Immediate Loading of Mandibular
Overdentures Supported by Unsplinted
Direct Laser Metal-Forming Implants:
Results From a 1-Year Prospective
Study
Carlo Mangano,* Francesco G. Mangano,
†Jamil A. Shibli,
‡Massimiliano Ricci,
§Vittoria Perrotti,
iSusana d’Avila,
¶and Adriano Piattelli
iBackground: At present, only some studies have dealt with im-mediate loading of unsplinted implants supporting mandibular overdentures. The aim of this prospective study is to evaluate treatment outcomes of mandibular overdentures supported by four one-piece, unsplinted, immediately loaded, direct laser metal-forming (DLMF) implants by assessing implant sur-vival rate, implant success, marginal bone loss, and prosthetic complications.
Methods: A total of 96 one-piece DLMF implants were inserted in the edentulous mandible of 24 patients. Four implants were placed in each edentulous mandible. Immediately after implant placement, a mandibular overdenture was connected to the implants. At 1-year follow-up, clinical, radiographic, and prosthetic parameters were assessed. Success criteria included absence of pain, suppuration, and implant mobility; absence of continuous peri-implant radiolucency; and distance between the implant shoulder and the first visible bone contact <1.5 mm. Results: After a 1-year loading time, the overall implant sur-vival rate was 98.9%, with only one implant lost. Among the surviving 95 implants, two did not fulfill the success criteria; therefore, the implant success rate was 97.8%. The mean dis-tance between the implant shoulder and the first visible bone contact was 0.28 – 0.30 mm (95% confidence interval, 0.24 to 0.32). Some prosthetic complications were reported.
Conclusion: Based on the present results and within the limits of this study, the immediate loading of four unsplinted DLMF im-plants by means of ball attachment–supported mandibular over-dentures seems to represent a safe and successful procedure. J Periodontol 2012;83:70-78.
KEY WORDS
Dental implantation, endosseous; denture, implant-supported; immediate dental implant loading.
C
omplete denture wearers are usu-ally able to wear an upper denture without problems, but edentu-lous patients with a severely resorbed mandible often experience problems with conventional dentures, such as in-sufficient stability and retention during masticatory function.1,2This insufficient stability can represent a serious problem on a daily basis, with inability to commi-nute foods, decreased self-confidence, and decreased quality of life and social contact.3 In the anatomicallyunfavor-able situation of an edentulous mandible, and for patients who are lacking stability and retention of their complete denture, implant-supported overdenture is a pos-sible treatment option to ensure adequate prosthetic rehabilitation.2-4 An overden-ture provides stability of the prosthesis,1-6 and patients are able to reproduce a determined centric occlusion. Evidence indicates that implant-retained overden-tures significantly increase objective chew-ing ability4-6 and occlusal force.4-6 This
results in an increase of subjective patient satisfaction3-6 and potential
im-provement in the oral health-related qual-ity of life.6
Clinical follow-up studies have re-ported good and predictable long-term
* Department of Biomaterials, Dental School, University of Varese, Varese, Italy. † Private practice, Gravedona (Como), Italy.
‡ Dental Research Division, Department of Periodontology and Oral Implantology, Guarulhos University, Guarulhos, Sa˜o Paulo, Brazil.
§ Nanoworld Institute, University of Genoa, Genoa, Italy.
i Department of Oral Pathology and Oral Medicine, Dental School, University of Chieti-Pescara, Chieti, Italy.
¶ Private practice, Guarulhos, Sa˜o Paulo, Brazil.
clinical and prosthetic outcomes with implant-sup-ported mandibular overdentures.7-10
A variety of attachment systems have been used to retain the overdenture, such as bar and ball attach-ments and locator and magnet attachattach-ments. In gen-eral, these systems are divided into two major categories: splinted and non-splinted.11 The use of two to four implants connected with a bar seems to dominate the literature,11although the use of two to four unsplinted implants has been reported to be a fea-sible option.12The advantages of the latter technique
are simplicity and low costs.11,12
Implants are usually left to heal unloaded for ‡3 months to obtain osseointegration,13but this healing
period may cause some discomfort to patients be-cause of the instability of the provisional dentures. Shortening treatment time can be achieved with one-stage surgery and immediate loading of dental implants.13,14 Immediate loading of mandibular im-plant overdentures is a protocol proposed in 1979, in which four titanium implants were placed in the in-terforaminal area of the mandible and immediately loaded with a bar-supported overdenture.15The rigid connection of three to four interforaminal implants with a U-shaped curved Dolder bar can limit move-ment or non-axial load on implants, also in the case of immediate loading with an overdenture. In this sit-uation, osseointegration can take place normally.15
However, only some studies have dealt with the im-mediate loading of unsplinted implants supporting mandibular overdentures.14-20 It can be
hypothe-sized that unsplinted implants may be negatively af-fected by immediate loading because the load is not shared between implants.14-20
Until now, dental implants have been produced by machining titanium rods, with subsequent post-fabrica-tion processing and applicapost-fabrica-tion of surface treatments or coatings, with the aim to promote osseointegration.21-23 Over the last years, a considerable number of surface modifications, such as sandblasting, acid-etching, grit-blasting, anodization, discrete calcium-phosphate crys-tal deposition, coatings with biologic molecules, and chemical modification have been introduced to obtain microrough and nanorough implant surfaces.23-26All
the traditional methods used for manufacturing and pro-cessing dental implants, however, result in a high-den-sity titanium structure with a microrough or nanorough surface; using these methods, it is not possible to fabri-cate implants with a functionally graded structure, pos-sessing a gradient of porosity perpendicular to the long axis, a relatively high porosity at the surface, and a high density in the core.23-26
In recent years, considerable progress has been made in the development of rapid prototyping methods, including direct laser metal-forming (DLMF).21-23 DLMF is a timesaving metal-forming
procedure in which a high-power laser beam is di-rected on a metal powder bed and programmed to fuse particles according to a computer assisted design (CAD) file, thus generating a thin metal layer. Appo-sition of subsequent layers gives shape to a desired three-dimensional form with minimal post-processing requirements.21-23 With DLMF, it is now possible to fabricate dental implants with different shapes and textures, directly from CAD models.21-23 Laser-forming methods allow the fabrication of functionally graded titanium implants, with a gradient of porosity perpendicular to the long axis.21-23 Moreover, with
DLMF, a porous surface structure for bone ingrowth is provided.21-23The chemical and physical
proper-ties of dental implants created with the DLMF tech-nique have been investigated.21-23 The biologic
response to the DLMF implant surface has been inves-tigated in different in vitro studies in which human fi-brin clot formation23 and the behavior of human osteoblasts23 and mesenchymal stem cells24 were analyzed. The biologic behavior of DLMF implants has been investigated in vivo in histologic and histo-morphometric studies in humans.25,26
The aim of the present 1-year prospective study is to evaluate treatment outcomes of mandibular over-dentures supported by four one-piece, unsplinted, immediately loaded DLMF implants, by assessing implant survival rate, implant success, marginal bone loss, and prosthetic complications.
MATERIALS AND METHODS
Between April and September 2009, a total of 28 pa-tients (18 males and 10 females; aged 47 to 73 years; mean age: 61.6 years) presenting complete mandib-ular edentulism and having functional problems with a complete denture were considered prosthetic reha-bilitation by means of implant-retained mandibular overdentures at the University of Varese, Varese, Italy. Patient inclusion criteria were: 1) total edentulism in the mandible for ‡6 months before implant place-ment; 2) functional problems (e.g., lack of stability and discomfort); 3) sufficient mandibular bone vol-ume in the interforaminal area to place implants ‡2.7 mm in diameter and 10 mm in length; and 4) ad-equate oral hygiene.
Patient exclusion criteria were: 1) heavy smoking habit (>15 cigarettes per day); 2) uncontrolled diabe-tes; 3) metabolic bone disorders; 4) previously re-ceived local radiotheraphy to the head and neck region for malignancies; 5) undergoing antiblastic chemotherapy; and 6) neurologic diseases.
Four patients were excluded, two for insufficient bone volume, and two for heavy smoking habit. Twenty-four patients (14 males and 10 females; aged 57 to 73 years; average age: 63.6 years) were en-rolled. All the patients were thoroughly informed
about the study and each signed a written informed consent form. The study was performed according to the principles outlined in the World’s Medical Asso-ciation’s Declaration of Helsinki on experimentation involving human subjects, as revised in 2008, and ap-proved by the Local Ethics Committee for Human Studies at the University of Varese.
Preoperative Work-Up
A complete examination of the oral hard and soft tis-sues was carried out for each patient. Preoperative work-ups included an assessment of the edentulous mandible using casts and diagnostic wax-up. Pano-ramic radiographs and computed tomography (CT) scans were taken. CT datasets were acquired using a modern cone-beam scanner and then transferred in the appropriate format#to specific implant
naviga-tion software to perform a three-dimensional recon-struction of the mandible. Through this navigation software, it was possible to correctly assess the width of each implant site, the thickness and the density of the cortical plates and the cancellous bone, and the ridge angulation. Bone density was also assessed to obtain a reliable and valid description of preoperative jawbone condition.
DLMF Implants
Ninety-six screw-type one-piece implants (Fig. 1) were manufactured with a DLMF technique.**21,23
The DLMF implants were made of master alloy pow-der (Ti-6Al-4V), with a particle size of 25 to 45 mm, as the basic material. Processing was carried out in an argon atmosphere using a powerful ytterbium fi-ber laser system††with the capacity to build a vol-ume £250 · 250 · 215 mm using a wavelength of 1,054 nm with a continuous power of 200 W, at a scanning rate of 7 meters per second. The size of the laser spot was 0.1 mm. To remove residual par-ticles from the manufacturing process, the sample was sonicated for 5 minutes in distilled water at 25C, immersed in sodium hydroxide (20 g/L) and hy-drogen peroxide (20 g/L) at 80C for 30 minutes, and then further sonicated for 5 minutes in distilled water. Acid etching was carried out by immersion of the sam-ples in a mixture of 50% oxalic acid and 50% maleic acid at 80C for 45 minutes, followed by washing for 5 minutes in distilled water in a sonic bath (Fig. 2).21,23The surface topography of the DLMS had no clear orientation. The direct laser preparation pro-vided an implant surface with a roughness surface with the mean – SD of the absolute values of all profile points, the root-mean-square of the values of all points, and the average value of the absolute heights of the five highest peaks and the depths of the five deepest valleys of 66.8 – 6.6 mm, 77.6 – 11.1 mm, and 358.3 – 101.9 mm, respectively.
Implant Placement
Local anesthesia was obtained by infiltrating articaine 4% containing 1:100.000 adrenaline.‡‡An extended
crestal incision was made, with or without releasing incisions, and full-thickness flaps were elevated ex-posing the alveolar ridge. When indicated, a flattening of the alveolar crest was performed with a bur, under irrigation with sterile saline, to obtain a larger and flat bony base. Four one-piece DLMF implants were placed in each edentulous mandible, for a total of 96 implants inserted over a 4-month period (April to September 2009). The preparation of implant sites was carried out with twist drills of increasing diameter (2 mm for a 2.7-mm diameter; and 2.6 mm for a 3.2-mm diameter), under constant irrigation. Implants were positioned at the bone crest level in the lateral in-cisor and in the first premolar area. A manual surgical Torque wrench was used to measure the peak inser-tion torque (>70 Ncm). The inserinser-tion torque was high because the porous surface of DLMF implants is char-acterized by a high coefficient of friction. Care was taken to assess the position of the mental foramen. The flaps were repositioned and were secured around the implants by interrupted sutures.§§
Prosthodontic Procedure
Immediately after implant surgery, the provisional mandibular denture was seated in the patient’s mouth and adjusted with relieving base acrylic resin to provide clearance in the area of the ball attachments. T h e o c c l u s i o n w a s c h e c k e d , t h e n r e s i l i e n t attachmentsii were positioned on the ball attach-ments, directly in the patient’s mouth, and inglobated in the patient’s provisional denture with soft acrylic resin. Denture stability, retention, and occlusion were checked, and the patients received postoperative in-structions. Patients were instructed not to remove the overdenture for 24 hours to minimize swelling. After 2 weeks, impressions were taken, and the laboratory proceeded with the fabrication of the definitive pros-thesis. All the definitive dentures were fabricated by acrylic resin with a metal framework, and were deliv-ered to the patients 4 weeks after implant placement. Resilient attachments¶¶ were inglobated in the hard
acrylic resin structure. All overdentures were carefully evaluated for proper occlusion, and protrusion and laterotrusion were assessed on the articulator and intraorally, to secure a balanced occlusion in centric relation without anterior tooth contact.
#
DICOM National Electrical Manufacturers Association, Rosslyn, VAC. ** TixOs Nano Ovd, Leader-Novaxa, Milan, Italy.
†† Eos Laser Systems, Munich, Germany. ‡‡ Ubistesin, 3M Espe, St. Paul, MN. §§ Supramid, Novaxa, Milan, Italy. ii Oti-Cap, Rhein 83srl, Bologna, Italy. ¶¶ Oti-Cap, Rhein 83srl.
Postoperative Treatment
All patients received oral antibiotics, amoxicillin plus clavulanic acid,##2 g each day for 6 days.
Postoper-ative pain was controlled by administering 100 mg nimesulide*** every 12 hours for 2 days, and detailed instructions about oral hygiene were given, including mouthrinses with 0.12% chlorhexidine††† adminis-tered for 7 days. Suture removal was performed at 8 to 10 days post-surgery.
Clinical, Radiographic, and Prosthetic Evaluation The following clinical parameters were investigated after 1 year of functional loading for each implant: 1) presence and absence of pain;8 2) presence and
absence of suppuration or exudation; and 3) presence and absence of implant mobility, tested manually us-ing the handles of two dental mirrors.
Intraoral periapical radiographs were taken for each implant, using an alignment system with a rigid film-ob-ject x-ray source coupled to a beam-aiming device to achieve reproducible exposure geometry.8Customized
positioners, made of polyvinyl siloxane, combined with an alignment system with a rigid film-object x-ray source coupled to a beam-aiming device, were used for precise repositioning and stabilization of the radio-graphic template. Radiographs were taken at the base-line (immediately after implant insertion) and at the 1-year follow-up session to evaluate the presence or absence of continuous peri-implant radiolucencies and to measure the distance between the implant shoulder and the first visible bone contact (DIB) in mil-limeters at the mesial and distal implant site,8 by
means of an ocular grid. For the second measurement,
crestal bone level changes were recorded as changes in the vertical dimension of the bone around the im-plant, so that an evaluation of peri-implant crestal bone stability was obtained over time. To correct for sional distortion in the radiograph, the apparent dimen-sion of each implant (directly measured on the radiograph) was compared to the true implant length, and the following equation:
RadiographicðRxÞ implant length: True implant length = Rx DIB : True DIB was used to establish, with adequate precision, the amount of vertical bone loss at the mesial and distal site of the implant.
Finally, at the 1-year follow-up session, prosthesis function was tested. Static and dynamic occlusion was evaluated, using standard occluding papers. Careful attention was dedicated to the analysis of prosthetic complications, such as acrylic resin or tooth (denture) fractures. Moreover, prosthetic main-tenance (e.g., the need for reactivation of retentive caps and substitution or replacement of the matrix cap) was taken into account.
Implant Survival and Implant Success Criteria The evaluation of implant survival and implant suc-cess was performed according to the following clinical and radiographic parameters.27 Implants were
di-vided into two categories: 1) survived implants; and 2) failed implants. A survived implant was classified as such when it was still functional at the end of the study, after 1 year of functional loading. Implant los-ses were categorized as failures. Implants presenting pain on function, suppuration, or clinical mobility were removed and categorized as failures. The condi-tions for which implant removal could be indicated included failure of osseointegration or infection, re-current peri-implantitis, or implant loss caused by mechanical overload.
To achieve implant success, the following clinical and radiographic success criteria had to be fulfilled:27
1) absence of pain on function; 2) absence of suppu-ration or exudation; 3) absence of clinically detectable implant mobility; 4) absence of continuous peri-im-plant radiolucency; and 5) DIB <1.5 mm after 12 months of functional loading.27
RESULTS
Implant Survival
Ninety-six implants were inserted in 24 patients. The distribution of the implants by length and diameter is shown in Table 1. No patients dropped out of this
Figure 1.
Schematic drawing of the one-piece DLMF implant.
## Augmentin, GlaxoSmithkline Beecham, Brentford, UK. *** Aulin, Roche Pharmaceutical, Basel, Switzerland. ††† Chlorexidine, OralB, Boston, MA.
study and all implants were examined at the 1-year re-call. At the end of the study, the overall implant sur-vival rate was 98.9%, with 95 implants still in function. One implant failed (1 month after place-ment) and was removed. This failure was attributed to lack of osseointegration without clinical signs of peri-implant infection.
Implant Success
Ninety-five implants were still in function at the end of the study; 93 (97.8%) were classified in the implant success group. None of these implants showed pain or clinical mobility, suppuration, or exudation, with a DIB <1.5 mm. Two implants (2.1%) were not classi-fied in the success group: one (1%) had a history of ex-udation, with some pain on function; and the other (1%) showed a mean DIB of 1.9 mm, associated with deep (6 mm) periodontal probing. The overall radio-graphic evaluation of the implants revealed a mean DIB of 0.28 – 0.30 mm (95% confidence interval, 0.24 to 0.32; range, 0.0 to 1.9 mm) at the 1-year ex-amination (Figs. 3 through 7).
Prosthetic Complications and Maintenance
Prosthetic complications included the result of cracked or fractured dentures (one patient, 4.1%) and loose or lost denture teeth (one patient, 4.1%). Reline of two dentures was required (8.3%). The most common maintenance need was replacement of the retentive caps in the denture base, which is normally required every 18 months (Table 2).
DISCUSSION
Today, immediate loading of mandibular implant overdentures using four splinted implants is a scien-tifically and clinically validated protocol, and a num-ber of studies have concluded that overall implant success had not been adversely affected by immedi-ate loading.14-16
Recently, immediate loading of mandibular over-dentures using unsplinted implants has been intro-duced.17-20 In a prospective study on immediate
loading of overdentures supported by two unsplinted implants with ball attachment connection, Ormianer et al.16found an implant survival rate of 96.4%, with
minimal bone loss around implants. In another study, Marzola et al.17 proposed the immediate loading of
two implants by means of a ball attachment–retained mandibular denture, and concluded that this ap-proach may become a predictable treatment option, with no implant failure (implant survival rate, 100%) and an average DIB of 0.7 – 0.5 mm. In a similar 2-year study on mandibular overdentures, Stephan et al.18 reported a 100% implant survival rate with three free-standing implants immediately loaded with a ball attachment. Within its limits (e.g., the limited follow-up) the present prospective study seems to
confirm these findings, with an implant survival rate of 98.9% and an average DIB of 0.28 – 0.30 mm at the 1-year examination. The results of these studies support the concept that two to four unsplinted im-plants in the interforaminal area can satisfactorily support an immediately loaded implant overden-ture.17-19Still, prospective controlled studies
com-paring the outcome of the immediate loading of mandibular overdentures with different number of implants are missing.14,15
The true benefit of any treatment can only be prop-erly evaluated when compared to a reference group, but the higher implant failure percentages showed that one-implant supported restorations could be re-lated to the use of a single implant to support the prosthetic rehabilitation.20 With immediate loading protocols, implant-related factors (number and distri-bution of the implants, implant length and diameter, design, taper, and surface), surgical technique (prep-aration of the osteotomy), and patient variables (bone quantity and quality, health condition, smoking habit,
Figure 2.
Scanning electron microscopy of the implant surface. The implant has an irregular surface with ridge-like and globular protrusions, interspersed by intercommunicating pores and irregular crevices. The alternation of rounded features, narrow crevices, and deep indents is particularly evident. (original magnification ·250).
Table 1.
Distribution of the Implants by Length and
Diameter (mm)
Implant Diameter Implant Length 10 11.5 13 16 Total 2.7 6 8 22 5 41 3.2 8 18 24 5 55 Total 14 26 46 10 96and bruxism) are important factors for the final out-come.28 It is believed that predictable results with
immediate loaded implants might be possible if suffi-cient primary stability could be achieved.28For this
reason, optimal implant length and diameter are rec-ommended to provide a large bone–implant contact surface.28High insertion torque, undersizing of the
os-teotomy, and avoidance of countersinking have been recommended to provide good initial stability.28
There is clear evidence that bone density and cortical bone thickness also are important and the use of CT images and software for three-dimensional recon-struction could provide accurate and useful informa-tion about the bone density and the cortical bone thickness before implant placement.28In the case of immediate loading, a surface capable to guarantee rapid healing time is highly recommended.
In our study, DLMF implants were used to support mandibular overdentures with an immediate loading protocol. The fabrication of dental implants with
Figure 3.
Implants at the 1-year follow-up examination.
Figure 4.
The overdenture at 1-year follow-up examination. The prosthesis has a good stability.
Figure 5.
Panoramic radiograph at the 1-year follow-up examination.
Figure 6.
Periapical radiograph of an implant at baseline (immediately after insertion).
DLMF technique presents some potential advantages that could be very helpful in immediate loading proto-cols. DLMF makes it possible to generate implants with a graded elasticity, incorporating a gradient of porosity, from the inner core to the outer surface.21-24 The outer surface of this new functionally graded material has an elastic modulus (77 [gigapascal (GPa)]) closer to that of the surrounding cortical bone (10 to 26 Gpa), for a more natural transfer of
loading stress.21,23Considering that surface contami-nation is a potential problem with the traditional pro-cess for fabricating dental implants, which is carried out under mineral oil refrigeration and with different materials for machining burs, the low risk of surface contamination is a distinct advantage of the DLMF procedure.21 Finally, DLMF technique allows the
fabrication of a porous structure with controlled po-rosity, pore interconnection, size, shape, and distribu-tion,23-26 which are requirements for rapid bone
ingrowth.23-26,29With DLMF it is possible to control
the porosity of each layer and consequently the three-dimensional model by changing the processing parameters, such as laser power and peak power (for continuous wave and pulsed lasers, respectively), laser spot diameter, layer thickness, hatching pitch (or scan spacing), scan speed and scanning strat-egy, or by modifying the size of the original titanium particles.21,23-25 Extensive body fluid transport through the porous scaffold matrix is possible, which can trigger bone ingrowth, if substantial open pore in-terconnectivity is established.29,30Pore
interconnec-tivity and pore size play a critical role in bone ingrowth regulating cell growth and function, manip-ulating tissue differentiation, and optimizing scaffold mechanical function.24,25,29 The highly porous
mi-crostructure with interconnected porous networks is critical to ensuring spatially uniform cell distribution, cell survival, proliferation, and migration in vivo.29,30
Although optimum pore size required for implant fix-ation remains undefined, the consensus is that to pro-mote bone ingrowth, pore sizes between 100 and 400 mm are necessary.31
These structural and geometric features are of para-mount importance, but are difficult to achieve with the traditional manufacturing methods used to produce dental implants.21,23Several techniques have been
in-troduced in the past few years to produce a microporous coating on the implants.32 Spraying techniques were
the most commonly used; however, the fatigue strength of an implant coated by such techniques may be re-duced by up to one-third compared to the uncoated
Figure 7.
Periapical radiograph of the implant at the 1-year follow-up control. The DLMF implant shows good osseointegration without signs of bone resorption.
Table 2.
Prosthetic Complications and Maintenance
Complication Patients (n)
Overall Incidence %
Loss of denture teeth 1 4.1
Denture fracture 1 4.1
Replacement of caps 10 41.6
implant.32Other current available methods for
produc-ing porous titanium and titanium alloy scaffolds include sintering together of the particles or plasma spray of the powder on a dense substrate followed by the cutting of the porous layer, three-dimensional fiber deposition, solid-state foaming by expansion of argon-filled pores, and polymeric sponge replication.30,32-35 However, none of these conventional techniques allows for build-ing scaffolds with a completely controlled design of the external shape and the interconnected pore net-work.21,23-26,29,30In the present study on the immediate
loading of mandibular overdentures supported by four DLMF unsplinted one-piece implants, the 1-year im-plant survival and success rate were 98.9% and 97.8%, respectively. Minimal bone loss (0.28 – 0.30 mm) was evidenced around the implants at the 1-year examination. Some prosthetic complications, such as acrylic resin fracture (4.1%) and denture teeth loss (4.1%), were reported. The number of adjustments re-quired to maintain an implant-supported overdenture (e.g., the need for reactivation or substitution of reten-tive elements and denture reline) has been shown to be substantial within the first year of service. All these adjustments were, however, related to the materials used and were considered technical in nature.
CONCLUSIONS
Based on these results, and within the limits of this study (the limited number of patients and follow-up time), the immediate loading of four unsplinted DLMF implants by means of ball attachment–supported man-dibular overdentures seems to represent a safe and successful procedure, with excellent 1-year survival (98.9%) and success rates (97.8%). No detrimental ef-fects on marginal bone level were evident after 1-year of functional loading. Some prosthetic complications were reported.
ACKNOWLEDGMENTS
The authors report no financial relationship with any commercial firm that may pose a conflict of interest for this study. No grants, equipment, or other sources of support were provided. The authors report no con-flicts of interest related to this study.
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Correspondence: Dr. Carlo Mangano, Piazza Trento 4, 22015 Gravedona (Como), Italy. Fax: 39-0344-85524; e-mail: camangan@gmail.com.
Submitted February 7, 2011; accepted for publication April 28, 2011.
