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Frictional evaluations of dental typodont models using four self-ligating designs and a conventional design.

Abstract: After a previous study using typodonts and three standardized archwire (AW) sizes, the frictional evaluations of four self-ligating brackets were directed toward the optimal AW-bracket system. Four participating manufacturers suggested three AWs, which were a representation of the three stages of orthodontic treatment, to be coupled with their respective self-ligating design. Four replicated typodont models were mounted with a self-ligating design, and a fifth model was mounted with a conventional design that served as a control. The first experiment evaluated the manufacturer-suggested AWs against the respective self-ligating design. Because no third-stage AWs could engage their respective designs, a second experiment was implemented to gain more detailed analyses of the designs. This experiment included any successful manufacturer-suggested AWs from the first experiment against the four self-ligating designs and the control design. All self-ligating designs performed with the efficiency and reproducibility associated with expectations. Specifically, self-ligation outperformed the conventional brackets when coupled with up to 0.020- x 0.020-inch wires. The clearance of the various AW sizes and alloys changed with malocclusion. Furthermore, the parameter that best correlated with drawing forces was the bending stiffness of the AW, which was directly associated with the nominal dimension of each wire. The best AW-bracket system can be selected, when taking into account the stiffness (elastic modulus and size of the AW) along with the amount of malocclusion present, once the treatment plan is determined.

Dental Alloys↗

Analgesic efficacy and tolerability of oxycodone 5 mg/ibuprofen 400 mg compared with those of oxycodone 5 mg/acetaminophen 325 mg and hydrocodone 7.5 mg/acetaminophen 500 mg in patients with moderate to severe postoperative pain: a randomized, double-blind, placebo-controlled, single-dose, parallel-group study in a dental pain model.

BACKGROUND: Combination therapy has been widely used for the clinical management of acute pain. By combining 2 drugs with different mechanisms of action, such therapy provides additive analgesic effects while reducing the risk for adverse effects. OBJECTIVE: This study compared the efficacy and tolerability of oxycodone 5 mg/ibuprofen 400 mg with those of oxycodone 5 mg/acetaminophen 325 mg, hydrocodone 7.5 mg/acetaminophen 500 mg, and placebo in a dental pain model. METHODS: This was a multicenter, randomized, double-blind, placebo- and active-controlled, parallel-group, single-dose study in patients experiencing moderate to severe pain after surgical removal of > or = 2 ipsilateral impacted third molars. Patients were randomly assigned to receive oxycodone 5 mg/ibuprofen 400 mg, oxycodone 5 mg/acetaminophen 325 mg, hydrocodone 7.5 mg/acetaminophen 500 mg, or placebo. The primary outcome measures were total pain relief through 6 hours after dosing (TOTPAR6), sum of pain intensity differences through 6 hours (SPID6), and adverse events. Secondary efficacy measures included SPID3 and TOTPAR3, peak pain relief, peak pain intensity difference, time to onset of pain relief, time to use of rescue medication, proportion of patients reporting pain half gone, and the patient's global evaluation. RESULTS: Two hundred forty-nine patients (43.5% male; 87.5% white; mean age, 19.1 years; mean body weight, 153.6 pounds) were randomized to treatment as follows: 62 to oxycodone 5 mg/ibuprofen 400 mg, 61 to oxycodone 5 mg/acetaminophen 325 mg, 63 to hydrocodone 7.5 mg/acetaminophen 500 mg, and 63 to placebo. Oxycodone 5 mg/ibuprofen 400 mg provided significantly greater analgesia compared with oxycodone 5 mg/acetaminophen 325 mg, hydrocodone 7.5 mg/acetaminophen 500 mg, and placebo (mean [SD] TOTPAR6, 14.98 [5.37], 9.53 [6.77], 8.36 [6.68], and 5.05 [6.49], respectively; P < 0.001, oxycodone 5 mg/ibuprofen 400 mg vs all other treatments). SPID6 values also differed significantly for oxycodone 5 mg/ibuprofen 400 mg compared with all other treatments (mean: 7.78 [4.11], 3.58 [4.64], 3.32 [4.73], and 0.69 [4.85]; P < 0.001). Oxycodone 5 mg/ibuprofen 400 mg was significantly more effective compared with the other treatments on all secondary end points (P < 0.001, all variables except peak PID vs oxycodone 5 mg/acetaminophen 325 mg [P = 0.006]), with the exception of the time to onset of analgesia. The lowest frequency of nausea and vomiting occurred in the groups that received oxycodone 5 mg/ibuprofen 400 mg (6.5% and 3.2%, respectively) and placebo (3.2% and 1.6%). Rates of nausea and vomiting were significantly lower with oxycodone 5 mg/ibuprofen 400 mg compared with oxycodone 5 mg/acetaminophen 325 mg (P = 0.011 and P = 0.009, respectively) but not with hydrocodone 7.5 mg/acetaminophen 500 mg. CONCLUSIONS: In this study in patients with moderate to severe pain after surgery to remove impacted third molars, oxycodone 5 mg/ibuprofen 400 mg provided significantly better analgesia throughout the 6-hour study compared with the other opioid/nonopioid combinations tested, and was associated with fewer adverse events.

Acetaminophen↗

Staffing model for dental wellness and readiness.

Oral health is an integral part of general health. Previous research has shown that untreated oral conditions can result in increased rates of disease and nonbattle injury for deployed soldiers. The purpose of this study was to develop models for U.S. Army dental wellness and readiness using a multivariate regression analysis approach. Staffing levels and dental wellness and readiness rates were examined for the first three quarters of fiscal year 2002 at 40 Army installations. Full regression model equations were developed for percent dental wellness and readiness using location, time, dental provider types, and basic training installation as predictor variables. Both models were shown to be statistically significant, with wellness R2 = 0.37, F12,107 = 5.18, p < 0.001 and readiness R2 = 0.23, F12,107 = 2.65, p < 0.01. Further tests of specific predictor effects revealed that wellness was significantly associated with the specialties of general dentistry, hygienists, and oral surgery, and that readiness was significantly associated with region and the oral surgery specialty. Results may be useful for the U.S. Army to identify the best practices in an effort to optimize dental wellness and readiness.

Dental Clinics↗

A laboratory technique for teaching root resection.

A simple inexpensive method of making a laboratory model for the teaching of root resection has been presented. The technique of fabrication of the models requires only a rubber dental model mold, extracted or dentiform teeth, laboratory wax, and laboratory stone or plaster. This is one attempt to fulfill the need for developing laboratory exercises for the teaching of the various periodontal procedures.

Apicoectomy↗

Baseline pain and response to analgesic medications in the postsurgery dental pain model.

In designing clinical trials for the treatment of acute pain, enrollment of patients with moderate to severe pain is recommended even when the desired indication is treatment of mild pain. To test this approach, the authors explored the results of two studies that had the same standard placebo-controlled, parallel-group design and that compared the study medication to a single dose of ibuprofen 400 mg. One study had 25 subjects, the other 50 in its ibuprofen arm. Subjects indicating moderate or severe pain (on a scale ranging from 0 = none, 1 = mild, 2 = moderate, 3 = severe) following a surgical extraction of two or more third molars were enrolled. There was a difference between the ibuprofen groups in these two studies in average baseline pain intensity (PI) (2.88 +/- 0.33 vs. 2.26 +/- 0.44). In the higher baseline group, PI decreased faster, achieving lower levels of PI that were maintained for the rest of the study period. The results of pain relief measurements paralleled those of PI. The authors conclude that including patients with a higher degree of baseline pain in the postoperative dental pain model has the potential to increase discrimination of analgesic properties of new drugs.

Adolescent↗

The ICT in situ experimental model in dental research.

The intra-oral cariogenicity test (ICT) in situ experimental model was introduced in 1964 for the study of caries on sample enamel in the human mouth. Slabs of human or bovine enamel are mounted with a Dacron gauze cover in the acrylic flanges of prosthetic appliances. The extent of enamel demineralization or remineralization of lesions is assessed from surface microhardness measurements and microradiography of the enamel sections. The ICT model offers the potential of studying various parameters related to caries. This publication presents a typical ICT study comparing the cariogenicity of 10% sucrose solutions containing 1, 3, 10, and 30 ppm F with that of the control solution, 10% sucrose (without fluoride). The treatments were applied to the ICT as 10-minute extra-oral immersions. The results indicate: (1) a strong effect of F in decreasing demineralization of sound enamel and increasing remineralization of pre-softened enamel in the ICT; (2) pronounced resistance to a subsequent in vitro acid test; (3) pronounced F incorporation into pre-softened enamel; and (4) a characteristic acid-resistant zone, as seen in microradiographs, associated with exposure to F. This in situ model enables one to study experimental caries with repeated testing of enamel that follows the development and/or the regression of subsurface enamel lesions, F incorporation, increased acid resistance, cariogenicity of substrates, and other parameters of caries that can be assessed under standard conditions of tooth substrate and microbial sheltering.

Animals↗

A model of dental public health teaching at the undergraduate level in Peru.

There has been a growing interest among dental educators regarding the opportunities offered by community-based dental education as a means to allow dental students to assume their role as health professionals in the real world. Although several dental schools have integrated community-based education into their curricula, most have not engaged their students in the development of competencies to address dental health needs at the community level. The purpose of this article is to discuss the teaching-learning experiences in dental public health at the undergraduate level in the Faculty of Stomatology at the Universidad Peruana Cayetano Heredia (FS-UPCH) in Lima, Peru. The teaching-learning activities in dental public health at the FS-UPCH consist of two well-defined stages: experiences in low-income urban communities and experiences in low-income rural communities. Both stages have been designed to make it possible for students to acquire competency in addressing oral health needs at the community level as well as to enlarge and deepen their knowledge about the social and health situation in Peru. In community-based dental education, students are not only placed in community settings to treat individual patients, but also challenged to consider dental public health issues, including the administrative aspects of dental services.

Curriculum↗

Rapid prototyping as a tool for diagnosis and treatment planning for maxillary canine impaction.

Treating an impacted maxillary canine requires identifying its exact position; this can pose a challenge to both orthodontists and oral surgeons. The purpose of this article is to present a new method for diagnosis and treatment planning of maxillary canine impaction by using computed tomography combined with rapid prototyping. Computed tomography image files of a patient with tooth 13 impaction were edited to produce, by means of rapid prototyping, an anatomic model of the maxillary teeth and a single attachment model that was later used to fabricate a metal attachment to be bonded to the impacted tooth. The dental model was used in the diagnosis and orthodontic treatment planning, and to communicate with the patient and his parents. The model showed the exact anatomical relationship between the impacted tooth and the other teeth; it was the main aid in intraoperative navigation during surgery to expose the tooth. The metal attachment built from the prototype was bonded to tooth 13 during surgery. Prototyping could become a new tool for fabricating brackets and other precision accessories for specific needs. Dental models made with rapid prototyping could become the diagnostic procedure of choice for evaluating impacted maxillary canines.

Adolescent↗

Response to the dental scientist model.

In general, considerable strength and much realism exist in the model as presented by Dr. McHugh. Progress in biological science is central to any scheme anticipating change in medicine, including dental and oral medicine. In my view, there are two weaknesses in his presentation: 1) a perhaps semantic difference with me over whether dentists should be trained as scientists or as individuals who can use science (fact and process); and 2) a substantive difference as to how to reinforce didactic, basic biomedical science in clinical training.

Biological Science Disciplines↗

Accuracy of a system for creating 3D computer models of dental arches.

Three-dimensional imaging of dental tissues will have a major impact in dentistry if the images are accurate. The purpose of this study was to measure the accuracy and precision of a system for creating three-dimensional images of dental arches. Using vinyl polysiloxane impression materials and improved dental stone, we made 10 stone casts of a "dental" standard with known dimensions. The impressions and casts were scanned by means of a Comet 100 optical scanner. Custom software created three-dimensional images (computer models) from the scanned data. Accuracy was defined as the average of the absolute differences between the computer models and the standard. Precision was the standard deviation of accuracy over 10 repeated measures. Software processing improved the accuracy of the scanner data. Accuracy +/- precision for the casts and impressions was 0.024 +/- 0.002 mm and 0.013 +/- 0.003 mm, respectively. The system produced computer models with sufficient accuracy for clinical application.

Algorithms↗

The effect of fixture neck design in a realistic model of dental implant: a finite element approach.

The aim of this work is to develop an accurate finite element model able to reproduce a standard experimental set-up for the evaluation of mechanical failure of a dental implant system. The considered system is composed of a fixture, an abutment and a connecting screw. We analysed the behaviour of the implant system considering three different designs of the fixture, in order to establish which one provides the better mechanical behaviour. After the definition of the numerical models, loading conditions were selected in order to reproduce the same stress state found in previous mechanical failure tests. Preloading and functional loading conditions were simulated. The analysis of the numerical results shows that the structure yielding is due to the fixture neck plastic deformation, that increases the load eccentricity and then the bending stress on the connecting screw. Only slight differences were found between the three implant systems in the amount and distribution of stress. The model reproduces properly the implant systems and the experimental set-up. The goodness of the model can be summarised as: realistic geometrical structure, elastoplastic model for the material description, correct definition of the contacts and the existing tolerance among the different system components, reproduction of the preloading stress condition. The present study permitted to define a valid procedure for the realization of numerical models of implant systems.

Computer Simulation↗

Laboratory comparison of a titanium trauma splint with three conventional ones for the treatment of dental trauma.

AIM: This was to evaluate the efficacy of a Titanium Trauma Splint (TTS) by comparing it with three other devices commonly used in the care of dental trauma, a Resin Splint (RS), Button-Bracket Splint (BS) and a Wire- Composite Splint (WCS). METHODS: The four types of splints were applied on experimental dental models, including in the splints the teeth from canine to canine of each maxilla. Two load-tests for each device were applied with the dental model inclined to 45 degrees or less, and increasing forces were applied to the incisal edges from 0N to 50N, in the first test, and from 0N to 100N in the second. At the same time the displacement involved of the splinted teeth was assessed and then the ratio between the two measured sizes was graphically represented. RESULTS: In the level tests the displacements of the splinted teeth caused by the force of 80N were: 0.39 mm for the BS, 0.37 mm for the TTS, 0.35 mm for the WCS and 0.30 mm for the RS. In the inclined tests, the splints under the effect of 40N, showed displacements as: 1.65 mm RS, 1.83 mm BS, 1.89 mm TTS and 2.16 mm WCS. CONCLUSION: With the exception of RS as to rigidity, the other three splints were practically the same in response. Considering other characteristics, the TTS proved to be a promising device for the treatment of dental traumas.

Composite Resins↗