a foreign body granuloma and proving that the cyanoacrylate adhesive is a safe tool in GTR.

CONCLUSION

The use of a membrane glued with cyanoacrylate to immobilize membranes in GTR is viable and safe from both technical and biological standpoints and may be advantageous for clinical and research purposes.

CLINICAL SIGNIFICANCE

The alternative method for membrane fixation shown in this case report can contribute to simplify the technique in GTR procedures.

Cytological Kinetics of Periodontal Ligament in an Experimental Occlusal Trauma Model

Using a model of experimental occlusal trauma in mice, we investigated cytological kinetics of periodontal ligament by means of histopathological, immunohistochemical, and photographical analysis methods. Periodontal ligament cells at furcation areas of molar teeth in the experimental group on day 4 showed a proliferation tendency of periodontal ligament cells. The cells with a round-shaped nucleus deeply stained the hematoxylin and increased within the day 4 specimens. Ki67 positive nuclei showed a prominent increase in the group on days 4 and 7. Green Fluorescent Protein (GFP) positivity also revealed cell movement but was slightly slow compared to Ki67. It indicated that restoration of mechanism seemed conspicuous by osteoclasts and macrophages from bone-marrow-derived cells for the periodontal ligament at the furcation area. It was suggested that the remodeling of periodontal ligament with cell acceleration was evoked from the experiment for the group on day 4 and after day 7. Periodontal ligament at the furcation area of the molar teeth in this experimental model recovered using the cells in situ and the bone-marrow-derived cells.

Esthetic treatment of a periodontal patient with prefabricated composite veneers and fiber-reinforced composite: clinical considerations and technique

The advances in periodontal therapy and the clinical success of adhesive dentistry have changed the way dentists treat periodontal patients. As more teeth are saved, the demand for functional and esthetic restoration of periodontally involved teeth grows. Once, these teeth were restored with full-coverage splinted restorations, whereas today, adhesive techniques provide less invasive and less complicated treatment options. This paper presents a novel adhesive combination of fiber-reinforced composite and prefabricated composite veneers to restore function and esthetics in a periodontal patient with severe bone and attachment loss. After successful completion of the periodontal treatment, fiber-reinforced composite has been bonded to the buccal surface of the maxillary anterior teeth in order to control teeth mobility. At the same appointment, prefabricated composite veneers have been bonded to the splinted teeth in order to restore esthetics. The final result shows full integration of contemporary adhesive techniques for single-appointment, minimally invasive treatment of a periodontal patient.

CLINICAL SIGNIFICANCE

This paper describes the use of fiber-reinforced composite and prefabricated composite veneers for the treatment of severe periodontal patients with a minimally invasive, single-appointment technique.

Periodontal parameters in different dentofacial vertical patterns

OBJECTIVE

To assess periodontal parameters in a Jordanian population in individuals with three different facial types.

MATERIALS AND METHODS

Forty-five dental students (ages 20-26 years) with short, average, and long face heights were divided into three equal groups. The plaque index, gingival index, gingival thickness, width of keratinized gingiva, and width of attached gingiva were measured in each group. Occlusal factors, including the dynamic occlusion and the presence or absence of premature contacts were recorded. Differences among the three groups were assessed using Student's t-test, chi-square test, and analysis of variance (ANOVA) test.

RESULTS

No differences were present in the plaque index, gingival index, gingival attachment, width of attached and keratinized gingiva and gingival thickness between the subjects in the three groups studied. None of the subjects in the long face group had canine guidance dynamic occlusion.

CONCLUSIONS

There were no differences in the periodontal parameters between the different dentofacial vertical patterns, but there was a difference in the canine guidance dynamic occlusion.

Favorable Periodontal Regenerative Outcomes From Teeth With Presurgical Mobility: A Retrospective Study

BACKGROUND

The relevance of tooth mobility on periodontal healing is still controversial. The purpose of the present study was to evaluate the effect of presurgical tooth mobility on periodontal regenerative outcomes.

METHODS

The data in this study were derived from three randomized clinical trials which evaluated regenerative procedures. Sixty-four patients with one intraosseous periodontal defect each received one of the following treatments: guided tissue regeneration (GTR) using expanded polytetrafluoroethylene (ePTFE), GTR using a bioabsorbable membrane with or without demineralized freeze-dried bone allograft (DFDBA), or enamel matrix derivative with or without DFDBA. Probing depth (PD), clinical attachment level (CAL), recession (REC), and tooth mobility (TM) were recorded at baseline and 1 year after treatment by a calibrated examiner. The post-surgical follow-up and maintenance periods were designed to optimize plaque control. The teeth were grouped according to their baseline Miller index TM score. The grouping yielded 36 teeth with minimal mobility, score 0; 13 teeth with score 1; and 15 with score 2. The mean changes in PD, CAL and REC from baseline to 1 year were calculated for each group. One-way analysis of variance (ANOVA) was performed to assess differences between the tooth mobility groups considering changes in PD, CAL, and REC at 1 year.

RESULTS

The mean PD reduction from baseline to 1 year for teeth with TM score 0 was 3.67 mm; for TM score 1, 2.81 mm; and for score 2, 3.73 mm. The corresponding values for the gain in CAL were 2.73, 1.96, and 2.36 mm, respectively. According to ANOVA, the probing depth reductions and clinical attachment level gains found in each group were not statistically different, P= 0.218 and P= 0.252, respectively.

CONCLUSION

Within the limitations of this analysis, it can be concluded that interproximal, intraosseous defects of teeth with limited presurgical tooth mobility; i.e., teeth with Miller's Class 1 and 2 mobility, will respond favorably to regenerative therapy.

Periodontal considerations in restorative and implant therapy

The successful integration of periodontal and restorative dentistry for both natural teeth and implants requires knowledge and application of both mechanical and biological principles. In areas of aesthetic concern, an adequate band of attached gingiva can increase patient comfort, reduce the probability of gingival recession following tooth preparation and simplify restorative procedures. While some restorative margins need to be placed at or below the margin of the free gingiva, this should be considered to be a compromise, and margins should not be placed more than 0.5 mm into a healthy gingival sulcus. Approximately 2-3 mm of healthy, natural supra-alveolar tooth surface is needed for attachment of the gingival tissues to the tooth. This dimension is called the biological width. If adequate biological width does not exist, surgical or orthodontic procedures to expose healthy tooth structure are recommended before final restorations are placed. Retraction of soft tissues for impressions is best accomplished with mechanical methods rather than lasers or electrosurgery because of the potentially harmful effects of these devices to the cementum, bone and soft tissues surrounding the teeth. Implants function best and withstand occlusal forces optimally when loaded in a vertical direction. Therefore, planning implant placement is critical for success. Because of increased proprioception, it is suggested that natural teeth be used to guide the occlusion in partially edentulous patients. Cantilevers should be used with caution and with appropriate attention to occlusal forces. While occlusal trauma does not cause periodontal disease, it may contribute to bone loss around teeth and implants. In the opinion of the authors, provisional restorations are an integral part of dental and periodontal therapy. They can be used to establish aesthetic and physiological contours that can be easily cleaned by patients and they can also be used as a guide for any needed surgical tissue modification.

The effect of occlusal discrepancies on periodontitis. II. Relationship of occlusal treatment to the progression of periodontal disease

BACKGROUND

A causal relationship between occlusal discrepancies and periodontal disease has been postulated in the past. However, minimal data are available concerning the effect of treatment of occlusal discrepancies on periodontitis.

METHODS

The records from a private practice limited to periodontics were reviewed to find patients who had complete periodontal examination records, including occlusal analysis, that were recorded at least 1 year apart. Patients who fit these criteria were divided into a group that had none of the recommended treatment (untreated n = 30), those who had only non-surgical treatment (partially treated n = 18), and a control group that had completed all recommended treatment (surgically treated n = 41). The data for each tooth of each patient, including occlusal status, were placed in a database and analyzed using the generalized estimating equations method.

RESULTS

Worsening in overall clinical condition, as measured by worsening in prognosis, indicated that teeth with no initial occlusal discrepancies and teeth with treated initial occlusal discrepancies were only about 60% as likely to worsen in overall clinical condition over time compared to teeth with untreated occlusal discrepancies. Teeth with untreated occlusal discrepancies were also shown to have a significantly greater increase in probing depth per year than either teeth without initial occlusal discrepancies or teeth with treated initial occlusal discrepancies (P < 0.001). In addition, teeth with untreated occlusal discrepancies had a significant increase in probing depth per year (P < 0.001), whereas teeth without initial occlusal discrepancies and teeth with treated initial occlusal discrepancies had no significant increase in probing depth per year (P > 0.05).

CONCLUSIONS

This study provides strong evidence of an association between untreated occlusal discrepancies and the progression of periodontal disease. In addition, this study shows that occlusal treatment significantly reduces the progression of periodontal disease over time and can be an important adjunct therapy in the comprehensive treatment of periodontal disease.

The effect of occlusal discrepancies on periodontitis. I. Relationship of initial occlusal discrepancies to initial clinical parameters

BACKGROUND

A causal relationship between occlusal discrepancies and periodontal disease has been postulated in the past. However, animal studies and clinical studies have not been able to clearly demonstrate or rule out this potential relationship.

METHODS

The records from a private practice limited to periodontics were reviewed to find patients who had complete periodontal examination records, including occlusal analysis, that were recorded at least 1 year apart. Patients who fit these criteria were divided into a group who had none of the recommended treatment (untreated n = 30), those that had only nonsurgical treatment (partially treated n = 18), and a control group that had complete all recommended treatment (surgically treated n = 41). The data for each tooth of each patient, including occlusal status, were placed in a database and analyzed using the generalized estimating equations (GEE) method to test for associations between initial occlusal discrepancies and various initial clinical parameters while adjusting for significant confounders.

RESULTS

Teeth with initial occlusal discrepancies were found to have significantly deeper initial probing depths (P < 0.0001), significantly worse prognoses (P < 0.0001), and significantly worse mobility than teeth without initial occlusal discrepancies. In addition, this association between initial occlusal discrepancies and initial periodontal condition was found to hold for various subsets considered as well, including posterior teeth only and when only patients with good oral hygiene were considered.

CONCLUSIONS

This study indicates that there is a strong association between initial occlusal discrepancies and various clinical parameters indicative of periodontal disease. Based on adjustments made for other known risk factors for periodontal disease, such as smoking, poor oral hygiene, etc., this study provides some evidence that occlusal discrepancy is an independent risk factor contributing to periodontal disease.

Occlusal trauma: effect and impact on the periodontium

This focused review is limited to a number of investigations in an attempt to specifically address the histological and clinical effects of excessive occlusal forces on the teeth and periodontium and to provide a basis of classification for this interaction. This review does not include the effects of occlusal forces on dental implants or dental prostheses/appliances.

The effects of extracellular citric acid acidosis on the viability, cellular adhesion capacity and protein synthesis of cultured human gingival fibroblasts

Root surface demineralization is widely used as an adjunct to periodontal treatment. To clarify the influence of citric acid root conditioning on periodontal wound healing, the effects of citric acid and associated extracellular acidosis on the viability (MTT assay), attachment and protein synthesis ([3H]-proline incorporation into trichloroacetic acid-precipitated proteins) of human gingival fibroblasts (GF) were investigated. A concentration of 47.6 mmol/L of citric acid (pH 2.3) in water led to total cell death within three minutes of incubation. Media containing 23.8 mmol/L and 47.6 mmol/L of citric acid exerted strong cytotoxicity (47 to 90 per cent of cell death) and inhibited protein synthesis (IC50 = 0.28 per cent) of GF within three hours of incubation. Incubation of cells in a medium containing 11.9 mmol/L of citric acid also suppressed the attachment and spreading of fibroblasts on culture plates and Type I collagen, with 58 per cent and 22 per cent of inhibition, respectively. Culture medium supplemented with 11.9, 23.8 and 47.6 mmol/L of citric acid also led to extracellular acidosis by decreasing the pH value from 7.5 to 6.3, 5.2 and 3.8, respectively. In addition, it was confirmed that the toxic effect of media containing citric acid was due to their acidity rather than the citrate content. Most of the citric acid-induced cell death could be prevented by adjusting the pH value of the culture medium to pH 7.5. Sodium citrate, at a concentration of 47.6 mmol/L, also exerted little cytotoxicity. The results suggested that toxicity of citric acid in specific stages of the healing process must be considered prior to its clinical application. Careful management of citric acid in order to avoid contact with tissue or the development of other demineralizing agents is important in enhancing periodontal wound healing.

Tooth mobility and periodontal disease

Tooth mobility (TM) is an important feature of periodontal disease. This is evidenced by the large number of devices and methods of TM assessment that have been developed and tested. TM had been considered and investigated as an indirect measure of the functional condition of the periodontium as well as possible aggravating co-factor for periodontal disease.

Correlated characteristics of the jaws: association between torus mandibularis and marginal alveolar bone height

The factor marginal alveolar bone height and torus mandibularis (TM) were studied in 2 groups of dentate patients more than 20 years of age, altogether 571 individuals. Subgroups possessing TM had the higher prevalence of unimpaired bone height as compared with those without the trait (P less than 0.001). Different environmental factors considered, such as food habits, exposure to infection, oral hygiene habits, bruxism, access to professional dental care, and habits as to seeking dental treatment, did not seem to account for or to have any influence on the observed phenotypic correlation between TM and more favorable bone height. It was therefore suggested that TM and marginal bone seem to be influenced by common pleiotropic genes. It is hypothesized that future disclosure of the loci that regulate the capacity to develop TM at the same time may throw some light on the genetic contribution and mechanisms that tend to make the marginal alveolar bone more resistant to destructive agents.

Clinical diagnosis of trauma from occlusion and its relation with severity of periodontitis

The purpose of the present study was to determine the reliability of several selected signs of trauma from occlusion and their relations with severity of periodontitis. 32 moderate to advanced chronic periodontitis patients participated in the study. All teeth present were evaluated for various abnormal occlusal contacts, signs of trauma from occlusion, and the severity of periodontitis. Standardized periapical radiographs were also taken for each tooth. The results demonstrated that: (1) no significant difference occurred in probing pocket depth (PD), clinical attachment loss (AL), or percentage of alveolar bone height (BH) between teeth with and without various abnormal occlusal contacts, i.e., premature contacts in centric relation occlusion, non-working contacts in lateral excursions, premature contacts of anterior teeth or posterior protrusive tooth contacts; (2) teeth with either significant mobility, functional mobility, or radiographically widened periodontal ligament space (PDLS) had deeper PD, more AL and lower BH than teeth without these signs, while teeth with pronounced wear or radiographically thickened lamina dura had less AL than teeth without these findings; (3) 2 combined indices, i.e., the trauma from occlusion index (TOI) and the adaptability index (AI), were proposed for the identification of occlusal trauma and the response of periodontium to excessive biting forces in heavy function, respectively; TOI-positive teeth exhibit deeper PD, more AL and less osseous support than TOI-negative teeth; however, AI-positive teeth had less AL and more osseous support than AI-negative teeth; (4) with identical attachment level, TOI-positive teeth had less osseous support than TOI-negative teeth while the magnitude of difference became greater with an increase of attachment loss.

Severe vertical overlap: a modified method of treatment

Severe vertical overlap may predispose the patient to abnormal function, improper mastication, excessive stress, and functional problems such as bruxing, clenching, and craniomandibular disorders. This report describes the establishment of a new occlusal relationship by using the potential of posterior tooth eruption with the Hawley bite plane or the canine platform method. It was used in patients with a full complement of teeth or with some missing teeth. Patients treated by either the Hawley bite plane or the canine platform demonstrate a stable and long-lasting new occlusal relationship. The method described is efficient, inexpensive, and convenient to the patient.