ΑΝΩ ΓΝΑΘΟΣ j periodontol. 2009 Nov;80(11): 1883-93. Immediate functional loading of dental implants supporting a bar-retained maxillary overdenture: preliminary 12-month results



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Br J Oral Maxillofac Surg. 2009 Nov 11. [Epub ahead of print]

Neutrophil elastase activity and concentrations of interleukin1-beta in crevicular fluid after immediate replacement and immediate loading of implants.

Gruber R, Nadir J, Haas R.

Department of Oral Surgery, Medical University of Vienna, Währingerstrasse 25a,

1090 Vienna, Austria.




Our objective was to calculate the amounts of neutrophil elastase and

interleukin-1beta (IL-1) in the crevicular fluid of dental implants that were

placed and restored immediately after extraction of teeth. The crevicular fluid

of 11 patients was obtained before the teeth were extracted and during the early

(days 1-10) and late (day 10 onwards) follow-up periods. Samples were analysed by

kinetic assay for neutrophil elastase and by immunoassay of IL-1. The absolute

values remained unchanged during the early (p=0.15; p=0.2) and late (p=0.4;

p=0.5) follow-up periods. Paired analysis showed that the absolute values in the

periodontal crevicular fluid were similar compared with the corresponding samples

obtained during the early (p=0.5; p=0.3) and the late (p=0.6; p=0.2) follow-up

periods. These findings suggest that placement of implants according to the

immediate loading protocol, although it is an invasive procedure, does not

provoke an inflammatory reaction.


Int J Oral Maxillofac Implants. 2009 Jul-Aug;24(4):663-71.

Stress patterns around distal angled implants in the all-on-four concept configuration.

Begg T, Geerts GA, Gryzagoridis J.

Department of Restorative Dentistry, University of the Western Cape, Tygerberg,

South Africa.




PURPOSE: The All-on-Four concept advocates immediate loading and the placement of

distal implants at an angle. The purpose of this study was to do a qualitative

descriptive analysis of stress patterns around the distal angled implant of the

All-on-Four concept. MATERIALS AND METHODS: Four photoelastic acrylic resin

models, each with four implants simulating the All-on-Four configuration, were

prepared. The two central implants were placed vertically and parallel in each

model, and the distal implant on each side was placed at an increasing angle (0,

15, 30, and 45 degrees) in each model. The four implants were splinted by means

of a cast metal bar. The photoelastic models were placed between two parallel

anvils. Pairs of abutments were systematically subjected to a load by suspending

5-, 10-, and 15-kg weights from one of the anvils. Photoelastic analysis was

accomplished using a circular polariscope. The fringe patterns produced in the

photoelastic resin for each implant and load were photographed with a digital

camera. Fringe concentrations and the highest fringe order were recorded and

described for the apical, central, and coronal regions of the distal angled

implant for each load scenario. RESULTS: For the implants placed at 15- and



30-degree angles, little difference in stress patterns was observed between the

central straight implant and the distal angled implant. For every load scenario

and for all angulations, the lowest fringe order was recorded at the central

region of the implant. The highest fringe order for the apical region was always

higher than the highest fringe order for the coronal region of the implant.



Markedly increased isochromatic fringe concentrations were observed in model 4,

which had the distal implants placed at a 45-degree angle. CONCLUSION:

Peri-implant bone surrounding the 45-degree-angled distal abutment may be more

prone to occlusal overload than bone surrounding implants with lesser tilts.


J Biomed Mater Res B Appl Biomater. 2009 Nov;91(2):604-12.

Experimental immediate loading of dental implants in conjunction with grafting procedures.

Neugebauer J, Iezzi G, Perrotti V, Fischer JH, Khoury F, Piattelli A, Zoeller JE.

Interdisciplinary Department for Oral Surgery and Implantology, University of

Cologne, Cologne, Germany.


The aim of this study was to evaluate immediate loading (IL) of dental implants

in conjunction with grafting procedures. A total of 107 IL implants were inserted

in six mini pigs. Before implant placement, crestal or apical defects were

created, which were treated with bone chips, phycogene hydroxyapatite (HA),

bovine HA, or bovine HA enhanced with a synthetic peptide. Crestal grafts were

stabilized with titanium membranes. All bridges were in function and showed signs

of chewing wear after 4-month loading. Three out of 107 implants showed no

osseointegration (2.7%). Most of the crestal defects showed incomplete

regeneration, due to an infection of the membranes (74.3%) The difference in

height between surgical and remaining defect was calculated as defect

development, which was 2.3 +/- 2.08 mm for bone chips with an area of regenerated

bone of 22.8 +/- 3.34% and 0.7 +/- 2.22 mm for phycogene HA with 11.3 +/- 4.36%

regenerated bone. Bovine HA showed an increase of defects 1.3 +/- 2.47 mm with

only 7.9 +/- 1.7% bone regeneration. Bovine HA enhanced with a peptide showed a

defect development of 1.1 +/- 1.42 mm with an area of regenerated bone of 18.2

+/- 2.38%. In conclusion, local grafting procedures did not disturb the course of

osseointegration for immediate loaded implants if primary stability was reached.

The regeneration of apical defects was uneventful even with immediate loading.

Crestal defects required membrane fixation with a careful flap elevation to avoid

membrane exposure and loss of the graft.


J Oral Implantol. 2009;35(6):270-6.

Force and movement of non-osseointegrated implants: an in vitro study.

Flanagan D, Ilies H, Lasko B, Stack J.




Abstract Dental implants have enabled a dramatic increase in the quality of life

for many partially edentulous and edentulous patents. Immediate loading of newly



placed dental implants is a recent advancement that attempts to meet patient

demand. However, immediate loading of a just placed implant may induce implant

failure to osseointegrate. Some patients can generate a biting force that can

reach approximately 1300 Newtons (N) in the posterior jaws. The magnitude of bite

force that would cause failure of osseointegration of newly placed implants is

currently unknown. It has been proposed that osseointegration would fail if an

implant is luxated in bone more than 50 to 150 microns. Fibrous tissue, not bone,

would form. This study investigated the quantity of various off-axial forces

required to move a nonosseointegrated 4.3 x 13 mm implant 50 microns. The

previously published pilot study for this study found that the amount of

horizontal force required to displace an implant 50 microns was approximately 150

N. This study found that the force needed to move the implants 100 microns at a

horizontal approach, 0 degrees, averaged 50 N, with a range of 23-79 N; at 22

degrees, averaged 52 N, with a range of 27-70 N; and at 60 degrees averaged 87 N,

with a range of 33-105 N.


Implant Dent. 2009 Apr;18(2):162-71.

Human ex vivo bone tissue strains around immediately-loaded implants supporting mandibular fixed prostheses.

Kökat AM, Cömert A, Tekdemir I, Akkocaoğlu M, Akça K, Cehreli MC.

Department of Prosthodontics, Yeditepe University, Goztepe, Istanbul.


PURPOSE: The purpose of this study was to qualify and quantify bone strains

around immediately-loaded implants supporting mandibular fixed prostheses with

regard to number of implant support. MATERIALS: Linear strain gauges were bonded

on the labial bone of 5 Straumann dental implants placed in the mandibular

symphysis region of 2 completely edentulous mandibles of fresh human cadavers.

Installation torque value of each implant was measured by a custom-made torque

wrench and resonance frequency analyses were undertaken. A one-piece full-arch

fixed prosthesis was fabricated for each cadaver and 2 miniature load cells were

integrated in the cantilever region of the prostheses for controlled loading

experiments. 5-, 4-, and 3-implant support designs were consecutively tested.

Strain measurements were performed at a sample rate of 10 KHz and under a maximum

load of 100 N, simultaneously monitored from a computer connected to data

acquisition system. RESULTS: The installation torque values and implant stability

quotient values of the implants ranged between 42.12 to 145.67 N cm and 61 to 80,

respectively. Between-group comparisons revealed that the highest strain

magnitudes were recorded for the 3-implant design followed by the 4- and

5-implant designs, although there was a tendency toward similar load partitioning

between 4- and 5-implant designs (P < 0.05). CONCLUSIONS: Bone strains around



3-implant supported mandibular fixed prostheses is significantly higher than

those around 4- and 5-implant designs, and this may lead to failure of supporting

implants. Four- and 5-implant designs might have similar clinical outcome.


Med Oral Patol Oral Cir Bucal. 2009 Feb 1;14(2):E93-7.

In vitro evaluation of the influence of the cortical bone on the primary stability of two implant systems.

Andrés-García R, Vives NG, Climent FH, Palacín AF, Santos VR, Climent MH, Bullón

P.

Faculty of Dentistry, University of Seville, Spain. randresgarcia@gmail.com




AIMS: Immediate loading has become a predictable option for treatment, while one

of the main requirements for its implementation is obtaining appropriate primary

stability in implants. With that aim, conical implants are commercially

available, since, according to specialized literature, they provide greater

stability. One of the methods to measure implant stability which has evolved to

further stages is resonance frequency analysis (RFA). In the present paper we

attempt to evaluate the influence of the cortical bone on the primary stability

of two implants of similar diameter and length. STUDY DESIGN: 15 fresh cow ribs

were selected and six different implant beds were prepared in each. These

preparations corresponded to two different implant systems: A Swiss Plus from

Zimmer Dental and an Mk IV from Nobel Biocare. Two drilling protocols were used

for soft bone, hard bone and bone without cortical. After preparing the beds, the

implants were placed and implant primary stability was measured with the Osstell

mentor. RESULTS: Higher ISQ (Implant Stability Quotient) values were observed for

both implant systems when the cortical bone is maintained than when it is

eliminated, the difference being statistically significant in the case of Mk IV

implants. CONCLUSIONS: The results from this study show the importance of

preserving cortical bone during drilling in order to obtain greater primary

stability.


Clin Implant Dent Relat Res. 2009 Sep 9. [Epub ahead of print]

The Effects of Superficial Roughness and Design on the Primary Stability of Dental Implants.

Dos Santos MV, Elias CN, Cavalcanti Lima JH.

Biomaterials Laboratory, Instituto Militar de Engenharia, Rio de Janeiro, RJ,

Brazil;


ABSTRACT Background: Primary implant stability has been used as an indicator for

future osseointegration and whether an immediate/early loading protocol should be

applied. Implant stability is the key to clinical success. Purpose: The aim of

this work was to analyze the influence of the design and surface morphology on

the primary stability of dental implants. The insertion torque and resonance

frequency analysis (RFA) were the parameters used to measure the primary

stability of the implants. Materials and Methods: Thirty implants, divided in six

groups of five samples were placed in cylinder of high molecular weight

polyethylene. The groups were different upon two designs (cylindrical and conic)

and three implant surfaces finishing (machined, acid etched, and anodized). The

insertion torque was quantified by a digital torque driver (Lutron Electronic

Enterprise Co., Taipei, Taiwan) and the resonance frequency was measured by

Osstell mentor (Integration Diagnostics AB, Göteborg, Sweden). The implant

surface morphology was characterized by scanning electron microscopy, roughness

measurement, and friction coefficient. Results: The machined implants showed

smaller insertion torques than treated implant surfaces. There were no

differences between the RFA measurements in all tested surfaces. Statistical

analyses demonstrated no correlation between the dental implant insertion torque

and primary stability measured by the RFA. The implants with treated surfaces

showed greater roughness, a higher friction coefficient, and demanded a larger

insertion torque than machined implants. The results of the surface roughness and

friction coefficients are in accordance with the results of the insertion torque.

The difference, across the insertion torque values, between conical and

cylindrical implants, can be explained by the different contact surface area

among the thread geometry of these implants. Conclusion: The maximum implant

insertion torque depends on the implant geometry, thread form, and implant

surface morphology. The placement of conical implants with treated surfaces

required the highest insertion torque. There was no correlation between RFA and

insertion torque implant.


Clin Oral Implants Res. 2009 May;20(5):467-71.

Implant micromotion is related to peak insertion torque and bone density.

Trisi P, Perfetti G, Baldoni E, Berardi D, Colagiovanni M, Scogna G.

Laboratory of Biomaterials and Biomechanics, Galeazzi Orthopaedic Institute,

University of Milano, Milano, Italy. paulbioc@tin.it


OBJECTIVES: Measuring peak insertion torque in relation to different bone

densities, the present study seeks to determine whether micromotion at the

interface is related to primary stability achieved by increasing insertion

torque. MATERIAL AND METHODS: A total of 120 Ti-Bone implants were placed in

fresh bovine bone samples representing three density categories: hard, normal and

soft (HNS). Five groups of peak insertion torque (20, 35, 45, 70 and 100 N/cm)

were evaluated in the three bone density categories noted. Customized electronic

equipment connected to a PC was used to register the peak and other insertion

torque data. A loading device, consisting of a digital force gauge and a digital

micrometer, was used to measure the micromovements of the implant during the

application of 20, 25 and 30 N lateral forces. The data were analyzed for

statistical significance by ANOVA and Spearman's rank correlation coefficient

tests. RESULTS: A statistically significant difference between implant

micromobility placed with different levels of torque and in different bone

densities was demonstrated by ANOVA. Spearman's rank correlation coefficient

showed a high dependency between the peak insertion torque and the observed

micromovement. Particularly, in soft bone, it was not possible to achieve more

than 35 N/cm of peak insertion torque. CONCLUSIONS: Results showed that



increasing the peak insertion torque reduces the level of implant micromotion. In

addition, micromotion in soft bone was found to be consistently high, which could

lead to the failure of osseointegration. Thus, immediate functional loading of

implants in soft bone should be considered with caution.

Minerva Stomatol. 2009 Jun;58(6):263-75.

Histomorphometric evaluation of implant design as a key factor in peri-implant bone response: a preliminary study in a dog model.

[Article in English, Italian]

Orsini E, Salgarello S, Bubalo M, Lazic Z, Trire A, Martini D, Franchi M, Ruggeri

A.

Department of Human Anatomy, University of Bologna, Bologna, Italy.



ester.orsini@unibo.it


AIM: Primary implant stability as the establishment of a direct bone-to-implant

contact (BIC) plays a major role in long-term successful implant

osseointegration. Numerous factors influencing this initial stability have been

studied. This preliminary in vivo study on a dog lower jaw aimed to investigate

the hypothesis that primary implant stability in low density bone may be

influenced by implant design. METHODS: The authors compared two different implant

designs with regard to their immediate quantitative relation to host bone (BIC%

and gap area, GA%). The screw-shaped implants, manufactured by Or-Vit



(Castelmaggiore-Bologna, Italy), exhibited similar microroughness surface and two

different thread pitches: ''narrow-pitch'' implants (NP) and ''wide-pitch''

implants (WP) with a 0.5 mm and 1.5 mm thread pitch respectively. Implants were

placed in dog jaw after complete osseous healing of the extractive sockets,

according to a delayed implantation procedure. Five hours after surgery the

animal was sacrificed. Radiographic, histological, morphometric and

ultrastructural analysis were performed. RESULTS: An inverse relation existed

among the two parameters BIC and GA: GA, as a region with high osteogenetic

potentiality, appeared wider in WP implants; BIC, as the expression of primary

mechanical stability, was higher in NP implants. CONCLUSION: Based on this



results, we could assume that NP implants might be the clinical choice in case of

immediate loading.This single case study might be considered a starting point for

further long term in vivo investigations aiming to establish the implant design

that best favours osseointegration at different bone quality sites.



Clin Oral Implants Res. 2009 Feb;20(2):126-34.

Early cortical bone healing around loaded titanium implants: a histological study in the rabbit.

Slaets E, Naert I, Carmeliet G, Duyck J.

Department of Prosthetic Dentistry, BIOMAT Research Group, K.U., Leuven, Belgium.


OBJECTIVES: To identify the role of immediate implant loading on the early phases

of the bone healing responses. MATERIAL AND METHODS: Implants were placed in

rabbit tibial diaphyses and left to heal for 3, 7, 14, 28 or 42 days. Half of the

animals received an immediate loading protocol of 2.2 N at 3 Hz for 1800 cycles

and 5 days/week, whereas the others served as unloaded controls. Histological

assessment was combined with histomorphometrical measurements. RESULTS: At early

time-points, an endosteal and periosteal new bone formation was found, while the

cortex itself contained damaged osteocytes. At later time-points, new bone

formation was also found at the cortical level itself. Differences between groups

were found mainly in this new bone formation process, with larger reactions for

the endosteal and periosteal bone in the loaded group after 28 and 42 days,

respectively. At the end-point of the experiment, bone formation at the cortical

level was reduced in the loaded group compared with the control group.

CONCLUSIONS: These results show that the immediate loading protocol caused no



differences in the sequential events leading to osseointegration in cortical

bone. However, the processes of new bone formation originating from the endosteum

and the periosteum lasted longer compared with the unloaded controls.


J Prosthodont. 2009 Jul;18(5):393-402. Epub 2009 Apr 3.

Implant-bone interface stress distribution in immediately loaded implants of different diameters: a three-dimensional finite element analysis.

Ding X, Zhu XH, Liao SH, Zhang XH, Chen H.

Department of Stomatology, The First Affiliated Hospital of Wenzhou Medical

College, Wenzhou, Zhejiang Province, China. dingxi@hosp1.ac.cn




PURPOSE: To establish a 3D finite element model of a mandible with dental

implants for immediate loading and to analyze stress distribution in bone around

implants of different diameters. MATERIALS AND METHODS: Three mandible models,

embedded with thread implants (ITI, Straumann, Switzerland) with diameters of

3.3, 4.1, and 4.8 mm, respectively, were developed using CT scanning and

self-developed Universal Surgical Integration System software. The von Mises

stress and strain of the implant-bone interface were calculated with the ANSYS

software when implants were loaded with 150 N vertical or buccolingual forces.

RESULTS: When the implants were loaded with vertical force, the von Mises stress

concentrated on the mesial and distal surfaces of cortical bone around the neck

of implants, with peak values of 25.0, 17.6 and 11.6 MPa for 3.3, 4.1, and 4.8 mm

diameters, respectively, while the maximum strains (5854, 4903, 4344 muepsilon)

were located on the buccal cancellous bone around the implant bottom and threads

of implants. The stress and strain were significantly lower (p < 0.05) with the

increased diameter of implant. When the implants were loaded with buccolingual

force, the peak von Mises stress values occurred on the buccal surface of

cortical bone around the implant neck, with values of 131.1, 78.7, and 68.1 MPa

for 3.3, 4.1, and 4.8 mm diameters, respectively, while the maximum strains

occurred on the buccal surface of cancellous bone adjacent to the implant neck,

with peak values of 14,218, 12,706, and 11,504 microm, respectively. The stress

of the 4.1-mm diameter implants was significantly lower (p < 0.05) than those of

3.3-mm diameter implants, but not statistically different from that of the 4.8 mm

implant. CONCLUSIONS: With an increase of implant diameter, stress and strain on

the implant-bone interfaces significantly decreased, especially when the diameter

increased from 3.3 to 4.1 mm. It appears that dental implants of 10 mm in length

for immediate loading should be at least 4.1 mm in diameter, and uniaxial loading

to dental implants should be avoided or minimized.


Implant Dent. 2009 Apr;18(2):142-50.

Immediate loading of modified acid etched dental implants in postextraction sockets: a histological and histomorphometrical comparative study in nonhuman

primate Papio ursinus.

Mangano C, Piattelli A, Mangano F, Perrotti V, Iezzi G.

Dental School, University of Varese, Italy.


PURPOSE: Immediate loading of dental implants inserted into fresh postextraction

sites has recently been proposed as a novel but challenging surgical approach.

However, histological evidence and comparative data are still missing. The aim of

this study was an histological and histomorphometrical comparison of submerged

and immediately loaded dental implants with a new modified acid etched surface

inserted into postextraction sites of nonhuman primates. MATERIALS AND METHOD:

Thirty-two implants were placed in postextraction sockets of 4 adult Chacma

Baboons (papio ursinus). Each baboon received 8 implants: 4 submerged and 4

immediately loaded. The implants were retrieved after 90 days of healing with a

4-mm trephine bur and processed for histology and histomorphometry. RESULTS: The

bone-to-implant contact percentage in the submerged and immediate loaded implants

was 86.02% and 86.85%, respectively, with no statistically significant

differences. In the immediately loaded implants a greater amount of ongoing

remodeling was observed. CONCLUSIONS: Immediate loading seemed to be a valid

alternative to conventional technique when a implant is inserted into

postextraction sockets. Further comparative studies on a greater number of

samples are necessary to confirm our findings.





ΑΛΛΕΣ ΕΡΓΑΣΙΕΣ





J Craniofac Surg. 2009 Nov;20(6):2139-42.

Clinical viability of immediate loading of dental implants: part I--factors for success.

Goiato MC, Pellizzer EP, dos Santos DM, Barão VA, de Carvalho BM, Magro-Filho O,

Garcia IR Jr.

UNESP--Araçatuba Dental School, Dental Materials and Prosthodontics, José

Bonifácio, 1193, Araçatuba, São Paulo 16015-050, Brazil. goiato@foa.unesp.br




Two-stage procedure for dental implants presents corroborated clinical success

over 40 years. The evolution of surgical techniques, development of diagnostic

methods, knowledge about tissue biology, and quality of implants regarding design

and surface supported studies with 1 surgical stage followed by immediate

prosthesis placement. However, several factors influence the treatment success

with immediate loading. So, this study aimed to evaluate some factors regarding



the success and characteristics of implants and patients.


Implant Dent. 2009 Jun;18(3):203-9.

Bone quality and the immediate loading of implants-critical aspects based on literature, research, and clinical experience.

Romanos GE.

Division of Periodontology, Eastman Department of Dentistry, University of

Rochester, Rochester, NY 14620, USA. Georgios_Romanos@urmc.rochester.edu


Immediate loading of oral implants has been extensively described in the

international literature and the requirements for long-term success are



evaluated. The author presents here the critical aspects of the criteria for

success as well as describes the characteristics of an implant macro- and

microdesign for immediate loading to control the periimplant crestal bone loss

and secure the long-term stability. Information from the literature and the

clinical experience will be presented.




Αθήνα, 03 / 01 / 2010





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