Effect of mass variation on vibration properties of the tooth in drilling operation.

Dental cavity represent one of the widespread illness of the tooth. Method for treating of the tooth is to drill the cavity and to fill the hole with suitable material. Measurements show that during drilling the tooth vibrates with increasing mass that causes unpleasant feeling for patient. The aim of the paper is to give the theoretical explanation for this phenomena and to give suggestion for vibration elimination. During drilling, mass of the tooth is decreasing and the so called 'reactive force' occurs. Drilling and reactive force cause tooth vibration. The system is modeled as a nonlinear time variable system. An analytical procedure for solving of the equation of vibration is developed. The solution is assumed in the form of the generalized trigonometric function with time variable amplitude and phase. It is obtained that not only the amplitude but also the frequency of tooth vibration in drilling are increased. In addition to reactive force the drilling velocity, diameter of the drill tool and spindle speed affect the vibration level. The appropriate values of these parameters would eliminate or decrease the patient bad feeling.

Unmet oral health needs among persons with intellectual disability.

The aim of this study was to examine the factors affecting oral health status among intellectually disabled individuals in Serbia. The sample population was categorized according to age, sex, living arrangements, general health and the level of intellectual disability (ID). The diagnosis of dental caries was performed using the DMFT/dmft criteria. The oral hygiene and gingival health were assessed with the plaque index (Silness&Löe) and gingival index (Löe&Silness), respectively. Descriptive analysis, step-wise and logistic regression were performed to analyze related influential factors for caries presence, number of extracted teeth, teeth restored, the oral hygiene level and the extent of gingival inflammation. Odds ratios for caries were significantly higher among adult persons with ID, in persons with co-occurring developmental disorders (DDS) and increased with the level of ID. Group with DDS was associated with a 1.6 times greater odds of untreated decay, while the institutionalization was associated with 2.4 times greater odds of untreated decay. Institutionalization and co-occurring disabilities have been found to be significantly associated with a higher probability of developing gingivitis. Targeting oral health services to individuals with ID are encouraged and may help to reduce overall negative effect on oral and general health associated with delayed treatments, chronic dental pain, emergency dental care, tooth loss and advanced periodontal disease.

Risk factors for bleeding after oral surgery in patients who continued using oral anticoagulant therapy.

BACKGROUND: The authors assessed the incidence of postoperative bleeding in patients who were highly anticoagulated and in patients who underwent extensive oral surgical procedures and who continued using oral anticoagulant therapy. METHODS: The authors placed 125 patients receiving anticoagulant therapy into 1 of 3 groups. Group A had 54 patients who were highly anticoagulated (international normalized ratio [INR] ≥ 3.5) in whom up to 3 teeth were extracted. Group B had 60 patients with INR 2.0 to less than 3.5 in whom higher-risk dentoalveolar surgery (extraction of more than 3 teeth or other oral surgery procedure involving raising a mucoperiosteal flap, osteotomy, or biopsy) was performed. Group C had 11 patients whose INR values were 3.5 or higher and who required higher-risk dentoalveolar surgery. Eighty-five healthy participants who underwent surgical procedures similar to those performed in group A and group B were the control group. RESULTS: Two patients in group A (3.7%), 3 in group B (5.0%), and 2 in group C (18.2%) experienced postoperative bleeding. In the control group, a single bleeding event (1.2%) occurred. All cases of hemorrhage were mild and easily controlled using local hemostatic measures. CONCLUSIONS: Dental extractions in patients who are highly anticoagulated (INR, 3.5-4.2), as well as more extensive oral surgical procedures in patients who are therapeutically anticoagulated, can be performed safely without interruption or modification of the therapy. PRACTICAL IMPLICATIONS: Tooth extractions and even more extensive surgical procedures can be performed safely in patients who continue using anticoagulant therapy if proper local hemostatic measures are used and if no other coagulopathies are present.

Examination of the bioelectrical activity of the masticatory muscles during Angle's Class II division 2 therapy with an activator.

BACKGROUND/AIM: The muscles of the orofacial region have great influence on the development of dentition and occlusion formation. It is known that improper function of these muscles is one of the major etiological factors in malocclusion. A correlation between function disorders of orofacial muscle and occlusion disorders has been confirmed, as well as a correlation between the bioelectric activity of the masticatory muscles, recorded by electromyography, and bite force upon maximal voluntary contraction of these muscles. The aim of the study was to analyze the bioelectriacal activity of temporal and masseter muscles. METHODS: The sample consisted of 100 subjects of both sexes, divided into the control group (n = 30) with neutral and complete dental arches, and the study group (n = 70) of patients with distal occlusion. Electromyographic measurement of bioelectric potentials in all the subjects was conducted for the examined muscles in the physiologic rest position, central mandible occlusion, and during maximal voluntary contraction of muscles and saliva swallowing, in Angle Class I and II/2 occlusal relationships, prior to treatment, after one year of the orthodontic treatment and after the treatment with an activator. RESULTS: Comparing the values of the bioelectrical activity in the control and the study group before the treatment, a decreased muscle activity was established in all the three positions in the study group. After the first year of orthodontic treatment the results showed an elevation in the bioelectrical activity in both muscles. After treatment with an activator, the bioelectrical activity in both muscles in the study group was higher than before the treatment, as it is confirmed by a positive highly significant coefficient of correlation. CONCLUSION: In all the three measured positions of the mandible with Angle Class II/2 malocclusion, bioelectrical activity was lowest at baseline and increased during the first year of treatment, and at the end of the treatment it partially reduced close to the approximate values in normal occlusion. Research on electromyographic activity of masticatory muscles is useful in everyday clinical practice, especially in present distinctive skeletal discrepancy before, during and after orthodontic treatment, if on the bases of the results we can evaluate the treatment, but also determine the start and duration of the retention period and retention device type.

Pulp vitality preservation after traumatic dental injuries to permanent teeth.

INTRODUCTION: The pulp vitality preservation after a trauma to permanent teeth is of great importance since dental injuries are common. The aim of our study was to investigate the pulp vitality preservation after tooth injuries. MATERIAL AND METHODS: A retrospective analysis of records of patients with a trauma was performed. The sample consisted of all patients who had been referred to the Department of Dentistry of Vojvodina for a trauma to permanent teeth during the period 2005-2010. We recorded the type of injury, treatment, state of vitality during the first visit and subsequent check-ups. RESULTS: The study included 162 children and adolescents aged 6-18 years having a trauma to 314 permanent teeth. The most frequent type of injuries in permanent teeth was fractures (54.5%), whereas luxation was a less common trauma (45.5%). Though different kinds of traumas have different optimal time for treatment, a period of 24 hours was taken as optimal; hence, 189 teeth were treated in optimal time and 55 complications occurred in them; while 105 complications occurred in 114 teeth which were treated 24 hours after the trauma. A year after the trauma the pulp vitality was preserved in 88 teeth (32%), pulp necrosis and other complications developed in 160 teeth (68%). CONCLUSION: The therapy of pulp vitality preservation in injured teeth was found successful in 32% and unsuccessful in 68% of cases at check-ups over one year.