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1.
Microbiol Resour Announc ; 12(11): e0073623, 2023 Nov 16.
Article in English | MEDLINE | ID: mdl-37905830

ABSTRACT

We report the genome sequences of eight bacteriophages isolated using Gordonia rubripertincta NRRL B-16540-SEA. Based on gene content similarity to phages in the Actinobacteriophage database, six of the phages are assigned to phage cluster CT while two are assigned to cluster DJ.

2.
Small ; 19(32): e2207806, 2023 08.
Article in English | MEDLINE | ID: mdl-37060223

ABSTRACT

Ratiometric fluorescent nanothermometers with near-infrared emission play an important role in in vivo sensing since they can be used as intracellular thermal sensing probes with high spatial resolution and high sensitivity, to investigate cellular functions of interest in diagnosis and therapy, where current approaches are not effective. Herein, the temperature-dependent fluorescence of organic nanoparticles is designed, synthesized, and studied based on the dual emission, generated by monomer and excimer species, of the tris(2,4,6-trichlorophenyl)methyl radical (TTM) doping organic nanoparticles (TTMd-ONPs), made of optically neutral tris(2,4,6-trichlorophenyl)methane (TTM-αH), acting as a matrix. The excimer emission intensity of TTMd-ONPs decreases with increasing temperatures whereas the monomer emission is almost independent and can be used as an internal reference. TTMd-ONPs show a great temperature sensitivity (3.4% K-1 at 328 K) and a wide temperature response at ambient conditions with excellent reversibility and high colloidal stability. In addition, TTMd-ONPs are not cytotoxic and their ratiometric outputs are unaffected by changes in the environment. Individual TTMd-ONPs are able to sense temperature changes at the nano-microscale. In vivo thermometry experiments in Caenorhabditis elegans (C. elegans) worms show that TTMd-ONPs can locally monitor internal body temperature changes with spatio-temporal resolution and high sensitivity, offering multiple applications in the biological nanothermometry field.


Subject(s)
Nanoparticles , Thermometry , Animals , Caenorhabditis elegans , Temperature
3.
Pharmaceutics ; 15(4)2023 Mar 26.
Article in English | MEDLINE | ID: mdl-37111554

ABSTRACT

Antibiotic resistance has exponentially increased during the last years. It is necessary to develop new antimicrobial drugs to prevent and treat infectious diseases caused by multidrug- or extensively-drug resistant (MDR/XDR)-bacteria. Host Defense Peptides (HDPs) have a versatile role, acting as antimicrobial peptides and regulators of several innate immunity functions. The results shown by previous studies using synthetic HDPs are only the tip of the iceberg, since the synergistic potential of HDPs and their production as recombinant proteins are fields practically unexplored. The present study aims to move a step forward through the development of a new generation of tailored antimicrobials, using a rational design of recombinant multidomain proteins based on HDPs. This strategy is based on a two-phase process, starting with the construction of the first generation molecules using single HDPs and further selecting those HDPs with higher bactericidal efficiencies to be combined in the second generation of broad-spectrum antimicrobials. As a proof of concept, we have designed three new antimicrobials, named D5L37ßD3, D5L37D5L37 and D5LAL37ßD3. After an in-depth exploration, we found D5L37D5L37 to be the most promising one, since it was equally effective against four relevant pathogens in healthcare-associated infections, such as methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis (MRSE) and MDR Pseudomonas aeruginosa, being MRSA, MRSE and P. aeruginosa MDR strains. The low MIC values and versatile activity against planktonic and biofilm forms reinforce the use of this platform to isolate and produce unlimited HDP combinations as new antimicrobial drugs by effective means.

4.
Biomater Sci ; 10(14): 3730-3738, 2022 Jul 12.
Article in English | MEDLINE | ID: mdl-35660816

ABSTRACT

Advanced personalized immunotherapies still have to overcome several biomedical and technical limitations before they become a routine cancer treatment in spite of recent achievements. In adoptive cell therapy (ACT), the capacity to obtain adequate numbers of therapeutic T cells in the patients following ex vivo treatment should be improved. Moreover, the time and costs to produce these T cells should be reduced. In this work, inverse opal (IOPAL) 3D hydrogels consisting of poly(ethylene) glycol (PEG) covalently combined with heparin were engineered to resemble the environment of lymph nodes, where T cells get activated and proliferate. The introduction of an IOPAL strategy allowed a precise control on the porosity of the hydrogels, providing an increase in the proliferation of primary human CD4+ T cells, when compared with state-of-the-art expansion systems. Additionally, the IOPAL hydrogels also showed a superior expansion compared to hydrogels with the same composition, but without the predetermined pore structure. In summary, we have shown the beneficial effect of having an IOPAL architecture in our 3D hydrogels to help achieving large numbers of cells, while maintaining the desired selected phenotypes required for ACT.


Subject(s)
Hydrogels , Polyethylene Glycols , Cell Proliferation , Humans , Hydrogels/chemistry , Polyethylene Glycols/chemistry , Porosity , T-Lymphocytes
5.
Vive (El Alto) ; 5(13): 63-74, abr. 2022.
Article in Spanish | LILACS | ID: biblio-1410334

ABSTRACT

Los adultos mayores, por naturaleza presentan deterioro progresivo de las capacidades físico-cognitivas, donde se ven afectadas facultades como el equilibrio, la marcha, la fuerza y la movilidad funcional. El confinamiento y distanciamiento social pueden llevar a que estas personas pierdan ciertas rutinas y aumenten en ellos el riesgo de sufrir caídas y lesiones músculo esqueléticas. Objetivo. Determinar el riesgo de caídas en los adultos mayores durante el periodo de confinamiento. Materiales y métodos. Estudio de enfoque cuantitativo, alcance descriptivo, diseño no experimental y de cohorte transversal; muestra poblacional de 42 adultos mayores en la ciudad de Guayaquil, que cumplen con los criterios de inclusión, a quienes se evalúan mediante historia clínica, las pruebas Timed Up & go, Tinetti, Downton y Falls Efficacy. Resultados. Predominio del grupo poblacional de sexo femenino con edades comprendidas entre 80 y 91 años, el Test Timed Up & Go denota que el 76% presentan déficit moderado y variable de la movilidad funcional, el test de Tinetti evidencia un alto riesgo de caídas en 83% de adultos mayores, mientras que las escalas de Downton y Falls Efficacy, muestran que un 50% requiere cuidados específicos y el 48% tienen temor de caer. Conclusiones. El grupo de adultos mayores evaluados muestra una alta predisposición al riesgo de caídas, producto del déficit de la movilidad, alteración del equilibrio y marcha, como respuesta a la falta de actividad física y distanciamiento social generada durante el periodo de confinamiento de marzo a junio 2020.


Older adults, by nature, present progressive deterioration of physical cognitive capacities, where faculties such as balance, gait, strength and functional mobility are affected. Confinement and social distancing can lead to these people losing certain routines and increasing their risk of falls and musculoskeletal injuries. Objective. To determine the risk of falls in the elderly during the confinement period. Materials and methods. Study with a quantitative approach, descriptive scope, non-experimental design and a cross-sectional cohort; The population sample is of 42 older adults in the city of Guayaquil, who meet the inclusion criteria, who are evaluated through a clinical history and the tests, Timed Up & go, Tinetti, Downton and Falls Efficacy. Results. Predominance of the female population group aged between 80 and 91 years, the Timed Up & Go Test denotes that 76% present moderate and variable deficiency of functional mobility, the Tinetti test shows a high risk of falls in 83% of older adults, while the Downton and Falls Efficacy scales show that 50% require specific care and 48% are afraid of falling. Conclusions. The group of older adults evaluated shows a high predisposition to the risk of falls, product of the mobility deficit, alteration of balance and gait, in response to the lack of physical activity and social distancing generated during the confinement period from March to June 2020.


Os adultos mais velhos, por natureza, apresentam deterioração progressiva das capacidades físico-cognitivas, onde faculdades como equilíbrio, marcha, força e mobilidade funcional são afetadas. O confinamento e o distanciamento social podem levar essas pessoas a perder certas rotinas e aumentar o risco de quedas e lesões musculoesqueléticas. Objetivo. Determinar o risco de quedas em idosos durante o período de confinamento. Materiais e métodos. Estudo com abordagem quantitativa, de escopo descritivo, não experimental e com delineamento de coorte transversal; A amostra populacional é composta por 42 idosos na cidade de Guayaquil, que atendem aos critérios de inclusão, que são avaliados por meio de um histórico médico e dos testes de eficácia Timed Up & go, Tinetti, Downton e Falls. Resultados. Predominância da população feminina na faixa etária de 80 a 91 anos, o Teste Timed Up & Go denota que 76% apresentam déficit moderado e variável de mobilidade funcional, o teste de Tinetti mostra alto risco de quedas em 83% dos idosos, enquanto as escalas de Downton e Falls Efficacy mostram que 50% requerem cuidados específicos e 48% têm medo de cair. Conclusões. O grupo de adultos mais velhos avaliados apresenta elevada predisposição ao risco de quedas, produto do déficit de mobilidade, alteração do equilíbrio e marcha, em resposta à inatividade física e distanciamento social gerado durante o período de confinamento de março a junho de 2020.


Subject(s)
Humans , Aged , Aged, 80 and over , Accidental Falls , Psychological Tests , Postural Balance , Age Groups
6.
Biomaterials ; 259: 120313, 2020 11.
Article in English | MEDLINE | ID: mdl-32829146

ABSTRACT

Recent achievements in the field of immunotherapy, such as the development of engineered T cells used in adoptive cell therapy, are introducing more efficient strategies to combat cancer. Nevertheless, there are still many limitations. For example, these T cells are challenging to manufacture, manipulate, and control. Specifically, there are limitations in producing the large amounts of therapeutic T cells needed for these therapies in a short period of time and in an economically viable manner. In this study, three-dimensional (3D) poly(ethylene) glycol (PEG) hydrogels covalently combined with low molecular weight heparin are engineered to resemble the lymph nodes, where T cells reproduce. In these hydrogels, PEG provides the needed structural and mechanical properties, whereas heparin is used as an anchor for the cytokine CCL21, which is present in the lymph nodes, and can affect cell migration and proliferation. The 3D structure of the hydrogel in combination with its loading capacity result in an increased primary human CD4+ T cell proliferation compared to the state-of-the-art expansion systems consisting of artificial antigen presenting cells. Thus, we present a new tool for adoptive cell therapy to help achieving the large numbers of cells required for therapy of selected phenotypes targeted against cancer cells, by mimicking the lymph nodes.


Subject(s)
Hydrogels , Polyethylene Glycols , Cell Differentiation , Cell Proliferation , Chemokine CCL21 , Humans , T-Lymphocytes
7.
Article in English | MEDLINE | ID: mdl-31815968

ABSTRACT

Typically, healing or temporary abutments are connected and disconnected several times between implant placement and definitive restoration delivery, and soft tissue disruption occurs each time the abutment is disconnected and reconnected. This histologic event is supposed to cause bone resorption around the implant after second-stage surgery. To minimize this clinical scenario, immediately placing and never removing a definitive abutment the day of implant insertion (one-stage protocol) or at second-stage surgery in cases of submerged implants (two-stage protocol) was suggested. This paper details the prosthetic protocol and presents strategies and rationales for placing a definitive abutment the day of implant insertion or at second-stage surgery with cement- and screw-retained restorations. This protocol seems to be an efficient strategy to preserve peri-implant hard and soft tissues. However, positive outcomes in peri-implant bone and soft level changes should be viewed with caution, as their clinical significance is still uncertain.


Subject(s)
Bone Resorption , Dental Implants , Dental Abutments , Dental Implantation, Endosseous , Humans , Wound Healing
8.
J Clin Med ; 8(9)2019 Aug 24.
Article in English | MEDLINE | ID: mdl-31450607

ABSTRACT

BACKGROUND: Early peri-implant bone loss has been associated to long-term implant-prosthetic failure. Different technical, surgical, and prosthetic techniques have been introduced to enhance the clinical outcome of dental implants in terms of crestal bone preservation. The aim of the present cohort study was to observe the mean marginal bone level around two-part implants with gingivally tapered abutments one year after loading. METHODS: Mean marginal bone levels and change were computed following radiological calibration and linear measurement on standardized radiographs. RESULTS: Twenty patients who met the inclusion criterion of having at least one implant with the tapered prosthetic connection were included in the study. The cumulative implant success rate was 100%, the average bone loss was -0.18 ± 0.72 mm, with the final bone level sitting above the implant platform most of the time (+1.16 ± 0.91 mm). CONCLUSION: The results of this cohort study suggested that implants with tapered abutments perform successfully one year after loading and that they are associated with excellent marginal bone preservation, thus suggesting that implant-connection macro-geometry might have a crucial role in dictating peri-implant bone levels.

9.
RSC Adv ; 9(27): 15402-15409, 2019 May 14.
Article in English | MEDLINE | ID: mdl-35514832

ABSTRACT

Engineering new materials which are capable of trapping biomolecules in nanoscale quantities, is crucial in order to achieve earlier diagnostics in different diseases. This article demonstrates that using free radical copolymerization, polyacrylamide can be successfully functionalized with specific synthons for nanotrapping positively charged molecules, such as numerous proteins, through electrostatic interactions due to their negative charge. Specifically, two functional random copolymers, acrylamide/acrylic acid (1) and acrylamide/acrylic acid/N-(pyridin-4-yl-methyl)acrylamide (2), whose negative net charges differ in their water solutions, were synthetized and their ability to trap positively charged proteins was studied using myoglobin as a proof-of-concept example. In aqueous solutions, copolymer 1, whose net charge for a 100 chain fragment (Q pH 6/M) is -1.323 × 10-3, interacted with myoglobin forming a stable monodisperse nanosuspension. In contrast, copolymer 2, whose value of Q pH 6/M equals -0.361 × 10-3, was not able to form stable particles with myoglobin. Nevertheless, thin films of both copolymers were grown using a dewetting process, which exhibited nanoscale cavities capable of trapping different amounts of myoglobin, as demonstrated by bimodal AFM imaging. The simple procedures used to build protein traps make this engineering approach promising for the development of new materials for biomedical applications where trapping biomolecules is required.

10.
J Immigr Minor Health ; 21(1): 136-142, 2019 Feb.
Article in English | MEDLINE | ID: mdl-29511916

ABSTRACT

The purpose of this project was to design, implement, and assess a recurring interdisciplinary community health fair in an underserved border town. University of California San Diego (UCSD) medical and pharmacy students, under faculty supervision, worked alongside community partners in Calexico, California to implement a health fair two miles from the U.S.-Mexico border. Demographic and screening data were described from 293 participants from 2014 to 2016. Over 90% (269/293) listed Mexico as their country of birth, 82.9% (243/293) were monolingual Spanish speakers, 75.4% (221/293) had an annual household income of ≤ $20,000, and 58.7% (172/293) described their health as fair or poor. Screening revealed 91.1% (265/291) were overweight or obese, 37.8% (109/288) had hypertension, 9.3% (27/289) had elevated blood sugar, and 11.4% (33/289) had elevated total cholesterol levels. This model could be replicated in other training settings to increase exposure to border health issues and connect patients to local health services.


Subject(s)
Health Fairs/organization & administration , Health Status , Interdisciplinary Communication , Mass Screening/organization & administration , Mexican Americans , Adult , Aged , Blood Glucose , Blood Pressure , Body Mass Index , California/epidemiology , Cholesterol/blood , Female , Hispanic or Latino , Humans , Hypertension/diagnosis , Hypertension/ethnology , Language , Male , Mexico/ethnology , Middle Aged , Obesity/diagnosis , Obesity/ethnology , Socioeconomic Factors , Students, Medical , Students, Pharmacy
11.
Compend Contin Educ Dent ; 38(7): 482-491, 2017 Jul.
Article in English | MEDLINE | ID: mdl-28727464

ABSTRACT

Soft-tissue recession around an implant rehabilitation over time has been considered a physiologic phenomenon. The divergent profile of the abutment and the abutment's dis/reconnections are the most critical predisposing and precipitating factors regarding such gingival recession. Recent publications have discussed how tapered and marginless abutments that allow no disconnections and increase soft-tissue thickness could prevent implant rehabilitations from experiencing gingival recession. The objective of this article is to demonstrate the biologic rationale of tissue behavior surrounding tapered abutments and their clinical application.


Subject(s)
Dental Abutments , Dental Implant-Abutment Design , Gingiva/physiopathology , Gingival Recession/physiopathology , Dental Abutments/adverse effects , Dental Implants/adverse effects , Gingival Recession/rehabilitation , Hemostasis , Humans
12.
Article in English | MEDLINE | ID: mdl-27333011

ABSTRACT

The objective of this study was to clarify and evaluate the orientation of the collagen fibers around platform-switching (PS) implants with conical abutments in humans after 8 weeks of healing, and to determine how this orientation would help stabilize the soft tissue and prevent bone resorption. On PS implants, circular orientation of collagen fiber was observed as the main arrangement in a cross-sectional view. The circular collagen fibers might be the key factor in stabilizing the soft tissues around the rehabilitation, inhibiting apical migration of the soft tissues and, in turn, protecting the underlying bone.


Subject(s)
Connective Tissue/physiology , Connective Tissue/ultrastructure , Dental Implant-Abutment Design , Dental Implants, Single-Tooth , Wound Healing/physiology , Biopsy , Dental Prosthesis, Implant-Supported , Female , Gingivectomy , Humans , Male , Microscopy, Electron, Scanning , Surgical Flaps , Treatment Outcome
13.
Int J Oral Maxillofac Implants ; 29(5): 1049-52, 2014.
Article in English | MEDLINE | ID: mdl-25216128

ABSTRACT

PURPOSE: The aim of this study was to describe the average angulation and dimensions of the pterygomaxillary area in the atrophic maxilla to facilitate the orientation of pterygoid implants during their placement. MATERIALS AND METHODS: A retrospective radiologic study was made. A virtual pterygoid implant, 13, 15, or 18 mm long, was placed in the pterygomaxillary area following the axis of the bone, with a distance of at least 2 mm maintained between the artery and palatine nerve and the implant. The long axis of the implant was inclined slightly toward the palatal to follow the cortical palatal bone. The angles between the long axis of the virtual implant and Frankfort horizontal were measured in both sagittal and frontal views. To calculate the average length of the pterygomaxillary area, the virtual long axis of the implant was measured from the alveolar crest to the pterygomaxillary suture. RESULTS: The average anteroposterior axis inclination of the pterygomaxillary area was 72.5 ± 4.9 degrees relative to Frankfort horizontal. The average angulation of the palatal vestibule was 81.3 ± 42.8 degrees relative to Frankfort horizontal. The average length of the pterygomaxillary area was 22.5 ± 4.8 mm. CONCLUSION: Pterygoid implant placement requires thorough knowledge of each patient's anatomy and individual needs. The mean position of the pterygomaxillary buttress axis was 72.5 ± 4.9 degrees to the distal and 81.3 ± 2.8 degrees to the palatal relative to Frankfort horizontal. Placement of pterygoid implants in this inclination may increase accuracy of implant placement. The average length from the tuberosity to the most apical point of the pterygoid apophysis was 22.5 ± 4.8 mm. These results suggest that an implant 15 to 18 mm in length would fit in the pterygomaxillary area to reach the cortical bone.


Subject(s)
Cone-Beam Computed Tomography/methods , Maxilla/diagnostic imaging , Pterygopalatine Fossa/diagnostic imaging , Adult , Aged , Alveolar Process/diagnostic imaging , Atrophy , Cephalometry/methods , Dental Implants , Dental Prosthesis Design , Female , Humans , Male , Middle Aged , Palate/blood supply , Palate/innervation , Patient Care Planning , Retrospective Studies , Sphenoid Bone/diagnostic imaging , User-Computer Interface
14.
Article in English | MEDLINE | ID: mdl-24804289

ABSTRACT

It has been shown that implant designs and different vertical positions have an influence on crestal bone. The purpose of this study was to use finite element (FE) analysis to biomechanically investigate the influence of the stress/strain distribution in a maxillary anterior 3.0-mm-diameter implant in relation to its apicocoronal level after oblique loading. Two different FE models, depending on implant position relative to bone crest, were applied. It can be concluded that placing the implant-abutment interface supracrestally provides decreased levels of stress and strain in the surrounding bone. However, placing the implant 0.5 mm supracrestally is also acceptable according to this analysis.


Subject(s)
Dental Implants , Biomechanical Phenomena , Finite Element Analysis , Humans
15.
Clin Oral Implants Res ; 24(3): 305-11, 2013 Mar.
Article in English | MEDLINE | ID: mdl-22092773

ABSTRACT

OBJECTIVES: The purpose of this animal study was to radiologically measure the influence of abutment disconnection on bone resorption and to compare this influence on platform-switched vs. non-platform-switched implants. METHODS: The study design included extraction of all mandibular premolars in five canines . After 2 months, six implants were placed in each dog. Four of them were platform-switched (PS) implants and two were non-platform-switched (NPS) implants. Some or all of the abutments connected to the implants were disconnected at pre-ordained post-surgical intervals. Radiographs were taken at the time of implant placement and at every handling. The values for mesial (horizontal and vertical) and distal (horizontal and vertical) bone resorption were taken and compared for each implant at every abutment dis/reconnection. RESULTS: The average vertical bone resorption around NPS implants after four dis/reconnections was 1.09 mm (SD 0.25 mm), and the average horizontal bone resorption was 0.98 mm (SD 0.27 mm). The average vertical bone resorption around PS implants after four dis/reconnections was 0.24 mm, (SD 0.08 mm) and the average horizontal bone resorption was 0.24 mm (SD 0.13 mm). The difference of the average horizontal and vertical bone resorption around NPS (site D) and PS (site A) implants was statically significant (P < 0.05). The average mesial and distal bone resorption values around PS (site A) implant adjacent to a tooth were compared, and statically significant differences were found (P < 0.05). CONCLUSIONS: Implants with a PS design show less peri-implant bone resorption during the healing process and as their abutments are disconnected, than do comparably dis/reconnected NPS implants. The location of the PS implant next to a tooth may decrease radiographically visible peri-implant bone resorption significantly.


Subject(s)
Alveolar Bone Loss/diagnostic imaging , Dental Abutments , Dental Implantation, Endosseous/methods , Dental Implants , Animals , Bicuspid , Dental Prosthesis Design , Dogs , Mandible/diagnostic imaging , Mandible/surgery , Radiography , Tooth Extraction
16.
Int J Oral Maxillofac Implants ; 27(6): 1547-53, 2012.
Article in English | MEDLINE | ID: mdl-23189309

ABSTRACT

PURPOSE: To review a series of 454 pterygoid implants placed more vertically than the previous standard angle (45 degrees) over a functional loading period ranging from 2 months to 14 years with a mean follow-up period of 6 years. MATERIALS AND METHODS: A retrospective study was made. The sample was composed of patients rehabilitated with pterygoid implants between January 1997 and December 2010. Patient selection criteria included: edentulism on the posterior area of an atrophic maxilla, with less than 8 mm remaining from the sinus floor to the alveolar crest, and the presence of an anterior implant or tooth to ensure mesial support for a partial denture. After a healing period between 2 and 7 months, panoramic x-rays were taken at the time of loading. The implant length, implant diameter, implant success, and the angulation of the pterygoid implants were measured. RESULTS: Three hundred ninety-two patients (206 women and 186 men) ranging in age from 34 to 75 years were fitted with 454 pterygoid implants and followed up. The 18-mm implant length was the most favored implant to fit in the pterygoid area. Implant diameter was 3.75 mm in 448 cases (98.6%). The mean mesiodistal angulation of the pterygoid implants was 70.4 degrees±7.2. After a mean follow-up period of 6 years, 96.5% of the implants placed were successfully osseointegrated. CONCLUSIONS: The findings indicate that a mesiodistal inclination of the pterygoid implant at 70 degrees relative to the Frankfort plane following the bony column of the pterygoid region decreases the non-axial loads of the rehabilitations and exhibits good long-term survival; however, further studies are needed to assess the long-term survival of implants in the pterygomaxillary region.


Subject(s)
Dental Implantation, Endosseous/methods , Dental Implants , Maxilla , Adult , Aged , Dental Prosthesis, Implant-Supported , Dental Restoration Failure/statistics & numerical data , Female , Follow-Up Studies , Humans , Male , Maxilla/diagnostic imaging , Maxilla/pathology , Middle Aged , Osseointegration , Radiography , Retrospective Studies
17.
Int J Oral Maxillofac Implants ; 27(5): 1116-22, 2012.
Article in English | MEDLINE | ID: mdl-23057024

ABSTRACT

PURPOSE: To show the presence and direction of the collagen fiber orientation around platform-switched (PS) and non-platform switched (NPS) implants at the crestal bone level. MATERIALS AND METHODS: Twelve implants (six PS and six NPS implants) were placed with single-stage surgery in three dogs. The implant abutments were disconnected and reconnected after 8, 10, 12, and 14 weeks. The animals were sacrificed in the 18 week. The specimens were stained with hematoxylin and eosin and examined using polarized light microscopy. RESULTS: The PS implant specimens showed circular fiber orientation at the implant platform level and the NPS implants showed similar fiber orientation at the bone level of the first implant thread. All specimens demonstrated a circular fiber orientation of the collagen fibers at the crestal bone level. CONCLUSIONS: The discrepancy in implantabutment diameter involving a change from a wider implant platform to a smaller abutment diameter, described as platform switching, seems to provoke a circular fiber orientation at the implant platform level. Similar circular fiber orientation was found at the first implant thread bone level for regular implants without platform switching. The histologic results support the hypothesis that platform switching can reduce crestal bone loss and can serve as a "mechanical retention factor" for periodontal fiber orientation. More clinical and histologic studies are needed to corroborate this preliminary finding.


Subject(s)
Bone Resorption/prevention & control , Dental Abutments , Dental Implants , Fibrillar Collagens/chemistry , Alveolar Bone Loss/prevention & control , Animals , Dogs , Male , Microscopy, Polarization , Pilot Projects
19.
Int J Periodontics Restorative Dent ; 32(2): 149-55, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22292143

ABSTRACT

Because of the peri-implant bone resorption that occurs when a non-platform switched implant is exposed to the oral environment, it has been recommended to maintain 1.5 mm between the tooth and implant to preserve the bone adjacent to the teeth. Several studies have documented that platform-switched implants have less peri-implant bone resorption than matched implants. This retrospective radiographic analysis studied 70 platform-switched implants placed less than 1.5 mm from an adjacent tooth and with prostheses loaded for a minimum of 6 months. The mean distance between the implant and tooth was 0.99 mm (range, 0.20 to 1.49 mm); the mean horizontal and vertical bone resorption was 0.36 and 0.43 mm, respectively. The mean bone peak reduction was 0.37 mm. The results confirm that the use of platform-switched implants reduces bone resorption after two-piece implants have been uncovered and that it is possible to place this type of implant 1 mm from teeth while maintaining the bone level adjacent to them (the bone peak).


Subject(s)
Alveolar Bone Loss/diagnostic imaging , Dental Implant-Abutment Design , Dental Implants , Tooth/diagnostic imaging , Adult , Aged , Alveolar Bone Loss/classification , Alveolar Process/diagnostic imaging , Dental Prosthesis Design , Female , Follow-Up Studies , Humans , Male , Middle Aged , Radiography, Bitewing , Radiography, Dental, Digital , Retrospective Studies
20.
Eur J Esthet Dent ; 7(1): 36-47, 2012.
Article in English | MEDLINE | ID: mdl-22319763

ABSTRACT

It is currently accepted that success in implant-supported restorations is based not only on osseointegration, but also on achieving the esthetic outcome of natural teeth and healthy soft tissues. The socalled "pink esthetic" has become the main challenge with implant-supported rehabilitations in the anterior area. This is especially difficult in the cases with two adjacent implants. Two components affect the final periimplant gingiva: a correct bone support, and a sufficient quantity and quality of soft tissues. Several papers have emphasized the need to regenerate and preserve the bone after extractions, or after the exposure of the implants to the oral environment. The classical implantation protocol entails entering the working area several times and always involves the surgical manipulation of peri-implant tissues. Careful surgical handling of the soft tissues when exposing the implants and placing the healing abutments (second surgery) helps the clinician to obtain the best possible results, but even so there is a loss of volume of the tissues as they become weaker and more rigid after each procedure. The present study proposes a new protocol that includes the connective tissue graft placement and the soft tissues remodeling technique, which is based on the use of the ovoid pontics. This technique may help to minimize the logical scar reaction after the second surgery and to improve the final emergence profile.


Subject(s)
Dental Implantation, Endosseous , Esthetics, Dental , Gingiva/pathology , Alveolar Process/pathology , Bone Regeneration/physiology , Cicatrix/prevention & control , Connective Tissue/transplantation , Crowns , Dental Implant-Abutment Design , Dental Implantation, Endosseous/methods , Dental Prosthesis, Implant-Supported , Denture Design , Denture, Partial, Removable , Denture, Partial, Temporary , Gingiva/transplantation , Humans
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