Lack of significance of increased tooth mobility in experimental periodontitis

Ozone in Patients with Periodontitis: A Clinical and Microbiological Study

The purpose of this article was to assess the effectiveness of ozone therapy as an adjunct to mechanical therapy in periodontitis patients. Thirty-two patients diagnosed with generalized periodontitis were selected, with a total of 655 teeth examined. Each patient’s mouth was divided into four quadrants (the split-mouth model) to be randomly treated with four sessions of gaseous ozone or air. The following clinical variables were recorded: the gingival index, the periodontal clinical attachment loss, the Miller’s mobility index and the clinical improvements, as assessed through the visual analog scale (VAS). In addition, the microorganisms were qualitatively compared. After four weeks of treatment, the teeth of the ozone-treated quadrants showed statistically significant reductions in the gingival index and an improvement in the clinical attachment (p < 0.0001). The same treatment also significantly improved mobility by between 70% and 86% compared to the control group (p < 0.0001). Statistically significant differences were also recorded for the VAS (p < 0.0001). In the qualitative study of the subgingival flora, significant differences were observed (p < 0.0001). The overall results of this trial support the view that ozone treatment is effective and well tolerated in cases of generalized chronic periodontitis.

Interdisciplinary interface between fixed prosthodontics and periodontics

Although periodontal factors do not usually have a direct effect on the survival of a fixed prosthesis, harmony between the prosthesis and the periodontium is critical otherwise esthetics, the longevity of the prosthesis and the periodontium will be compromised. A close interdisciplinary relationship between periodontics and prosthodontics is therefore necessary to avoid an unsatisfactory treatment outcome, requiring extensive and expensive retreatment. The design of the prosthesis, the number and quality of the abutment teeth, the preparation and the pontic, the occlusion and the material need to be considered when planning prosthodontic treatment. The location of the preparation margin and the contour and emergence profile of the prosthesis will influence the response of the gingival tissues to the prosthesis. Pontic design and cleansibility also contribute to the response of the gingival tissues as well as to the clinical and esthetic outcome. Even an optimal pontic design will not prevent inflammation of the mucosa adjacent to the pontic if pontic hygiene is not maintained by removal of plaque. Case selection and the patients' ability to carry out adequate oral hygiene are therefore essential for longevity of the prosthesis, and regular reviews provide an opportunity for early detection and treatment of failures.

Traditional or regenerative periodontal surgery?-a comparison of the publications between two periodontal journals over time

OBJECTIVES

The objective is to compare the amount and content of publications regarding traditional or regenerative periodontal surgery in the years 1982/1983 and 2012/2013 in two leading periodontal journals of North America and Europe.

MATERIAL AND METHODS

The search was carried out in the Journal of Periodontology and Journal of Clinical Periodontology. Four reviewers screened the articles and allocated the topics with respect to periodontal surgery. The distribution of articles with respect to traditional or regenerative periodontal surgery was then compared between the journals and the respective time periods.

RESULTS

Out of 1084 screened articles, 145 articles were included. Articles with periodontal surgery content amounted to 18% for the first time period and to 11% for the second time period. In the years 1982/1983, 7% of articles in the Journal of Periodontology and 8% in the Journal of Clinical Periodontology referred to traditional periodontal surgery, while 8% (Journal of Periodontology) and 5% (Journal of Clinical Periodontology) examined regenerative periodontal surgery. The distribution changed 30 years later, with 1% (Journal of Periodontology) and 3% (Journal of Clinical Periodontology) traditional periodontal surgery and 7% and 6% regenerative periodontal surgery content.

CONCLUSION

While the clinical need for traditional periodontal surgery remained, research in this important field decreased. Publications rather tended to focus on adjunctive regenerative measures.

CLINICAL RELEVANCE

Periodontal surgery with adjunctive regenerative measures is an established and well-documented clinical procedure. However, with respect to the dominance of horizontal bone loss in periodontally diseased patients, there is a need for ongoing research with focus on traditional periodontal surgery.

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.

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.

Intentional passive eruption combined with scaling and root planing of teeth with moderate chronic periodontitis and traumatic occlusion

PURPOSE

The aim of this clinical trial was to explore the impact of intentional passive eruption (IPE) using occlusal reduction on the periodontal parameters of teeth with moderate chronic periodontitis and traumatic occlusion.

METHODS

This study was performed on 40 teeth from 16 subjects. At baseline, 4 weeks after initial periodontal treatment, and 6 months after IPE, clinical and radiographic examinations were performed. The 20 teeth in the test group underwent IPE using occlusal reduction, whereas the 20 control teeth did not undergone occlusal reduction.

RESULTS

All the periodontal parameters were improved by the initial periodontal treatment. The teeth in the test group showed a significantly greater decrease in pocket depth, tooth mobility, and marginal bone loss than did the control group (P<0.05), but there were no significant changes in the attachment level. Significantly greater improvements in all the parameters were observed in the test group after 6 months of IPE compared to 4 weeks after the initial periodontal treatment (P<0.05).

CONCLUSIONS

Within the limits of this study, performing initial periodontal therapy combined with IPE using occlusal reduction was shown to be very simple and effective. Moreover, IPE would be helpful in improving periodontal parameters.

Maxillary rehabilitation of periodontally compromised patients with extensive one-piece fixed prostheses supported by natural teeth: a retrospective longitudinal study

Objectives

Oral health-related quality of life is a relatively new but rapidly growing concept in dentistry. It is an aspect of dental health addressing the patient’s perception of whether his/her current oral health status has an impact upon his/her actual quality of life. Dentine hypersensitivity (DHS), which is a common condition of transient tooth pain associated with a variety of exogenous stimuli, may disturb the patient during eating, drinking, toothbrushing and sometimes even breathing. The resulting restrictions on everyday activities can have an important effect on the patient’s quality of life. The aims of this paper were to consider the concept of oral health-related quality of life and to review and discuss the literature on oral health-related quality of life and DHS.

Material and methods

A PubMed literature research was conducted using the terms (“dentin sensitivity” [MeSH Terms] OR (“dentin” [All Fields] AND “sensitivity” [All Fields]) OR “dentin sensitivity” [All Fields]) AND ((“oral health” [MeSH Terms] OR (“oral” [All Fields] AND “health” [All Fields]) OR “oral health” [All Fields]) AND related [All Fields] AND (“quality of life” [MeSH Terms] OR (“quality” [All Fields] AND “life” [All Fields]) OR “quality of life” [All Fields])). Furthermore, a manual search was carried out. Any relevant work published presenting pertinent information about the described issue was considered for inclusion in the review.

Results

The combination of the search terms resulted in a list of only three titles. The few published studies convincingly demonstrated that oral health-related quality of life is negatively affected in patients suffering from DHS.

Conclusions

Patients with sensitive teeth report substantial oral health-related quality of life (OHRQoL) impairment. Nevertheless, knowledge about the influence of DHS on oral health-related quality of life is incomplete and, therefore, needs further research.

Clinical relevance

Oral diseases can lead to physical, psychological and social disability. This paper shows that DHS can have a negative impact on the patients’ OHRQoL.

Salvaging a tooth with a deep palatogingival groove: an endo-perio treatment – a case report

AIM

To describe the diagnosis and management of tooth 22 with a necrotic pulp and severe periodontal destruction associated with a deep palatogingival groove extending to the root apex.

SUMMARY

Palatogingival grooves are uncommon in maxillary lateral incisors, but when present may contribute to the pathogenesis of periodontal and endodontic lesions. In the present case, the prognosis was considered poor, as the patient presented with a deep probing defect, advanced bone loss and grade III mobility of tooth 22. Root canal treatment was performed, followed by periodontal surgery, during which the groove was conditioned and sealed with conventional glass-ionomer cement and the osseous defect filled with indigenously prepared hydroxyapatite. The 18 month post-operative follow up showed substantial resolution of the osseous defect with gain in attachment and decreased tooth mobility.

KEY LEARNING POINTS

Teeth with deep palatogingival grooves may be significantly compromised with severe periodontal and periapical bone loss. Following thorough evaluation, the careful application of endodontic and periodontal surgical procedures may restore satisfactory function.

Ante's (1926) law revisited: a systematic review on survival rates and complications of fixed dental prostheses (FDPs) on severely reduced periodontal tissue support

BACKGROUND

In subjects suffering from generalized severe periodontitis, only a few teeth may be treated and used as abutments for fixed dental prostheses (FDPs).

OBJECTIVE

To systematically review the impact of severely reduced, but healthy periodontal tissue support on the survival rate and complications of FDPs after a mean follow-up time of at least 5 years.

SEARCH STRATEGY

Publications considered for inclusion were searched in MEDLINE (PubMed) and relevant journals were hand searched. The search was performed in duplicate and was limited to human studies published in the dental literature from 1966 up to and including September 2006. Only publications in English, in peer-reviewed journals, were considered. Abstracts were excluded.

SELECTION CRITERIA

Prospective and retrospective cohort studies were included. The primary outcome measure included survival rates of FDPs and abutment teeth, whereas biological and technical complications of FDPs and abutment teeth represented secondary outcome measures.

DATA ANALYSIS

Summary estimates of survival rates and of biological and technical complications were calculated after 5 and 10 years.

RESULTS

The search provided 860 titles of which six publications were included. A total of 579 FDPs were incorporated and followed up to 25 years. Meta-analysis yielded an estimated FDP survival rate of 96.4% [95% confidence interval (95% CI): 94.6-97.6%] after five and of 92.9% (95% CI: 89.5-95.3%) after 10 years, respectively. After 10 years, the estimated rate of abutment teeth without endodontic complications amounted to 93% (95% CI: 62.6-98.9%). The 10-year estimated rate of caries-free abutment teeth was 98.1% (95% CI: 88.2-99.7%). FDPs without loss of retention were estimated to occur in 95.4% (95% CI: 92.6-97.2%) of cases after 10 years.

CONCLUSIONS

These results showed that (i) masticatory function could be established and maintained in subjects receiving FDPs on abutment teeth with severely reduced but healthy periodontal tissue support and (ii) FDPs survival rates compared favourably with those of FDPs incorporated in subjects without severely periodontally compromised dentitions.

Cementum Crack Formation by Repeated Loading In Vitro

BACKGROUND

In this study, the hypothesis was adopted that fatigue destruction may develop on the cementum of the root surface because of the repeated occlusal stresses loaded on the tooth as in the case of prolonged occlusal trauma. The purpose of this study is to clarify whether cemental fatigue destruction occurs when repeated stresses are loaded on the occlusal surface of a tooth.

METHODS

The teeth used were five human mandible premolars from individuals 14 to 22 years of age. The teeth were freshly extracted in orthodontic treatment. They were free of decay and fillings, and their roots were straight. One half of the root was embedded in cold curing acrylic resin, and a compressive load of 5.0 kgf was repeatedly applied along the tooth axis in water 1 million times with a speed of one time per second. Changes in the tooth surface were observed by taking photographs with a stereoscopic microscope and a digital camera after every 100,000 loadings. Cracks were dyed with 2% methylene blue solution, and crack areas were measured using gray-scaled and binary-processed photographs. Data were analyzed using image analysis software.

RESULTS

It was confirmed that cracks significantly developed on the buccal, mesial, and distal surfaces but not on the lingual surface; crack areas showed a tendency to significantly increase after 500,000 loadings; extension of the crack from the cemento-enamel junction to the root apex increased with time, and the average extension was 0.67 +/- 0.12 mm after 1 million loadings.

CONCLUSION

This study revealed that cementum cracks developed in the cervix by repeated loadings and extended toward the root apex with time, suggesting that repeated stresses by occlusion or strong stresses such as by bruxism may trigger the development of site-specific attachment loss, which is one of the potential factors inducing periodontal diseases.

Using a Delphi Panel to Survey Criteria for Successful Periodontal Therapy in Anterior Teeth

BACKGROUND

Valuable decision making for periodontal treatment success in situations where there is ambiguous or conflicting information was previously reported using a consensus building method, the Delphi survey, for posterior teeth with chronic periodontitis. This study focuses on outcome measures relevant in assessing therapy of anterior teeth with chronic periodontitis.

METHODS

The Delphi panelists were the same American periodontists who participated in the previous Delphi survey evaluating successful therapy in posterior teeth. In this study, panelists determined the level of importance of attachment level, probing depth, mobility, plaque, inflammation, esthetics, pain, and patient satisfaction following periodontal treatment of a single tooth or multiple anterior teeth in a patient with severe chronic periodontitis. The panelists were questioned concerning the relative importance of each outcome measure, a minimally acceptable level considered necessary for success for each outcome measure, and the length of time required for these outcome measures to remain stable.

RESULTS

The 35 panelists considered the control of pain, esthetics, and patient satisfaction to be "extremely important" outcome measures for successful periodontal treatment of single or multiple teeth. Attachment levels, probing depths, plaque levels, degree of inflammation, and mobility (for multiple teeth) were considered to be "very important" outcomes. The minimally acceptable reduction in probing depths following 1 year of treatment was 2 mm; whereas 2 mm of attachment gain was considered necessary for successful treatment. The panel also found a Miller degree I mobility as an acceptable outcome for clinical success. Finally, the panel agreed that the 1-year results of treatment should remain stable for a minimum of 5 years.

CONCLUSIONS

The Delphi technique proved a practical instrument to transform expert opinion into a group consensus for relevant periodontal outcome measures. Absence of pain, esthetics, and patient satisfaction were outcome measures considered "extremely important" for successful therapy. Although panelists considered attachment loss, probing depths, and mobility somewhat less important outcomes, they wanted an attachment gain of 2 mm and would accept a degree I mobility as long as outcomes remained stable for 5 years. These data suggest that minimal standards for successful therapy of anterior teeth can be established among periodontal practitioners.

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.

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.

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.

Progression of periodontal tissue destruction at splinted/non-splinted teeth. An experimental study in the dog

The aim of the present investigation was to study whether splinting, i.e., immobilisation of teeth, may interfere with the rate of periodontal tissue destruction that can be accomplished by ligature placement and plaque accumulation, 5, 1-year-old, beagle dogs were included in the experiment. The mandibular 2nd and 3rd premolars and the 1st molar on both sides of the mandible were extracted. 2 titanium implants were installed in the sites of 3P and 1M, i.e., in the right quadrant of the mandible. 3 months later, abutment connection was performed and a fixed, gold splint, connecting the tooth and the implants, was inserted. The non-resilient splint was cemented in place on Day 0 and 4P was hereby immobilized. In each dog, the contralateral fourth premolar (P4) served as the non-splinted control tooth. Experimental periodontal tissue breakdown was initiated by placing cotton floss ligatures around the neck of 4P and P4 and by allowing the animals to accumulate plaque and calculus. Once every month, new ligatures were placed at the level of the receding gingival margin. The experiment was terminated on Day 180. Radiographs of 4P and P4 were obtained and biopsies sampled. The results of the measurements, made in the radiographs and the histological sections, disclosed that the splinting of the experimental teeth, failed to prevent or retard apical downgrowth of plaque and associated attachment loss. It was concluded that increased tooth mobility, within the limits of the present experiment, obviously did not establish conditions which favoured an enhanced destruction of the periodontal tissues in the beagle dog model.

Probing pocket depth at mobile/nonmobile teeth

The aim of the present investigation was to study the influence of an increased tooth mobility on the resistance offered by the periodontal tissues to probing. 6 beagle dogs were used. At the start of the experiment, the animals had clean teeth and normal gingival and periodontal conditions. In each dog, a device was installed in the lower left jaw quadrant to expose the third premolar (P3) to jiggling forces which would enhance the mobility of this "test" tooth. The contralateral tooth served as the non-jiggled control. During the 3 months of experimentation, the teeth of the dogs were cleaned on a regular basis. Clinical examinations including tooth mobility measurements were performed on days 0 and 90. After the examination on Day 90, a probe was inserted in the buccal "pocket" of the mesial root of 3P and P3. The probe was retained with composite. Biopsies including the test or control tooth with adjacent buccal periodontal tissues were harvested, fixed and decalcified. Each biopsy was divided in one mesial and one distal portion (root). The distal portion was embedded in Epon, sectioned and stained in PAS and toluidine blue, while the mesial portion, following probe removal was embedded in paraffin, sectioned and stained in hematoxylin-eosin. The sections were exposed to histometric and morphometric measurements. The findings demonstrated that tissue alterations which occur at mobile teeth may reduce the resistance offered by the periodontal tissues to clinical probing. Such alterations include (i) reduced height of the alveolar bone, (ii) reduced amount of collagen, and increased vascularity in the enlarged supracrestal connective tissue.

A randomized trial of occlusal adjustment in the treatment of periodontitis patients

The purpose of the randomized clinical trial was to test; (1) the influence of occlusal adjustment (OA) in association with periodontal therapy on attachment levels, pocket depth, and tooth mobility, (2) whether OA was of greater significance in non-surgically treated periodontal defects, and (3) whether initial tooth mobility or disease severity had an affect on post-treatment attachment levels following OA. After hygienic-phase therapy, 50 patients received OA/No OA according to random assignment; 22 patients received an OA and 28 were not adjusted. 2 months after OA, either modified Widman flap surgery or scaling and root planing by a periodontist were done according to random assignment within each patient in a split-mouth design. Following active treatment patients were maintained with prophylaxis done every 3 months and scored annually. For the analysis of this two-year data, a repeated measures analysis of variance was performed using attachment level change and pocket depths as outcome indicators. There was significantly greater gain of clinical periodontal attachment in patients who received an OA compared to those who did not. Both the surgically and non-surgically treated sides of the mouth responded similarly to OA. There was no affect of OA on the response in pocket depth, nor did initial tooth mobility or initial periodontal disease severity influence the response to OA.

Effects of destructive periodontitis, induced by diet, on the mechanical properties of the periodontal ligament of the mandibular first molar in golden hamsters

To examine progressive changes in the mechanical properties of the periodontal ligament in the hamster mandibular first molar with experimental periodontitis--induced by feeding a high-carbohydrate diet--load-deformation curves obtained by extracting the tooth from its socket in the dissected jaw were analyzed. The maximum shear load, elastic stiffness and failure energy in shear in the experimental groups decreased significantly during the experimental period. On the other hand, significant differences in the maximum deformation were not found between the experimental and the relevant control groups. Radiographic and histological observations showed that the alveolar bone loss and destruction of the periodontal tissues occurred at the cervical region of the tooth in the experimental animals at 8 and 12 weeks after the start of the experiment. It is suggested that the reduction of the mechanical strength of the periodontal ligament in the experimental animals may be due to the alveolar bone loss, destruction of the periodontal tissues at the cervical region--particularly on the lingual aspect--followed by a decrease in the surface area of the ligament. It is also suggested that degenerative changes in the remaining periodontal ligament occurred in hamsters with periodontal disease, causing a reduction in the mechanical strength of the ligament.

Patterns of initial tooth displacements associated with various root lengths and alveolar bone heights

The present study was designed to investigate the nature of initial tooth displacements associated with varying root lengths and alveolar bone heights. A three-dimensional model of the upper central incisor was developed for the finite element analysis. Tooth displacements were determined at various levels of the tooth and the apicogingival levels of the center of resistance and centers of rotation were calculated. The results showed that moment-to-force values at the bracket level for translation of a tooth decreased with shorter root length and increased with lower alveolar bone height. In addition, apicogingival levels of the center of resistance shifted more gingivally to the cervix, or the alveolar crest with a shorter root. Alveolar bone loss also shifted the center of resistance toward the alveolar crest, whereas its position was more apical relative to the alveolar bone heights exhibited very slight changes in both cases. The centers of rotation from a single force varied substantially with a short root and alveolar bone loss. However, the relative distances of the centers of rotation from the alveolar crest in comparison with the alveolar bone heights were constant at 0.4 mm, with variations in the root length and alveolar bone height. Because this study showed that root length and alveolar bone height affect the patterns of initial tooth displacements both in the center of resistance and the centers of rotation and also in the amount of displacement, forces applied during orthodontic treatment should take into consideration the anatomic variations in the root length and alveolar bone height so as to produce optimal and desired tooth movement.

The combined effects of plaque and physical stress on periodontal tissues

Experiments have been performed in beagle dogs in attempts to evaluate the effect of orthodontic- and jiggling-type trauma on the supporting structures of premolars. The results reported have unanimously demonstrated that in situations where orthodontic or jiggling forces were inflicted on teeth with a normal periodontium, or on teeth with overt signs of gingivitis, the periodontal ligament tissue reacted by transitory signs of inflammation. These phenomena occurred without a concomitant loss of connective tissue attachment and development of pathologically deepened periodontal pockets. If the jiggling trauma was inflicted on teeth with an ongoing plaque-associated, destructive periodontitis, the resulting inflammatory reactions caused enhanced loss of attachment and angular bony defects. Furthermore, orthodontic tilting movements of teeth (intrusion) in a plaque-infected dentition may shift a supragingivally located plaque into a subgingival position resulting in periodontal tissue breakdown.