The Conometric Concept: Definitive Rehabilitation of a Single Posterior Implant Using a Friction Retention Abutment. A 1-year Follow-up Report

PURPOSE

To provide a 1-year assessment of friction-retention abutments (Acuris, Dentsply Sirona) used to retain a single lithium disilicate (LS2) monolithic restoration.

MATERIALS AND METHODS

A total of 522 implants were placed to treat single-tooth premolar and molar edentulous sites in the mandible or maxilla. Three types of implants were used. The tested abutments were connected 3 months after implant placement. A single pressed LS2 monolithic restoration was cemented to a dedicated titanium cap and engaged to the abutment without the use of screws or cement. Any complications affecting the restoration or the opposing dentition, soft tissue dimensional changes, the distance between the implant platform and the bone peak, and pocket probing depths were recorded at the time of restoration placement (T0), after 6 months of function (T1), and after 1 year of function (T2). Esthetic, functional, and biologic parameters were recorded at T0 and T2.

RESULTS

A total of 507 patients (284 women and 223 men) received a restoration (T0), and 504 of them reached the T2 1-year follow-up. One restoration fractured after 10 months in function. No statistically significant difference was assessed in the soft tissue measurements or in the measurements of the distance between the supporting implant platform and the bone peak. None of the restorations detached during the observation period.

CONCLUSION

The friction retention abutment is a viable option to retain an implant-supported monolithic LS2 glass-ceramic restoration in cases of premolar or molar single-tooth edentulism.

Fixed Partial Restorations Made of a New Zirconia-Reinforced Lithium Silicate Material: A 2-Year Short-Term Report

PURPOSE

To evaluate the 2-year performance of definitive implant- or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate placed to restore premolars and molars in clinical cases of partial edentulism.

MATERIALS AND METHODS

All patients received a three-unit fixed restoration made of monolithic, hot-pressed, zirconia-reinforced lithium silicate glass-ceramic. The restoration was cemented to two natural teeth or attached to two 3.5- or 4.5-mm-diameter square threaded, grit-blasted, acid-etched integrated implants with a Morse taper connection. Peri-implant pocket depth and bone and soft tissue remodeling were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the World Dental Federation study design were assessed yearly until the final follow-up appointment. At the time of placement of the definitive restorations and at the 2-year follow-up visit, the opposing dentitions were identified by type of restoration and supporting structures.

RESULTS

A total of 100 patients were consecutively enrolled in the period between June 2016 and July 2017, and 50 patients each received an implant-supported restoration (Group A) or a tooth-supported restoration (Group B). One (2%) of the 50 implant-supported prostheses fractured after 21 months of function. None of the other prostheses failed or became loose or detached. No significant differences involving probing levels or bone and soft tissue remodeling were found between the follow-up times. No cases of inflammation or infection of the mucosal cuff around the neck of the implants were recorded. The most common issue occurred immediately after placement of the prosthesis, when 3 patients (6%) from Group A and 4 patients (8%) from Group B asked for a modification of tooth shade.

CONCLUSION

Implant-supported or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate can be used to successfully restore cases of posterior partial edentulism. The 2-year results of this report will be studied more in depth in ongoing long-term research.

The Conometric Concept: A 5-Year Follow-up of Fixed Partial Monolithic Zirconia Restorations Supported by Cone-in-Cone Abutments

The use of the cone-in-cone connection to support definitive restorations was previously evaluated in cases involving full-acrylic resin or hybrid acrylic-resin composite prostheses. The aim of this study was to evaluate the performance of definitive fixed partial prostheses made with monolithic zirconia and supported by cone-in-cone abutments and integrated implants. Implants were placed into healed sites and fresh extraction sockets. The prostheses were placed in the posterior regions of partially edentulous patients after healing periods of 3 months. A total of 76 patients received fixed monolithic zirconia restorations splinted with cone-in-cone connections to two implants that were followed up yearly for 5 years. At each follow-up visit, peri-implant bone levels and pocket depths were recorded. Esthetic, functional, and biologic United States Public Health Services parameters modified by the World Dental Federation study design were assessed at the last follow-up appointments. The opposing dentition was categorized by type of restoration and supporting structure at the time of placement of the definitive zirconia partial restoration and at the 5-year follow-up. The treatment achieved an 88.2% success rate and a 97.4% survival rate at the 5-year follow-up. None of the prostheses became loose or detached. One fixed prosthesis (0.76%) fractured 41 months after placement. No significant difference involving peri-implant bone and probing levels between the experimental times was found. The results of this research indicated that abutment-prosthesis cone-in-cone connections were successful within the 5-year study period.

The Conometric Concept: A Two-Year Follow-Up of Fixed Partial CEREC Restorations Supported By Cone-In-Cone Abutments

PURPOSE

To evaluate the performance of definitive, implant-supported, lithium disilicate fixed dental prostheses (LS₂ FDPs) manufactured with a computer-assisted design/computer-assisted manufacturing (CAD/CAM) system. All patients received two-unit restorations placed in posterior regions, supported by osseointegrated implants with cone-in-cone connection abutments.

MATERIALS AND METHODS

Two implants (Ankylos) were placed into healed sites or fresh extraction sockets in the maxillary/mandibular posterior regions of partially edentulous patients. Definitive digital impressions were made 3 months after surgery. Twenty-four patients received fixed  monolithic LS₂ restorations manufactured with the CEREC system. All restorations were connected to the implants using cone-in-cone connection abutments. Peri-implant pocket depths were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed yearly until the last follow-up appointment. The opposing dentitions were identified by type of restoration and supporting structures at the time of placement of the definitive restorations and at the 2-year follow-up visits.

RESULTS

One patient (4.16%) moved to an unknown location during the study. A total of 23 FDPs (95.8%) supported by 46 implants reached the 2-year follow-up. None of the prostheses failed, or became loose or detached. No significant difference involving probing levels between the experimental times were found.

CONCLUSIONS

The results of this research indicated that the abutment-prostheses connection using a cone-in-cone approach was successful within the 2-year period of this study. None of the studied monolithic LS₂ glass-ceramic prostheses milled using the CEREC CAD/CAM system fractured or became detached.

Retention Strength of Conical Welding Caps for Fixed Implant-Supported Prostheses

PURPOSE

This study evaluated the retention strength of welding caps for Ankylos standard abutments using a pull-out test.

MATERIALS AND METHODS

Each sample consisted of an implant abutment and its welding cap. The tests were performed with a Zwick Roell testing machine with a 1-kN load cell.

RESULTS

The retention strength of the welding caps increased with higher abutment diameters and higher head heights and was comparable or superior to the values reported in the literature for the temporary cements used in implant dentistry.

CONCLUSION

Welding caps provide a reliable connection between an abutment and a fixed prosthesis without the use of cement.

The Conometric Concept: Coupling Connection for Immediately Loaded Titanium-Reinforced Provisional Fixed Partial Dentures-A Case Series

The aim of this prospective study was to demonstrate the feasibility of the conic coupling connection as a novel approach for the retention of immediately loaded, titanium-reinforced, temporary fixed partial restorations. The patients received a fixed, immediate partial restoration, attached using the conic coupling connection to two implants placed in a fresh extraction socket. Changes in marginal peri-implant bone level or probing depth measurements, biologic or technical complications, and any other adverse event were recorded at yearly follow-ups up to 3 years after implantation. A total of 78 implants placed in 39 patients reached the 3-year follow-up. A trend of bone overgrowth over the implant platform (mean: 0.2 mm) and a complete fill of the vertical gap between the implant platform level and the first point of contact of the bone with the implant surface was seen after the 6-month follow-up. No disconnection of any prosthesis was noted during 3 years of full occlusal function. The results of this study suggest that titanium-reinforced, temporary partial restorations with conic coupling retention supported by immediate implants provide a successful, cost-effective treatment modality.

Fatigue limits of titanium-bar joints made with the laser and the electric resistance welding techniques: microstructural characterization and hardness properties

Fatigue behavior of the titanium bars is of utmost importance for the safe and reliable operation of dental implants and prosthetic constructions based on these implants. To date, however, only few data are available on the fatigue strength of dental prostheses made with electric resistance welding and laser welding techniques. This in-vitro study highlighted that although the joints made with the laser welding approach are credited of a superior tensile strength, joints made with electric resistance welding exhibited double the minimum fatigue strength with respect to the joints made with laser welding (120 vs 60 N).

The Conometric Concept: Definitive Fixed Lithium Disilicate Restorations Supported by Conical Abutments

PURPOSE

The use of the conical coupling connection to support definitive restorations was evaluated in cases involving full acrylic resin or hybrid acrylic resin-composite prostheses. The aim of this study was to evaluate the performance of definitive fixed partial prostheses made with lithium disilicate and supported by coupling connection abutments and healed implants.

MATERIALS AND METHODS

The prostheses were placed in the posterior regions of partially edentulous patients; 65 patients received fixed lithium disilicate restorations splinted with conical coupling connections to two implants. Implants were placed into healed sites and fresh extraction sockets. The prostheses were placed after healing periods of 3 months: restorations were followed yearly for 3 years. At each follow-up visit, peri-implant bone levels and pocket depths were recorded. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed at the last follow-up appointments.

RESULTS

Two prostheses (3.07%) fractured: one was related to framework design error; one was caused by a car accident. Three patients reported small chips: these restorations were immediately polished. No significant difference involving peri-implant bone and probing levels between the experimental times were found. None of the prostheses became loose.

CONCLUSIONS

The results of this research indicated that abutment-prostheses coupling connections were successful within the timeframe of this study.

Microstructural characterization and hardness properties of electric resistance welding titanium joints for dental applications

The electric resistance welding procedure is used to join a titanium bar with specific implant abutments in order to produce a framework directly in the oral cavity of the patient. This investigation studied the effects of the welding process on microstructure and hardness properties of commercially pure (CP2 and CP4) Ti components. Different welding powers and cooling procedures were applied to bars and abutments, normally used to produce the framework, in order to simulate the clinical intraoral welding procedure. The analyses highlighted that the joining process did not induce appreciable changes in the geometry of the abutments. However, because of unavoidable microstructural modifications in the welded zones, the hardness decreased to values lower than those of the unwelded CP2 and CP4 Ti grades, irrespective of the welding environments and parameters.

Immediate rehabilitation of the edentulous mandible using Ankylos SynCone telescopic copings and intraoral welding: a pilot study

The aim of this prospective study was to assess the suitability of immediate rehabilitation of the edentulous mandible using SynCone copings and the intraoral welding technique. Patients with an edentulous mandible were fitted with a removable restoration supported by an intraorally welded titanium bar. Copings were connected to their respective SynCone 5-degree abutments and then welded to a titanium bar using an intraoral welding unit. This framework was used to support the definitive restoration, which was delivered on the day of implant placement. Restoration success and survival, implant success, and biologic or technical complications were assessed immediately after surgery and at 6 and 12 months. Twenty-two patients were consecutively treated with 88 immediately loaded implants. No acrylic resin fractures or radiographically detectable alterations of the welded frameworks were present in the 22 restorations delivered. One implant (1.1%) failed 1 month after surgery; all remaining implants (98.9%) were clinically stable at the 12-month follow-up. Within its limitations, this pilot study demonstrated that it is possible to successfully rehabilitate the edentulous mandible on the day of surgery with a definitive restoration supported by an intraorally welded titanium framework and SynCone 5-degree abutments.

Immediate loading of zygomatic implants using the intraoral welding technique: a 12-month case series

The aim of this prospective study was to evaluate the concept of intraoral welding as a suitable technique for fabricating a fixed restoration for the edentulous maxilla the day of surgery using standard and zygomatic implants. Ten consecutive patients (four men, six women; mean age, 62.3 ± 11.6 years) were involved in this study, each of whom had an edentulous atrophic maxilla and received two standard and two zygomatic implants. All implants were loaded immediately with a fixed prosthesis supported by an intraorally welded titanium framework. Definitive abutments were connected to the implants, and a titanium bar was welded to them using an intraoral welding unit. This framework was used to support the definitive prosthesis, which was fitted the day of implant placement. Patients were checked for swelling, pain, and framework stability at 1, 3, 6, and 12 months. A total of 20 immediately loaded standard and 20 zygomatic implants were used. The cases included in this study achieved a 100% prosthetic success rate at the 12-month follow-up. No fracture or radiographically detectable alteration of the welded frameworks was noticed. It is possible to successfully rehabilitate the edentulous atrophic maxilla with a permanently fixed prosthesis supported by an intraorally welded titanium framework attached to standard and zygomatic implants the day of surgery.

10-year follow-up of immediately loaded implants with TiUnite porous anodized surface

BACKGROUND

The immediate loading of implants with a porous anodized surface is a well-described technique. Few data are however available on the long-term outcomes.

PURPOSE

The aim of this prospective study was to assess the 10-year performance of TiUnite implants supporting fixed prostheses placed with an immediate loading approach in both postextractive and healed sites.

MATERIALS AND METHODS

All patients received a fixed provisional restoration supported by immediately loaded parallel design, self-tapping implants with a porous anodized TiUnite surface, and an external-hexagonal connection. Both healed and postextractive cases were included. Success and survival rate for restorations and implants, changes in marginal peri-implant bone level, probing depth measurements, biological or technical complications, and any other adverse event were recorded at yearly follow-up up to 10 years after surgery.

RESULTS

A total of 210 implants fulfilled the inclusion criteria and were consecutively placed in 59 patients. Forty-seven (22.38%) implants were lost because of the recalled patient refused to attend the planned 10-year follow-up. Five over 210 (2.38%) implants were lost. At the final follow-up, the accumulated mean marginal bone loss and probing depth were, respectively, 1.93 mm (SD 0.40) and 2.54 mm (SD 0.44) for the implants placed in healed sites (n = 84); 1.98 mm (SD 0.37) and 2.63 mm (SD 0.39) for the implants placed in postextractive sites (n = 74). The restorations examined achieved a cumulative 65.26% success rate and 97.96% survival rate. The implants placed in healed and postextractive sites, respectively, achieved a 98.05% and a 96.52% cumulative survival rate.

CONCLUSIONS

Positive results in terms of bone maintenance in the long-term perspective are to be expected using immediately loaded implants with a TiUnite porous anodized surface in both postextractive and healed sites when adequate levels of oral hygiene are kept.

Immediate loading of the edentulous maxilla with a definitive restoration supported by an intraorally welded titanium bar and tilted implants

PURPOSE

The aim of this prospective study was to evaluate the concept of intraoral welding as a suitable technique for the fabrication of a restoration for the edentulous atrophic maxilla on the day of placement of axial and tilted implants.

MATERIALS AND METHODS

Thirty patients received three axial and four tilted implants in the edentulous maxilla. Immediately after implant placement, definitive abutments were connected to the implants and then a titanium bar was welded to them using an intraoral welding unit. This framework was used as a support for the definitive restoration, which was attached on the day of implant placement. Mean marginal bone loss and radiographically detectable alteration of the welded framework were assessed using periapical radiographs immediately after surgery and at 6, 12, 24, and 36 months after placement.

RESULTS

Sixteen men and 14 women with an average age of 58.1 years (SD 13.6) were consecutively treated with 210 immediately loaded implants. No fractures or radiographically detectable alterations of the welded frameworks were evident. A 100% prosthetic success rate was seen at 36 months. Three (1.4%) implants had serious biologic complications, resulting in success rates of 97.8% for axial implants and 99.2% for tilted implants. The accumulated mean marginal bone loss was 0.92 mm (SD 0.75; n = 90) for axial implants and 1.03 mm (SD 0.69; n = 120) for tilted implants. The average pocket probing depths were 1.87 mm (SD 0.98; n = 90) for the axial implants and 1.95 mm (SD 0.81; n = 120) for the tilted implants.

CONCLUSIONS

It is possible on the day of implant placement surgery to successfully rehabilitate the edentulous atrophic maxilla with a fixed, definitive restoration supported by an intraorally welded titanium framework attached to axial and tilted implants.

Immediate definitive rehabilitation of the edentulous patient using an intraorally welded titanium framework: a 3-year prospective study

OBJECTIVE

The aim of this prospective study was to evaluate the concept of intraoral welding as a suitable technique for the placement of a final restoration in the edentulous patient on the same day as surgery.

METHOD AND MATERIALS

Any patient with a completely edentulous arch who was considered eligible received a fixed restoration supported by an intraorally welded titanium bar. Definitive abutments were connected to the implants and then welded to a titanium bar using an intraoral welding unit. This framework was used to support the definitive acrylic restoration, which was fitted on the same day as implant placement. Restoration and implant success, mean marginal bone loss, pocket probing depth, and bleeding on probing were assessed over a 36-month follow-up period.

RESULTS

Twenty-six patients with an edentulous maxilla and 34 patients with an edentulous mandible, with a mean age of 57.1 years (SD = 17.9, n = 60), were consecutively treated with 324 immediately loaded implants. No fractures or radiographically detectable alteration of the welded framework was evident. A total of 321 (99.1%) implants osseointegrated and were clinically stable at the 6-month follow-up. At the 36-month follow-up, the accumulated mean marginal bone loss was, respectively, 0.967 mm (SD = 0.361) for the maxillary cases and 1.016 mm (SD = 0.413) for the mandibular cases.

CONCLUSIONS

It is possible on the same day of surgery to successfully rehabilitate the edentulous patient with a fixed definitive prosthesis supported by an intraorally welded titanium framework.

A comparison between immediate loading and immediate restoration in cases of partial posterior mandibular edentulism: a 3-year randomized clinical trial

OBJECTIVE

The aim of this study was to compare the survival rate, the bone loss and soft-tissue healing patterns of immediately loaded and immediately restored implants in cases of partial posterior mandibular edentulism.

MATERIAL AND METHODS

Fifty patients with partial posterior mandibular edentulism were randomly selected for two treatments: 25 were included in the immediate loading group (test) and 25 in the immediate restoration group (control). All implants were placed in healed sites with a torque of >25 N cm. The temporary prosthesis of the immediate restoration group was placed so as to avoid occlusal contact in centric and lateral excursions. Both groups received fully occluding final restorations 6 months after surgery. Mean marginal bone loss was assessed at 6-, 12-, 24- and 36-month follow-up examinations by a blinded examiner.

RESULTS

A total of 100 implants were placed in the period between February 2004 and October 2006, of which 42 (42%) were for men and 58 (58%) for women. Five and 7 weeks after surgery, mobility of one implant was assessed in one (4%) patient in the test group and one (4%) patient in the control group, respectively. At the 36-month follow-up, the accumulated mean marginal bone loss was 0.987 mm (SD=0.375) for the immediate restoration group (n=48) and 0.947 mm (SD=0.323) for the immediate loading group (n=48). There was no statistically significant difference (P>0.05) for the tested outcome measures between the two procedures.

CONCLUSIONS

This study was unable to detect any statistically significant difference in the survival rate, bone loss and soft tissue healing patterns between the immediately loaded and the immediately restored implants in cases of partial posterior mandibular edentulism. The immediate temporary rehabilitation of the partially edentulous posterior mandible is a predictable procedure using both procedures.

Immediate rehabilitation of the edentulous mandible with a definitive prosthesis supported by an intraorally welded titanium bar

PURPOSE

The aim of this prospective study was to evaluate the suitability of intraoral welding of implant frameworks to allow placement of the definitive restoration on the same day of surgery.

MATERIALS AND METHODS

Forty patients with an edentulous mandible were planned to be treated with a fixed restoration supported by an intraoral welded titanium bar. Definitive abutments were to be connected to the implants and then welded to a titanium bar using an intraoral welding unit. This framework was to be used as support for the definitive restoration, which was to be placed on the same day as the implants. Mean marginal bone loss and radiographically detectable alterations of the welded framework were to be assessed using periapical radiographs immediately after surgery, and at 6-, 12-, and 24-month follow-up examinations.

RESULTS

Twenty men and 20 women, with a mean age of 47.8 years (+/- 13.9), were consecutively treated with 160 immediately loaded implants. All implants osseointegrated. No fractures or radiographically detectable alterations of the welded frameworks were present. All implants were clinically stable at the 24-month follow-up. Mean marginal bone loss (n = 160 at all time points), assessed using 640 periapical radiographs, was 0.59 +/- 0.12 mm at 6 months, 0.21 +/- 0.051 mm at 12 months, and 0.11 +/- 0.036 mm at 24 months. The accumulated mean marginal bone loss was 0.91 +/- 0.21 mm.

CONCLUSIONS

It is possible to successfully rehabilitate the edentulous mandible on the same day as implant placement surgery with a fixed definitive prosthesis supported by an intraorally welded titanium framework.

One model, several results: the paradox of the Hosmer-Lemeshow goodness-of-fit test for the logistic regression model

BACKGROUND

The Hosmer-Lemeshow test, used extensively to assess the fit of the logistic regression model, is performed by several statistical packages. Recent studies have shown some problems in the use of this test when ties are present. These problems were attributed merely to the test implementation.

METHODS

We analysed the order of the observations as an alternative explanation of the problem of ties. Using a data-set of 1393 intensive care unit (ICU) patients we performed the Hosmer-Lemeshow test with all possible subjects dispositions.

RESULTS

We obtained about one million different P values, ranging from 0.01 to 0.95.

DISCUSSION

It is already known that when the Hosmer-Lemeshow goodness-of-fit test is performed with a number of covariate patterns lower than the number of subjects, its result may be inaccurate. We showed that the extent of this problem could be relevant under particular conditions. We also suggest a strategy for estimating the extent of the problem and subsequent interpretation.

Can airway complications following multilevel anterior cervical surgery be avoided?

OBJECT

The authors conducted a study to determine how to avoid emergency postoperative reintubation and its associated morbidity in patients who have undergone multilevel anterior-posterior cervical spine surgery.

METHODS

In a group effort between the departments of anesthesia and neurosurgery, a protocol was developed to avoid having to reintubate patients postoperatively. As a preventative measure, patients remained intubated overnight; on the 1st postoperative day or thereafter, based on direct fiberoptic visualization of reactive tracheal swelling, an anesthesiologist extubated the patients. Fifty-eight patients underwent multilevel anterior corpectomy with fusion (ACF; with 41 receiving plates and 17 not receiving plates), posterior wiring and fusion (PWF), and application of a halo. On average, ACF involved three levels, whereas PWF included 6.5 levels. Surgery typically lasted 10 hours, and an average 2.6 U of blood was required. Forty patients were successfully extubated on the 1st, five on the 2nd, three on the 3rd, two on the 4th, two on the 5th, and three on the 7th postoperative day. Three elective tracheostomies were performed on the 7th postoperative day. Risk factors associated with delayed extubation or tracheostomy in 18 patients included: operative time longer than 10 hours (12 patients), obesity greater than 220 lbs (12 patients), transfusion of more than 4 U of blood (10 patients), ACF reoperations (nine patients), ACF including C-2 (seven patients), four-level ACF (five patients), and asthma (five patients). In the only case in which emergency reintubation was required, three risk factors were present.

CONCLUSIONS

Emergency reintubation following anterior-posterior cervical surgery and fusion can be avoided by maintaining intubation overnight and subsequently having an anesthesiologist remove the tube after healing is fiberoptically confirmed. Familiarity with major risk factors contributing to airway compromise, combined with this protocol, should minimize the significant morbidity associated with reintubation following multilevel anterior-posterior cervical fusion.

Role of vagus nerve signaling in CNI-1493-mediated suppression of acute inflammation

CNI-1493 is a potent anti-inflammatory agent, which deactivates macrophages and inhibits the synthesis of proinflammatory mediators. The objective of the present study was to identify the role of the central nervous system (CNS) and efferent vagus nerve signaling in CNI-1493-mediated modulation of acute inflammation in the periphery. CNI-1493 was administered either intracerebroventricularly (i.c.v., 0.1-1,000 ng/kg) or intravenously (i.v., 5 mg/kg) in anesthetized rats subjected to a standard model of acute inflammation (subcutaneous (s.c.) injection of carrageenan). I.c.v. CNI-1493 significantly suppressed carrageenan-induced paw edema, even in doses at least 6-logs lower than those required for a systemic effect. Bilateral cervical vagotomy or atropine blockade (1 mg/kg/h) abrogated the anti-inflammatory effects of CNI-1493 (1 microg/kg, i.c.v. or 5 mg/kg, i.v.), indicating that the intact vagus nerve is required for CNI-1493 activity. Recording of the efferent vagus nerve activity revealed an increase in discharge rate starting at 3-4 min after CNI-1493 administration (5 mg/kg, i.v.) and lasting for 10-14 min (control activity=87+/-5.4 impulses/s versus CNI-1493-induced activity= 229+/-6.7 impulses/s). Modulation of efferent vagus nerve activity by electrical stimulation (5 V, 2 ms, 1 Hz) of the transected peripheral vagus nerve for 20 min (10 min before carrageenan administration and 10 min after) also prevented the development of acute inflammation. Local administration of the vagus nerve neurotransmitter, acetylcholine (4 microg/kg, s.c.), or cholinergic agonists into the site of carrageenan-injection also inhibited acute inflammation. These results now identify a previously unrecognized role of efferent vagus nerve activity in mediating the central action of an anti-inflammatory agent.

Unifying Class-Based Representation Formalisms

The notion of class is ubiquitous in computer science and is central in many formalisms for the representation of structured knowledge used both in knowledge representation and in databases. In this paper we study the basic issues underlying such representation formalisms and single out both their common characteristics and their distinguishing features. Such investigation leads us to propose a unifying framework in which we are able to capture the fundamental aspects of several representation languages used in different contexts. The proposed formalism is expressed in the style of description logics, which have been introduced in knowledge representation as a means to provide a semantically well-founded basis for the structural aspects of knowledge representation systems. The description logic considered in this paper is a subset of first order logic with nice computational characteristics. It is quite expressive and features a novel combination of constructs that has not been studied before. The distinguishing constructs are number restrictions, which generalize existence and functional dependencies, inverse roles, which allow one to refer to the inverse of a relationship, and possibly cyclic assertions, which are necessary for capturing real world domains. We are able to show that it is precisely such combination of constructs that makes our logic powerful enough to model the essential set of features for defining class structures that are common to frame systems, object-oriented database languages, and semantic data models. As a consequence of the established correspondences, several significant extensions of each of the above formalisms become available. The high expressiveness of the logic we propose and the need for capturing the reasoning in different contexts forces us to distinguish between unrestricted and finite model reasoning. A notable feature of our proposal is that reasoning in both cases is decidable. We argue that, by virtue of the high expressive power and of the associated reasoning capabilities on both unrestricted and finite models, our logic provides a common core for class-based representation formalisms.

The importance of statistics in documentation on hip prostheses

The authors illustrate the possibilities and the limits of instruments that statistics currently make available in the analysis of a medical series involving hip prosthesis surgery. An analysis of the survival rate constitutes one of the most important tools with regard to data in the study of the effectiveness of implants, but its correct application is influenced by the assumption that so-called censored cases have no differences in survival in relation to those that remain under observation even in periods that follow. Simulation reveals the need to process series with a high number of cases, in order to obtain reliable estimates. Finally, only multivaried techniques allow for a correct evaluation of the incidence that single factors have in causing failure of implants.

Addiction recovery for low-income pregnant and parenting women: a process of becoming

A naturalistic field study of low-income women (N = 17) in an intensive outpatient addiction recovery program addressed the question: What is the nature of addiction recovery for pregnant and parenting-women in an addiction treatment program? Grounded theory methodology was used to determine the nature of the interpersonal and social processes that define addiction recovery for women in this study. Over 2 years, audiotaped semi-structured interviews, document reviews of medical records, treatment progress and group therapy notes, and participant observation notes were collected and analyzed. The constant comparison method of analysis involved an ongoing process of theoretical sampling, memoing, and open and then axial coding to identify, group, link, and reduce the categories produced. A developmental model of addiction recovery in pregnant and parenting women emerged that consisted of the dimensions of becoming drug and alcohol free, a partner in a relationship, a person, and a parent. These four dimensions parallel and transform each other, yielding different outcomes but similar patterns over time. This model of addiction recovery provides a beginning framework for understanding the transactional nature of addiction recovery for low-income women who are adapting to a drug and alcohol-free lifestyle and the task and role of parenting a newborn.

Metal-UHWMPE (Ultra High Molecular Weight Polyethylene) wear: experimental testing

Testing conducted on a hip joint simulator verified the Charnley hypothesis that the diameter of the prosthetic head is proportional to wear. The study was conducted by pairing heads in Ortinox TM with acetabular cups in polyethylene at high molecular weight (UHMWPE). A comparison between the different sizes of the heads (26 and 30 mm in diameter) showed a different trend in the wear rate; in particular, the head with a smaller diameter behaves better tribologically than the head with a larger diameter.

Intraoperative fractures of the femur in prosthetic hip reimplantations

A total of 19 cases of intraoperative fractures of the femoral diaphysis occurring during prosthetic hip reimplantation are described. Incidence, predisposing factors, treatment, and influence on long-term results are discussed. The pre-existence of osteolysis or narrowing of the femoral cortex, often associated with primary cemented implantation with a metal-polyethylene combination, constitutes a factor that predisposes the patient to fracture. Fracture consolidation occurs in most cases with minimum treatment, at times without instrumentation; fracture, however, always means a delay in weight-bearing and a slowing down in recovery times. Long-term clinical evaluation shows functional results that are worse for reimplantations complicated by fracture as compared to those where there are no complications. The differences in the radiographic results instead do not reveal statistical significance.

Breaking ground: combining community service, critical thinking, and writing in a mental health clinical course

This article describes the experience of a team of nursing educators who, over the course of 2 years, redesigned the delivery of an undergraduate nursing clinical course to reflect the changing face of mental health care near the turn of this century. Case studies of student learning experiences show the value of nontraditional clinical settings such as homeless shelters to the professional growth and training of nursing students. Recommendations offer practical advice for combining nontraditional community-based clinical experiences with critical thinking exercises as key components of the mental health clinical course delivery.

[Primary hydatid cyst of the coracobrachial muscle. A clinical case]

Primary localization of hydatidosis in the musculoskeletal system is a quite rare occurrence. We report a case of a 67 year old man with an infestation of the coracobrachialis muscle. We discuss several instrumental and serologic diagnosis methods and the hypothesis of a primary muscular localization.

[Update on laparoscopic surgery: on the treatment of hydatid cyst of the liver and peritonitis caused by a perforated duodenal ulcer]

Laparoscopic surgery represents a real innovation with respect to the traditional laparotomic way of access, owing to its undeniable advantages, both intraoperative and postoperative. This new technique reduces the complications connected with the surgical wound and with forced allerement. Therefore it allows the patient's fast recovery. Laparoscopic surgery application ground get's wider and wider every day: in fact, the authors report two medical cases, one of elective surgery (treatment of a hidatid cyst of the liver) and the other in emergency surgery (peritonitis due to perforated duodenal ulcer), both obtaining a positive result about the clinical and the postoperative timing of recovery.