fracture pattern of maxillary incisors in children and adolescence: a new morphological classification

Traumatic dental injuries are frequent in the maxillary anterior teeth for variety of reasons like falling down in street or school, collision and sports. Many local occlusal factors such as increased overjet and general factors such as increased activity may predispose and modify these traumatic injuries. Many studies have attempted to classify the types of traumatic dental injuries based on the extent of the tooth structure involvement and the severity of the trauma. Central incisors act as one unified segment during traumatic injuries and do fracture always in certain repeated morphological patterns every time they are subjected to impact trauma. One hundred and forty [140] children were examined at their first presentation in the restorative-pe-diatric dentistry department and data was collected from new dental traumatic injuries in order to classify these morphological patterns of trauma and see which of them are happening more than others and their relationship with overjet. Data revealed that there were repeated fracture patterns which can be divided into seven morphological categories and increased overjet was more predisposeing factor

reversible diagnostic method for occlusal, esthetic and functional evaluation of full arch re-construction: a novel approach using thermoplastic retainers

Patients presented for extensive tooth wear frequently need elaborated case study and analysis for all occlusal, muscular and TMJ factors before final and definitive treatment is commenced. This includes thorough and comprehensive assessment of the occlusal scheme. A preoperative visualization of the final esthetic results in vivo is essential before deciding to go for a particular treatment option, especially when tooth preparation is part of the treatment plan. The two major factors that concern patients with extensive tooth surface loss are increasing occlusal vertical dimension and esthetic modification to the present situation, where some patients cannot visualize the new situation even when seen on animated software or modified photographs for illustrated purposes In this paper the authors have discussed a reversible and versatile method for esthetic and occlusal assessment for cases of sever tooth wear, which would allow patients to "practice" their new treatment in reality, and allow them to evaluate its functional and esthetic merits before deciding to choose that particular treatment option. In this diagnostic method, the masticatory system is allowed to adapt to the new treatment approach easily with the option of modifications at all levels or even cancelling the whole treatment without any adverse effect on the teeth or the masticatory apparatus

tensile peel strength of cantilever Ni/Cr resin bonded bridegs

To measure the tensile peel strength of Ni/Cr cantilever resin-bonded bridges. Ten extracted upper sound human premolars were prepared with the wrap around preparation with occlusal rest for construction of Ni/Cr resin-bonded bridges. The metal retainers were then sandblasted with 50 micro m Aluminium oxide grit, cleaned in an ultrasonic bath for three minutes and bonded to the extracted teeth using Panavia 21 resin according to the manufacturer instructions and tested on an Instron universal testing machine for tensile peeling bond strength. The results of this study showed that the range of tensile peel strength was ranged between 15.3-31.9 Newton [mean 22.5 N], which is virtually much less than the published tensile bond strength values, yet resin-bonded bridges do fail at these loads. This study provided quantitative values of the tensile peeling strength by which resin-bonded bridges thought to be failing intraorally. These values showed to be well below the tensile bond strength or shear bond strength, yet it was enough to break the resin cement and to debond the resin-bonded bridges. The suggested mechanism is that the metal framework will be deformed during function, causing stress concentration in the resin layer followed by initiation of a crack, which will propagate through the bonded surface-causing breakdown by cohesive failure. This study supports the hypothesis that resin-bonded bridges do peel out of the abutment as the likely cause of failure at normal functional masticatory loads

Involvement of renin-angiotensin system in hypertensive effect of cadmium in rats.

Role of renin-angiotensin system in hypertension induced by cadmium chloride (CdCl2) in rats has been investigated. Intravenous administration of CdCl (1 mg/kg) produced a biphasic response i.e. a transient fall followed by a marked and consistent rise in blood pressure. The peak hypertensive effect was accompanied by raised PRA levels. Pretreatment with captopril (1 mg/kg, i.v.) losartan (1 mg/kg, i.v.) or captopril + losartan attenuated the pressor response to Cd by 62%, 42% and 100% respectively in separate groups. Central administration of Cd (10 micrograms/rat, i.c.v.) showed a biphasic response similar to that observed after i.v. route. However, it was not accompanied by raised PRA levels. Prior treatment with losartan (10 micrograms/rat, i.c.v.) completely abolished the pressor response to Cd (i.c.v.) whereas it was not affected significantly by captopril (10 micrograms/rat, i.c.v.). On the other hand, centrally administered losartan only partially reduced the pressor response to i.v. Cd. The results are discussed in light of a differential involvement of central vs peripheral renin-angiotensin system in the hypertensive effect of Cd.

Cadmium induced nephrotoxicity in rats.

Onset of hypertension and nephropathy after 1,2, and 4 weeks of exposure to cadmium chloride (1 mg/kg, ip) was studied in rats by measuring changes in blood pressure and renal function (urinary output, electrolytes, serum creatinine, inulin clearance and Na+K+ ATPase). Significant decrease in body weight and rise in blood pressure were observed as early as one week of exposure while microalbuminuria was detected in 50% of the animals after 2 weeks. Na+K+ ATPase, a renal tubular enzyme, was depressed after 1 week with maximum lowering occurring after 4 weeks. There were no detectable changes in fluid intake, urine output, electrolytes, inulin clearance and serum creatinine even after 4 weeks. It is concluded that hypertension and tubular lesion set in earlier than glomerulopathy as indicated by microalbuminuria and the latter could be the consequence of rise in blood pressure.