Proximal contact tightness between direct-composite additions in the posterior dentition: an in vitro investigation.

PURPOSE: The aim of the study was to test whether a novel three-step matrix technique for posterior direct-composite additions creates sufficiently strong proximal contacts. MATERIALS AND METHODS: Contact tightness was measured between direct-composite additions and between original teeth on a model. Therefore, the frictional forces required to remove a straight, 0.05-mm-thick, metal matrix band inserted between adjacent teeth and held by a universal testing machine (Zwicki, Zwick GmbH, Ulm, Germany) were recorded. Measurements were taken at three time points to carry out reference analysis: at baseline, after removal of the maxillary right second premolar (tooth #15) to simulate a diastema, and after closure of the diastema by inserting two direct-composite additions with the three-step matrix technique on the maxillary right first premolar (tooth #14) and first molar (tooth #16). Measurements were performed in the maxillary right (first) and left (second) quadrants to document sagittal displacement. RESULTS: The original contact tightness values were between 1.65 ± 0.88 N and 3.05 ± 0.60 N in the first quadrant and between 1.23 ± 0.51 N and 2.18 ± 0.43 N in the second quadrant. After removal of tooth 15, values decreased significantly in the first quadrant and insignificantly in the second. After reconstruction, the contact tightness between teeth 14 and 16 was significantly stronger (tighter) (3.20 ± 0.80 N) than the originally measured contact tightness between teeth 14 and 15 (2.86 ± 0.64 N) and teeth 15 and 16 (1.65 ± 0.88 N) (p=0.006 and 0.001, respectively). CONCLUSIONS: Within the limitations of an in vitro investigation, this study has shown that by using a novel, three-step matrix technique, direct posterior composite additions can form sufficiently tight proximal contacts.

Louis H. Bauer and the origins of civil aviation medicine.

With the passage of the Air Commerce Act in May 1926, civil aviation safety became a federal responsibility under the Department of Commerce (DoC). In November of that year, Louis Hopewell Bauer (1888-1964) became the DoC's first Aviation Medical Director. After earning his medical degree at the Harvard School of Medicine in 1912, Bauer joined the U.S. Army Medical Corps, where he helped develop the role of the military flight surgeon and then served as director of the Army's School of Aviation Medicine. Upon taking the federal position, he undertook to define medical standards and examination frequencies for civilian pilots and identifiy disqualifying conditions that could compromise a pilot's ability to operate an aircraft safely. Bauer also personally selected 57 private physicians (soon to be known as Aviation Medical Examiners) distributed across the country to give medical examinations for pilot licenses. Bauer subsequently played a leading role in organizing the Aviation Medical Association in 1929.

Fiber-reinforced composite fixed dental prostheses: a retrospective clinical examination.

PURPOSE: To obtain survival data on 32 fiber-reinforced fixed dental prostheses which were inserted in our department and to rate the quality of these restorations on the basis of esthetic, biological, and functional parameters. MATERIALS AND METHODS: Thirty-two patients with fiber-reinforced fixed dental prostheses were included in the study. The fiber frameworks were made of a polymer-monomer-preimpregnated continuous unidirectional glass fiber material. The survival times, failure events, and clinical parameters were recorded. Restorations in function without previous failure were classified as "Overall Survival". The classification "Functional Survival" was assigned in the event of minor failure and subsequent repair. Loss of the restoration was regarded as "Failure". The quality rating was performed using modified USHPS/Ryge criteria. RESULTS: The follow-up interval ranged from 2 to 64 months with a median follow-up time of 18.2 months. Twenty-four restorations were classified as "Overall Survival", seven were classified as "Functional Survival", and one was classified as "Failure". The overall survival at the median follow-up time was 74.4%. For the majority, the quality rating (USHPS/Ryge criteria) yielded clinically excellent results in all categories. No restoration was rated as insufficient or poor. CONCLUSION: Fiber-reinforced composite fixed dental prostheses provide sufficient stability and very good esthetic, biological, and functional performance in the case of specific clinical indications.

Recontouring teeth and closing diastemas with direct composite buildups: a clinical evaluation of survival and quality parameters.

OBJECTIVES: Irregular tooth shape and position in the anterior maxilla and mandible are major aesthetic problems for patients. In recent years such conditions have increasingly been treated minimally or even non-invasively by recontouring teeth with direct composite resin buildups. Although clinical experience with this treatment option is promising, evidence-based data about longevity are limited. METHODS: The authors evaluated survival and quality of 327 composite buildups that were placed in 101 patients in the Department of Conservative Dentistry, University of Heidelberg, between 2002 and 2008. Follow-up intervals and failures were recorded. Quality was assessed by grading restorations (modified USPHS/Ryge critera) still in situ without adverse event during the follow-up period. RESULTS: After a mean follow-up interval of 27.8 months, 284 restorations were in situ and had no event. Forty-two restorations were in situ but had events that were mostly minor fractures of the composite resin. One restoration had been lost. Analysis of the time from insertion to any event or end of follow-up yielded an estimated 5-year survival rate of 79.2% (95% CI, 70.5-87.9). Quality was assessed by grading in situ restorations without event. More than 90% of graded restorations were categorized as "clinically excellent" (1) or "clinically good" (2). A correlation between those rated "clinically sufficient" or worse (≥3) and the follow-up period was observed. CONCLUSIONS: Direct composite buildups are aesthetic, functional, and biologically sound treatment options for recontouring teeth and closing diastemas with clinically promising survival rates. Therefore, tooth shape correction can be recommended in cases in which minimally invasive or non-invasive procedures on healthy teeth are indicated.