Enamel dictates whole tooth deformation: a finite element model study validated by a metrology method.

In order to understand whole tooth behavior under load the biomechanical role of enamel and dentin has to be determined. We approach this question by comparing the deformation pattern and stiffness of intact teeth under load with the deformation pattern and stiffness of the same teeth after the enamel has been mechanically compromised by introducing a defect. FE models of intact human premolars, based on high resolution micro-CT scans, were generated and validated by in vitro electronic speckle pattern interferometry (ESPI) experiments. Once a valid FE model was established, we exploit the flexibility of the FE model to gain more insight into whole tooth function. Results show that the enamel cap is an intrinsically stiff biological structure and its morphology dictates the way a whole tooth will mechanically behave under load. The mechanical properties of the enamel cap were sufficient to mechanically maintain almost its entire stiffness function under load even when a small defect (cavity simulating caries) was introduced into its structure and breached the crown integrity. We conclude that for the most part, that enamel and not dentin dictates the mechanical behavior of the whole tooth.

Fracture resistance of endodontically treated teeth restored with combined composite-amalgam restorations.

OBJECTIVE: To evaluate the resistance to fracture of endodontically treated teeth restored with combined composite-amalgam restorations in comparison to all-amalgam restorations. METHOD AND MATERIALS: Forty-eight human premolar teeth were equally divided into 4 groups. Mesio-occlusodistal (MOD) cavities were prepared in 3 groups, and in the fourth group, a modified MOD preparation was designed with an additional buccolingual groove. All teeth were endodontically treated and restored using 1 of several restorative modalities: all amalgam (AM), all amalgam plus dentin adhesive (ADA), amalgam plus dentin adhesive plus composite resin (ADAC), and amalgam plus dentin adhesive plus composite resin with a modified preparation design (ADACM). Specimens were tested in a universal testing machine (Instron). The load (in kilonewtons) at fracture was recorded and statistically analyzed using a Bonferroni one-way statistical analysis (significance: P

Dental and oral trauma during childhood and adolescence in Israel: occurrence, causes, and outcomes.

The occurrence and causes of oral and dental injuries in a young Israeli population during childhood and adolescence were evaluated, as well as participants' awareness of using protective devices, such as mouth guards, during sporting activities. The survey consisted of 427 young adults, aged 18-21 years. A questionnaire was distributed relating to past oral and dental injuries over their lifetime; type of sporting activity practiced, specifying time, place and cause of injury; and use and awareness of protective devices. Participants who reported to be injured were asked to report the type of their injury, treatment provided, and satisfaction with the results. The total number of dental and oral injuries was 133, affecting 31.1% of the participants, in which 72 (16.9%) suffered dental injuries, mostly because of falls (64%), followed by sporting activities (23.2%), street-fights (7.2%), and car accidents (5.6%). Injuries occurred at school in 36.5% of cases and at home in 23.8% of cases. The most frequently reported injury was laceration (47.3%) followed by tooth fracture (41.9%). Of the 427 participants, 239 (56%) were active in at least one type of sport. Only 22.6% were aware of protective devices, e.g. mouth guards, and only 2.8% actually used these devices. These results show the high risk of potential dental and oral injury during childhood and adolescence, a lack of knowledge regarding the benefits of mouth guards and their limited use. Increased awareness of protective measures and devices, and their actual use should be encouraged with public health education.

Cross-sectional radiographic survey of amalgam and resin-based composite posterior restorations.

OBJECTIVE: To compare the failure rate of posterior interproximal amalgam restorations to resin-based composite restorations in a random young adult population. METHOD AND MATERIALS: Bilateral bitewing radiographs of 459 young adults were screened. A total of 14,140 interproximal surfaces were examined, recorded, and statistically analyzed. Rate of failure was determined by the number of restorations with radiographic evidence of secondary caries and/or overhanging margins. RESULTS: Of the 650 restored interproximal surfaces (5% of all clearly demarcated interproximal surfaces), 86 (13%) demonstrated distinct interproximal secondary caries and 22 (3%) had overhanging margins. Of the 557 amalgam and 93 resin-based composite interproximal restorations, secondary caries were shown in 46 (8%) and 40 (43%), respectively, and overhanging margins in 21 (4%) and only 1 (1%), respectively. Generally, when secondary caries and overhanging margins were considered, the failure rate of amalgam and resin-based composite interproximal restorations was 12% and 44%, respectively. CONCLUSIONS: Higher failure rates were observed in resin-based composite restorations than in amalgam restorations. Secondary caries was the main reason for failure. Overhanging margins were not a primary factor in restoration failure. The vast use of posterior interproximal resin-based composite restorations should be reconsidered, and their limited long-term performance should be kept in mind.

Patients' satisfaction with dental esthetics.

BACKGROUND: Esthetics has become an important issue in modern society, as it seems to define one's character. In the past, functional demands were the main consideration in dental treatment. Today, with the decrease in caries prevalence, the focus has shifted toward dental esthetics. The authors conducted a study to evaluate the factors influencing patients' satisfaction with their dental appearance and with the results of esthetic treatment. METHODS: The authors surveyed a population of 407 adults (mean age, 21 years). They distributed a questionnaire regarding satisfaction with current dental esthetics and previous esthetic treatments. RESULTS: Of the 407 subjects, 152 (37.3 percent) were dissatisfied with their dental appearance. Tooth color was the primary reason for dissatisfaction (133 [89.3 percent] of 149 subjects), followed by poor tooth alignment (36 [23.7 percent] of 152 subjects), although 110 (27 percent) of the 407 subjects had received orthodontic treatment. The authors found no correlation between patients' satisfaction with their dental appearance and having undergone any procedure to whiten their teeth. Nevertheless, 134 (88.2 percent) of the dissatisfied subjects reported that they would like to undergo this procedure. CONCLUSIONS: Tooth color was a major factor with regard to dental esthetics. Most subjects were interested in improving their appearance and whitening their teeth. CLINICAL IMPLICATIONS: When planning treatment, dentists should take into consideration esthetic objectives in addition to function, structure and biology. This requires the clinician to rely on several disciplines in dentistry to deliver the highest level of dental care, which should lead to a higher level of patient satisfaction.

The clinical effect of amorphous calcium phosphate (ACP) on root surface hypersensitivity.

Dentin hypersensitivity is a transient condition that often resolves with the natural sclerotic obturation of dentin tubules. A method of rapidly forming calcium phosphate compounds within these tubules can mimic sclerosis and lead to rapid reduction in hypersensitivity. Amorphous calcium phosphates (ACP) can be formed in situ by the sequential application of calcium and phosphate solutions. In this clinical study, 30 patients with reported dentin hypersensitivity were randomly assigned to parallel treatment or placebo groups. In the experimental treatment group, ACP was formed by topical application of a 1.5 mol/L aqueous solution of CaCl2 followed by topical application of 1.0 mol/L aqueous K3PO4. The placebo group was treated with a topical application of 1.0 mol/L aqueous solution of KCl followed by topical application of distilled water. Treatments were repeated at the 7-day and 28-day recall appointments. Response to air and tactile stimuli were measured immediately before treatment using a visual analog scale initially on day 1, then on days 7, 28 and 180. The results showed that both the experimental and placebo treatments resulted in a reduction in hypersensitivity at 180 days. However, the ACP treatment group showed a much more rapid reduction in hypersensitivity over time. The change in sensitivity was much more apparent using the air stimulus than the tactile stimulus. These results show that topical placement of ACP can rapidly reduce dentin hypersensitivity.

Dental and oral trauma and mouthguard use during sport activities in Israel.

The purpose of the present study was to evaluate the occurrence of oral and dental injuries in young Israeli population engaged in diverse sport activities. The participants' awareness of the use of protective devices, such as mouthguards, during sport activities was also evaluated. A population of 943 young adults, 95% males and 5% females (ages 18-19), was surveyed. A questionnaire was distributed relating to the type of sport activity practised, past oral and dental injuries over their lifetime, specifying the time and type of sports in which the injury occurred and the use and awareness of the protective devices. Of the total population examined, 850 (90%) were active in at least one type of sport, either as professionals or as amateurs. The analysis included the population that regularly participated in at least one sporting activity. The most commonly practised sports were soccer (54% of all active participants) and basketball (50%). The total number of dental and oral injuries experienced during all sport activities was 229, affecting 27% of the participants of whom 73 (9%) suffered dental injuries. Most dental injuries occurred during the basketball and soccer training sessions and matches reaching 42 and 41% of the total number of injuries, respectively, and affected 7.2 and 6.6% of the basketball and soccer players. Traumatic dental injuries in other sports occurred in less than 7% of the participants in these activities. Only 27% of the participants were aware of the protective devices, such as a mouthguards, and only 3% actually used these devices. These results point to the high risk of potential dental and oral injury during sport activities, the little knowledge about the benefits of using mouthguards and their limited utilization. The importance of public health education to increase the awareness of protective measures and devices and their actual use in Israel is the main focus. It should be a combined duty of dentists and sports physicians and of the coaches to encourage the use of protective devices during training and games.