Assessing bone's adaptive capacity around dental implants: A literature review

BackgroundIncreased stress (force) on prostheses induces strain (deformation) in the peri-implant bone. Elevated stress and strain could result in the failure of implants that support prostheses. However, the survival rate of implants supporting prostheses under increased stress is high. Either the bone is stronger than expected or it adapts to increased stress. Concepts regarding bone’s adaptive capacity continue to evolve and are the focus of this literature review.Types of Studies ReviewedThe authors searched the literature to find studies that addressed the bone’s capacity to adjust to increased stress and strain. They assessed experimental and clinical trials in which investigators monitored healing after placement of dental implants.ResultsThe data indicate that forces greater than the bone’s adaptive ability can induce loss of osseointegration, as well as osseous resorption. In contrast, it is possible that increased stress on prostheses initiates a reparative process, thereby facilitating retention of implants experiencing increased stress. Numerous lines of evidence support the concept that bone can modify itself to withstand increased mechanical forces.Practical ImplicationsThe authors provide an explanation for the high success rate of prostheses and implants in bone that are exposed to increased stress and strain.     

Acute complications after laparoscopic bariatric procedures: update for the general surgeon

Background

Development and widespread use of laparoscopic bariatric surgery exposes emergency room physicians and general surgeons to face acute or chronic surgical complications of bariatric surgery.

Methods

The most common surgical emergencies after bariatric surgery are examined based on an extensive review of bariatric surgery literature and on the personal experience of the authors' practice in four high-volume bariatric surgery centers.

Results

An orderly stepwise approach to the bariatric patient with an emergency condition is advisable. Resuscitation should follow the same protocol adopted for the non-bariatric patients. Consultation with the bariatric surgeon should be obtained early, and referral to the bariatric center should be considered whenever possible. The identification of the surgical procedure to which the patient was submitted will orient in the diagnosis of the acute condition. Procedure-specific complication should always be taken into consideration in the differential diagnosis. Acute slippage is the most frequent complication that needs emergency treatment in a laparoscopic gastric banding. Sleeve gastrectomy and gastric bypasses may present with life-threatening suture leaks or suture line bleeding. Gastric greater curvature plication (investigational restrictive procedure) can present early complications related to prolonged postoperative vomiting. Both gastric bypass and bilio-pancreatic diversion may cause anastomotic marginal ulcer, bleeding, or rarely perforation and severe stenosis, while small bowel obstruction due to internal hernia represents a surgical emergency, also caused by trocar site hernia, intussusceptions, adhesions, strictures, kinking, or blood clots. Rapid weight loss after bariatric surgery can cause cholecystitis or choledocholithiasis, which are difficult to treat after bypass procedures.

Conclusions

The general surgeon should be informed about modern bariatric procedures, their potential acute complications, and emergency management.     

Imagery of different sensory modalities: hypnotizability and body sway

Postural control in subjects with high (Highs) and low (Lows) susceptibility to hypnosis is differentially affected by changes in visual and neck tactile/proprioceptive input. The aim of the present experiment was to investigate whether imagery of the visual and tactile sensory modalities also induces different modulation of postural control in Highs and Lows. Fourteen Highs and 16 Lows were included in the study; they were recorded while standing upright with eyes closed during visual and tactile imagery tasks and during mental computation. Their posture and movement were recorded with an Elite System and their experience was assessed after each task in a structured interview. Visual imagery was judged “easier” than tactile imagery by Lows, while Highs performed both tasks easily and judged the tactile imagery less effortful and more vivid than Lows. No difference was observed for the mental computation. The Highs’ body sway was not affected by the cognitive tasks, while Lows showed a task-related modulation of body sway. The results are in line with the hypothesis of lower vulnerability of Highs to the effects of tasks interfering with postural control and of different sensory-motor integration in Highs and Lows.     

The relationship between biologic concepts and fabrication of surgical guides for dental implant placement

This article reviews guidelines for construction of surgical guides to direct dental implant placement. Biologic principles are discussed with regard to the mesiodistal, buccolingual, and apicocoronal insertion of implants. The application of these data to develop surgical guides is discussed. Also, with respect to specific prosthetic reconstructions, a variety of guides are described that can be fabricated for partially and fully edentulous arches.     

Diastolic paradoxic jet flow in patients with hypertrophic cardiomyopathy: report of two patients with different morphologic aspects

BACKGROUND: In non-Asiatic population, apical hypertrophic cardiomyopathy represents 1% to 2% of hypertrophic cardiomyopathies. The presence of an apical ventricular aneurysm occurs in 1% of patients with the apical variant of hypertrophic cardiomyopathy. METHODS AND RESULTS: We present two patients with hypertrophic cardiomyopathy, both illustrating an early diastolic paradoxic jet flow between the apex and the middle area of ventricle. Such paradoxic flow is possibly due to the coexistence of mid-chamber obliteration and segmental wall motion abnormalities at the apex. The incidence and clinical significance of this flow pattern is still to be clarified.     

Electrophysiological effects and clinical efficacy of propafenone in children with recurrent paroxysmal supraventricular tachycardia

Twenty-four patients aged 10.1 +/- 4.5 (mean +/- SD) years with recurrent paroxysmal supraventricular tachycardia underwent an electrophysiological study. Eleven patients had an overt and seven had a concealed accessory connection; six patients had no accessory connection. An orthodromic reciprocating tachycardia was inducible in 17 of 18 patients with an accessory connection, and an atrioventricular nodal reentrant tachycardia was inducible in four of six patients without accessory connection. After administration of propafenone, the sinus cycle length decreased. Intra-arterial, intranodal, and His-ventricle intervals and QRS duration increased. The atrial and ventricular effective refractory periods and anterograde and retrograde effective refractory periods of the atrioventricular node increased. The cycle length at which nodal second-degree block occurred increased. Of 18 patients with accessory connection, propafenone prolonged retrograde conduction in all, blocked anterograde conduction in five, and prolonged it in six. The drug terminated the orthodromic reciprocating tachycardia in all 17 patients and the atrioventricular nodal reentrant tachycardia in three of four patients. In three of four patients with atrioventricular nodal reentrant tachycardia and in 15 of 17 patients with orthodromic reciprocating tachycardia, the tachycardia was no longer inducible or nonsustained after propafenone. A follow-up of 26 +/- 10 months revealed that the drug when orally administered to all patients prevented recurrences of tachycardia in 15 of 18 patients with and in four of six patients without accessory connection. The results of short-term drug testing with propafenone predict the response to long-term oral therapy with this drug.     

Nonreceptor tyrosine protein kinase pp60c-src in spatial learning: synapse-specific changes in its gene expression, tyrosine phosphorylation, and protein-protein interactions

c-src is a nonreceptor tyrosine protein kinase that is highly concentrated in synaptic regions, including synaptic vesicles and growth cones. Here, we report that the mRNA signal of pp60c-src is widely distributed in the rat brain with particularly high concentrations in the hippocampus. After spatial maze learning, up-regulation of c-src mRNA was observed in the CA3 region of the hippocampus, which was accompanied by increases in pp60c-src protein in hippocampal synaptosomal preparations. Training also triggered an increase in c-src protein tyrosine kinase activity that was correlated with its tyrosine dephosphorylation in the synaptic membrane fraction. After training, pp60c-src from hippocampus showed enhanced interactions with synaptic proteins such as synapsin I, synaptophysin, and the type 2 N-methyl-d-aspartate receptor, as well as the cytoskeletal protein actin. The association of pp60c-src with insulin receptor in the synaptic membrane fraction, however, was temporally decreased after training. Furthermore, in vitro results showed that Ca(2+) and protein kinase C might be involved in the regulation of protein-protein interactions of pp60c-src. These results suggest, therefore, that pp60c-src participates in the regulation of hippocampal synaptic activity during learning and memory.