Carga inmediata de implantes extra cortos en sectores posteriores. Estudios retrospective con tres modelos de carga: 24, 48 hs y 7 días / Immediate loading of extra short implants in posterior sectors. Retrospective study with three loading models: 24 hs, 48 hs and 7 days

Los implantes extra-cortos son cada vez más utili-zados en la práctica clínica diaria. La utilización de estos implantes con carga inmediata supone un reto añadido. Clásicamente se ha postulado que la carga inmediata debe realizarse después de 24 horas de la cirugía. En la siguiente serie de casos analizamos diferentes tiempos a la hora de realizar la carga in-mediata y su posible repercusión. Fueron recolec-tados de forma retrospectiva datos sobre casos de implantes extra-cortos (5,5 y 6,5 mm) en los que fue realizada una carga inmediata en sectores poste-riores. El implante fue la unidad de análisis para la estadística descriptiva en cuanto a la localización, dimensiones del implante, y mediciones radiográ-ficas. El paciente fue la unidad de medida para el análisis de la edad, sexo y la historia clínica. La prin-cipal variable estudiada fue la supervivencia de los implantes extra-cortos con carga inmediata en tres períodos de tiempo determinados: 24 hs, 48 hs y 7 días y como variables secundarias se han estudiado, la estabilidad del hueso crestal en general y en los tres períodos de carga anteriormente mencionados, las complicaciones protésicas y la supervivencia de las prótesis. Fueron reclutados 74 pacientes en los que se insertaron 146 implantes que cumplieron con los criterios de inclusión. Todos los implantes fueron cargados mediante carga inmediata en tres perío-dos determinados de tiempo: 24 hs (40 implantes), 48 hs (42 implantes) y 7 días (42 implantes). Todos los implantes fueron ferulizados a otros implantes ge-nerándose puentes de dos o más unidades, con di-ferente longitud. En el grupo de implantes con carga inmediata en 24 hs la media de la pérdida ósea distal de todos los implantes fue de 0,21 mm (+/-0,84) y la media de la pérdida ósea mesial en este grupo fue de 0,33 mm (+/- 0,53). En el grupo de carga inmediata en 48 hs, la media de la pérdida ósea distal de todos los implantes fue de 0,20 mm (+/- 0,82) y la media de la pérdida ósea mesial fue de 0,22 mm (+/- 0,81). En el grupo de carga de 7 días, la pérdida ósea me-sial del grupo fue de 0,28 mm (+/- 0,51) y la media de la pérdida ósea distal fue de 0,17 mm (+/- 0,81). Cuando comparamos las medias de pérdida ósea me-sial y distal entre los tres grupos, no se observaron diferencias estadísticamente significativas (mesial p=0,062, distal p=0,067). En conclusión, no se obser-varon diferencias significativas en la pérdida ósea crestal ni en la supervivencia de los implantes cortos entre los 3 tiempos estudiados de aplicación de car-ga inmediata. Por ello, utilizar cualquiera de los tres protocolos puede ser adecuado, mientras se realice un correcto análisis de la situación clínica de cada paciente (AU)

Extra-short implants are increasingly used in daily clinical practice. The use of these implants with immediate loading poses an added challenge. Classically it has been postulated that immediate loading should be performed 24 hrs after surgery. In the following case series, we analyze different times of immediate loading and their possible repercussions. We retrospectively collected data on cases of extra-short implants (5.5 and 6.5 mm) in which immediate loading was performed in posterior sectors. The implant was the unit of analysis for descriptive statistics in terms of location, implant dimensions, and radiographic measurements. The patient was the unit of measurement for the analysis of age, sex and medical history. The main variable studied was the survival of immediately loaded extra-short implants in three specific time periods: 24 hrs, 48 hrs and 7 days. Secondary variables studied were crestal bone stability in general and in the three loading periods mentioned above, prosthetic complications and prosthesis survival. Seventy-four patients were recruited and 146 implants that met the inclusion criteria were inserted. All implants were loaded by immediate loading in three specific time periods: 24 hrs (40 implants), 48 hrs (42 implants) and 7 days (42 implants). All implants were splinted to other implants generating bridges of two or more units, with different lengths. In the 24-hr immediate loading group the mean distal bone loss of all implants was 0.21 mm (+/- 0.84) and the mean mesial bone loss in this group was 0.33 mm (+/- 0.53). In the 48-hr immediate loading group, the mean distal bone loss for all implants was 0.20 mm (+/- 0.82) and the mean mesial bone loss was 0,22 mm (+/- 0,81). In the 7-day loading group, the mesial bone loss of the group was 0.28 mm (+/- 0.51) and the mean distal bone loss was 0.17 mm (+/- 0.81). When we compared the mean mesial and distal bone loss between the three groups there were no statistically significant differences (mesial p=0.062, distal p=0.067). In conclusion, no significant differences were observed in crestal bone loss or in the survival of short implants between the 3 immediate load application times studied. Therefore, using any of the three protocols can be appropriate, as long as a correct analysis of the clinical situation of each patient is performed (AU)

Peri-implant clinicoradiographic status among betel-quid chewers and controls

Abstract The aim of the present case-control observational study was to evaluate the peri-implant clinicoradiographic status among betel-quid chewers and controls. Self-reported betel-quid chewers and controls were included. Participants were categorized into 3 groups: Group-1: Individuals chewing betel-quid with tobacco; Group-2: Individuals chewing betel-quid without tobacco; and Group-3: Controls (individuals not using tobacco in any form). Demographic data was collected using a questionnaire. Periodontal and peri-implant clinicoradiologic parameters (plaque and gingival indices [PI and GI], probing depth [PD] and crestal bone loss/marginal bone loss [CBL/MBL]) were assessed. Clinical attachment loss (AL) around teeth was also assessed. Group comparisons were done using the one-way analysis of variance and Bonferroni Post-hoc adjustment tests. Correlation of periodontal and peri-implant inflammatory parameters with the duration of betel-quid chewing habit and duration of placement in the mouth were assessed using logistic regression analysis. P<0.05 was considered statistically significant. Thirty, 30 and 30 patients were included in groups 1, 2 and 3, respectively. Full-mouth PI (P<0.01), GI (P<0.01), clinical AL (P<0.01), PD (P<0.01) and mesial and distal MBL (P<0.01) were higher in groups 1 and 2 than Group-3. Peri-implant mPI (P<0.01), mGI (P<0.01), PD (P<0.01) and MBL/CBL (P<0.01) were significantly higher in groups 1 and 2 than Group-3 with no significant difference in groups 1 and 2. Betel-quid chewing habit either with or without tobacco is a risk-factor of peri-implant soft-tissue inflammation and CBL.

Resumo O objetivo do presente estudo observacional de casos-controles foi avaliar o estado clínico-radiográfico periimplantar dos usuários de bétele. Foram incluídos usuários que relataram utlizar a substância bétele como tabaco de mascar. Os participantes foram categorizados em 3 grupos: Grupo-1: Indivíduos que mascam bétele com tabaco; Grupo-2: Indivíduos que mascam bétele sem tabaco; e Grupo-3: Controle (indivíduos que não usam tabaco sob qualquer forma). Os dados demográficos foram recolhidos utilizando um questionário. Foram avaliados parâmetros clínico-radiográfico e periimplantares (índices placa e gengivais [IP e IG], profundidade de sondagem [PS] e perda de crista óssea/ perda óssea marginal [PCO/POM]). Também foi avaliada a perda inserção clínica (IC) em torno dos dentes. As comparações de grupo foram feitas utilizando a análise de variância unidireccional e os testes de ajustamento post-hoc de Bonferroni. A correlação dos parâmetros inflamatórios periodontais e periimplantares com a duração do hábito de mastigação da bétele e duração da colocação na boca foi avaliada utilizando a análise de regressão logística. P<0,05 foi considerado estatisticamente significativo. Foram utilizados 30 pacientes em cada grupo. O IP de boca inteira (P<0,01), IG (P<0,01), IC clínica (P<0,01), PS (P<0,01) e POM mesial e distal (P<0,01) foram mais elevados nos grupos 1 e 2 do que no grupo 3. O mPI peri-implantar (P<0,01), '(P<0,01), PD (P<0,01) e POM/PCO (P<0,01) foram significativamente mais elevados nos grupos 1 e 2 do que no grupo 3, sem diferença significativa nos grupos 1 e 2. O hábito de mastigar a substância bétele com ou sem tabaco é um fator de risco de inflamação dos tecidos moles periimplantares e PCO.

Relationship between Gingival Biotype and Underlying Crestal Bone Morphology

PURPOSE: The purpose of this study was to assess the relationship between gingival biotype and underlying crestal bone morphology in the maxillary anterior region. MATERIALS AND METHODS: The maxillary anterior teeth from 40 subjects (20 thin biotype, 20 thick biotype) with ages from 20 to 50 years were included in this study. All subjects had healthy gingiva in the maxillary anterior region and had no history of orthodontic treatment, periodontal treatment, or hyperplastic medication. Using the probe transparency method, the scalloped distance (SCD) between the contact point-bone crest and the midface-bone crest was measured for each maxillary anterior teeth of two groups. RESULT: The mean SCD was 3.00±0.21 mm in thin biotype and 2.81±0.20 mm in thick biotype. The SCD value in the thin biotype was statistically significantly greater than in the thick biotype (t=2.982, P<0.01). Comparing the degree of crestal bone scallop in each maxillary anterior teeth in the two groups, all six teeth in the thin biotype showed higher bone scallop than in the thick biotype. CONCLUSION: A simple procedure using a probe could to determine gingival biotype and to predict the underlying crestal bone morphology was introduced. This may be useful for effective treatment planning.

Flapless versus open flap techniques of implant placement: A 15‑month follow‑up study.

Aim: To evaluate and compare the effect of flapless and “open flap” techniques of implant placement on crestal bone height (CBH) around implants. Materials and Methods: This prospective study comprised of 32 implants placed in 16 subjects with a bilateral missing mandibular first molar. In each subject, one implant was placed with “flapless” and other using “open flap” technique. Radiographic assessment of CBH was carried out using standardized intraoral periapical radiograph of the site at baseline, 3 months, 9 months and 15 months after implant placement. Statistical Analysis: Data were analyzed using STATA 11.0 statistical software. To determine the changes in CBH from baseline, at 3‑, 9‑, and 15‑month, repeated measures analysis of variance followed by post‑hoc Bonferroni was used for each of the two techniques for mesial and distal aspects separately. For both techniques, changes in CBH from baseline to 15 months were compared using an independent t‑test with a confidence interval of 95%. Results: For “flapless” technique, there was no statistically significant (P > 0.05) reduction of CBH in initial 9 months but was significant for the 9–15 months period while for “open flap” technique, statistically significant (P < 0.05) reduction was observed up to 15 months. Comparison of both techniques showed significantly lesser reduction with “flapless” than “open flap” technique. The overall average crestal bone loss was 0.046 ± 0.008 mm on mesial aspect, 0.043 ± 0.012 mm on distal aspect with “flapless” technique and 1.48 ± 0.085 mm on mesial aspect, 1.42 ± 0.077 on distal aspect “open flap” technique. Conclusions: Both techniques showed a reduction in CBH with time but the flapless technique showed a lesser reduction. Therefore, the flapless technique can be considered as a better treatment approach for placement of implants, especially where adequate width and height of available bone are present.

Implante post exodoncia y provisionalización inmediata: reporte de un caso clínico / Postextraction implant and immediate provisionalization: report of a clinical case

La colocación de implantes dentales es una alternativa de tratamiento que ofrece La colocación de implantes dentales son una alternativa de tratamiento que ofrece buenos resultados para dientes que por distinta causa están indicados a la exodoncia. Los implantes dentales inmediatos a la extracción dental surgen a la exigencia de acortar los tiempos de tratamiento y, sobre todo, a la necesidad de preservar las estructuras alveolares que sin ellas estarían destinadas a atrofiarse. Presentamos un caso tratado con la colocación de un implante post extracción y el manejo de tejidos periimplantarios con provisionalización inmediata.

Dental Implant placement is a treatment option that provides good results for teeth thatby any chance have been planned to be extracted Immediate implants arise for the requi-rement to shorten overall treatment time but also to preserve alveolar structures whichwill atrophy without them. We present a case report about an immediate dental implantand immediate provisionalization to manage peri-implant tissues.

Maxillary crestal bone loss around bredent sky blue implants: one year study

Objective: To analyze the amount of crestal bone loss of the mandible around implants of different diameters one year after implantation. Material and Methods: The study included a total of 42 male and female patients. A total of 73 implants were evaluated (12 implants of diameter 3.5 x 10 mm and 61 implants of diameter 4.0 x 8 mm). Dental panoramic radiographs were made before surgery, immediately after surgery and one year later. The measurements were performed using Kodak dental software 6.11.7.0 after implantation and one year later. The data were analyzed using the IBM SPSS v.17 software package (descriptive statistics, paired samples t-test). Results: Among male patients, 43.5% were smokers, while among females, 57.9% were nonsmokers. Crestal bone resorption was greater mesially than distally, although differences were not statistically significant (p<0.05). Conclusion: All implants showed successful tissue integration. Crestal bone resorption was greater mesially than distally, although differences were not statistically significant...

“Platform switching”: Serendipity.

Implant dentistry is the latest developing field in terms of clinical techniques, research, material science and oral rehabilitation. Extensive work is being done to improve the designing of implants in order to achieve better esthetics and function. The main drawback with respect to implant restoration is achieving good osseointegration along with satisfactory stress distribution, which in turn will improve the prognosis of implant prosthesis by reducing the crestal bone loss. Many concepts have been developed with reference to surface coating of implants, surgical techniques for implant placement, immediate and delayed loading, platform switching concept, etc. This article has made an attempt to review the concept of platform switching was in fact revealed accidentally due to the nonavailability of the abutment appropriate to the size of the implant placed. A few aspect of platform switching, an upcoming idea to reduce crestal bone loss have been covered. The various methods used for locating and preparing the data were done through textbooks, Google search and related articles.

Plataforma reduzida, uma solução estética. Revisão de Literatura / Platform switching: an aesthetic solution. Literature review

O objetivo da presente revisão da literatura foi avaliar a influência do uso de plataformas reduzidas sobre os níveis de crista óssea considerando-se o tipo de conexão, carga mastigatória e necessidades estéticas. De acordo com a literatura pesquisada, concluiu-se que a plataforma reduzida mantém a crista óssea em níveis satisfatórios em torno de implante tanto hexágono externo, interno e cone Morse, implantes com carga imediata com plataforma reduzida em regiões que não sofrem cargas excessivas mantêm a crista óssea em níveis satisfatórios. A utilização de plataforma reduzida em áreas estéticas é uma opção para manter o nível da crista óssea, garantindo a manutenção das papilas e melhorando os contornos dos tecidos peri-implantares.

The purpose of this literature review was to evaluate the influence of using platforms switching considering the levels of bone crest, type of connection, masticatory load and aesthetic needs. According to the literature, it was concluded that the platform switching keeps the bone crest at satisfactory levels around the implant both external hexagon, internal hexagon and Morse taper, with immediate loading implants with platform switching in regions that do not suffer from excessive loads maintains the crest bone at satisfactory levels. The use of the platform switching in aesthetic areas is an option to keep the bone crest level, ensuring the maintenance of the papillae and improving tissue contours periimplant.

Implant crest module: A review of biomechanical considerations.

The success of dental implants has long been established through various studies with a particular emphasis laid on an implant design. Crest module is that portion of a two-piece metal dental implant, designed to hold the prosthetic components in place and to create a transition zone to the load bearing implant body. Its design, position in relation to the alveolar crest, and an abutment implant interface makes us believe that, it has a major role in integration to both hard and soft tissues. Unfortunately, in most clinical conditions, early tissue breakdown leading to soft tissue and hard tissue loss begins at this region. Early crestal bone loss is usually highest during the first year after placement ranging from 0.9 to 1.6mm and averaged 0.05-0.13mm in the subsequent years . Various hypotheses have been stated to reason it however, none has been proved convincingly. In light of this, various attempts have been made to overcome this undesirable bone loss, by varying an implant design, the position, surgical protocol, and the prosthetic options. Irrespective of an implant system and designs that are used, crestal bone loss of up to the first thread is often observed. The purpose of this review is to look into the various designs and treatment modalities, which have been introduced into the crest module of an implant body to achieve the best biomechanical and esthetic result.

Crestal bone preservation: A review of different approaches for successful implant therapy.

The level of bone crest surrounding the implant is of utmost significance to determine osseointegrated implant success, as preservation of marginal bone height is highly important for long-term dental implant survival. Various approaches have been described in the literature to prevent the crestal bone loss, including platform switching, non-submerged approach, scalloped implants, implant design modifications, progressive loading, immediate implant placement, etc. The purpose of this paper is to review all the possible methods to preserve the crestal bone, when each method should be used and their success rates in an attempt to address this complex problem of crestal bone resorption. "PubMed" and "Google Scholar" were used to find out any studies involving platform switching concept from 1990 up to 2009. Twenty-four studies involving methods for preservation of crestal bone were evaluated, which included 26% studies on platform switching, 22% on non-submerged approach, 17% on scalloped implants, 13% on progressive loading and 22% on immediate implant placement. Crestal bone preservation should be thought of starting from the design of the implant to be placed. The technique to be followed in a given case will depend upon the density of bone, force factors by the patient, bone volume and amount of soft tissues, etc. The best possible method or the combination of the methods should be used to preserve the crestal bone for the long-term success of the implants.

Projection of the oblique line in periapical radiographs of mandibular molars / Projeção da linha oblíqua na região de molares inferiores em radiografias periapicais

Purpose: To identify and quantify the frequency of the projection of the oblique line over the alveolar crests of the mandibular molars in periapical radiographs. Methods: Five hundred periapical radiographs of the mandibular molar region were selected and evaluated for the presence or absence of the oblique line. When present, its interference on the image of the alveolar crest of the mandibular molars was analyzed. The data obtained was expressed as a percentage of the overlap of the oblique line to the alveolar crests of the mandibular molars. Results: The oblique line was observed in 363 out of the 500 periapical radiographs (72.6%). Out of the 363, 308 (84.8%) showed an overlap of the oblique line over the alveolar crests. However, 55 radiographs (15.1%) did not show such interference. Of the radiographs showing an overlap (308), the incidence of an overlap was 64.6% at a single site (199 radiographs), 33.4% at two sites (103 radiographs), and 1.9% (6 radiographs) at three sites. Conclusion: The overlap of the oblique line over the image of the alveolar crests in the mandibular molar region was observed in a significant portion of the total sample.

Objetivo: Identificar e quantificar a frequência da projeção da linha oblíqua sobre as cristas alveolares dos molares inferiores em radiografias periapicais. Metodologia: Foram selecionadas 500 radiografias periapicais da região de molares inferiores e avaliada a presença ou a ausência da linha oblíqua. Quando presente, foi analisada a interferência desta estrutura sobre a imagem das cristas alveolares dos molares inferiores. Os dados obtidos, considerando a frequência da sobreposição da linha oblíqua sobre as cristas alveolares dos molares inferiores foram expressos em percentagens. Resultados: Nas 500 radiografias periapicais avaliadas, a linha oblíqua foi observada em 363 radiografias (72,6%). Nestas, em 308 (84,8%), houve sobreposição da linha oblíqua sobre as cristas alveolares. Entretanto, em 55 radiografias (15,1%) não foi encontrada interferência. Nas radiografias em que houve a sobreposição da linha oblíqua sobre as cristas alveolares (308), a incidência de sobreposição em apenas um local foi de 64,6% (199 radiografias); em dois locais foi de 33,4% (103 radiografias) e em três locais foi de 1,9% (6 radiografias). Conclusão: A sobreposição da linha oblíqua sobre a imagem das cristas alveolares na região de molares inferiores representou uma fração significativa do total da amostra.

Platform switching: uma realidade na preservação da crista óssea ao redor de implantes: revisão de literatura / Platform switching: a reality on crestal bone preservation around dental implants: literature review

A Implantologia atual admite como padrão de normalidade a perda de tecido ósseo marginal ao nível da primeira rosca de implantes osseointegráveis (Brãnemark System®). Em áreas estéticas e/ou de pequena disponibilidade óssea, esse fenômeno traz prejuízos no posicionamento cervical do tecido mole, na conformação da papila interproximal e na diminuição da superfície do implante para osseointegração. O conceito de Platform Switching, utilização de plataformas expandidas e componentes protéticos de menor diâmetro que medialisam a junção implante-abutment, minimiza ou elimina essa perda óssea. O objetivo desse artigo é expor essa ferramenta para preservação da crista óssea ao redor de implantes osseointegráveis.

The current implant dentistry considers the loss of marginal bone tissue at the level of the first thread of osseointegrated implants ("ad modum" Branemark) as normal. In aesthetic areas and/or areas of small bone availability, such phenomenon impedes the cervical positioning of the soft tissue, the interproximal papilla contour, and reduces the surface of the implants for osseointegration. The concept of Platform Switching uses expanded platforms and narrower diameter prosthetic components that medialize the implant-abutment junction (IAJ). Thus, minimizing or eliminating bone loss. The purpose of this article is to expose this tool for preservation of the crestal bone of osseointegrated implants in a literature review.

Finite element analysis of peri-implant bone stress influenced by cervical module configuration of endosseous implant / 대한치과보철학회지

STATEMENT OF PROBLEM: Crestal bone loss, a common problem associated with dental implant, has been attributed to excessive bone stresses. Design of implant's transgingival (TG) part may affect the crestal bone stresses. PURPOSE: To investigate if concavely designed geometry at a dental implant's TG part reduces peri-implant bone stresses. MATERIAL AND METHODS: A total of five differently configured TG parts were compared. Base model was the ITI one piece implant (Straumann, Waldenburg, Switzerland) characterized by straight TG part. Other 4 experimental models, i.e. Model-1 to Model-4, were designed to have concave TG part. Finite element analyses were carried out using an axisymmetric assumption. A vertical load of 50 N or an oblique load of 50 N acting at 30degrees with the implant's long axis was applied. For a systematic stress comparison, a total of 19 reference points were defined on nodal points around the implant. The peak crestal bone stress acting at the intersection of implant and crestal bone was estimated using regression analysis from the stress results obtained at 5 reference points defined along the mid plane of the crestal bone. RESULTS: Base Model with straight configuration at the transgingival part created highest stresses on the crestal bone. Stress level was reduced when concavity was imposed. The greater the concavity and the closer the concavity to the crestal bone level, the less the crestal stresses. CONCLUSION: The transgingival part of dental implant affect the crestal bone stress. And that concavely designed one may be used to reduce bone stress.

Platform switching: avaliação biomecânica por meio do método de elementos finitos tridimensional / Platform switching: biomechanical evaluation using three-dimensional finite element analysis

Introdução e Justificativa. No tratamento com implantes osseointegrados, o tecido ósseo peri-implantar sofre um processo de aposição e reabsorção, durante o primeiro ano após a restauração protética. Tem sido relatado que a platform switching reduz a remodelação óssea esperada, muito embora os mecanismos responsáveis por este processo não estejam claramente elucidados. Objetivo. O objetivo deste trabalho foi avaliar a distribuição de tensões no tecido ósseo peri-implantar, nos implantes e componente protéticos de coroa metalocerâmica implantossuportada, utilizando o conceito de platform switching e comparando-o com uma conexão regular abutment-implante, por meio do método de elementos finitos tridimensional (MEF-3D). Material e métodos. Dois modelos 3D reproduziram uma conexão regular entre abutment-implante com componentes de mesmo diâmetro (grupo Plataforma Regular - PR) e uma conexão com o conceito de platform switching (grupo Platform Switching - PS). Um implante regular (plataforma protética de 4.1mm) e um implante largo (plataforma protética de 5.0mm) foram utilizados para representar PR e PS, respectivamente, nos quais um componente protético regular de 4.1mm foi conectado para simular a coroa protética. Uma carga de 100N foi aplicada utilizando-se o programa ANSYS. Resultados. PS diminuiu a concentração de tensões no implante quando comparado com PR, alterando a distribuição das tensões na plataforma protética, o que resultou em diminuição das tensões no parafuso e tecido ósseo e aumento das tensões na coroa. Conclusões. Platform switching reduziu as tensões no tecido ósseo peri-implantar, o que pode resultar em uma diminuição da reabsorção óssea marginal. A utilização de componentes protéticos de menor diâmetro que a plataforma protética do implante diminuiu a concentração das tensões nos implantes e no parafuso, podendo resultar em uma diminuição das complicações nas próteses implantossuportadas parafusadas.

Statement of problem. After implant insertion and loading, crestal bone usually undergoes remodeling and resorption during the first year following prosthetic restoration. It has been reported that the platform switching seems to reduce or eliminate the expected postrestoration crestal bone remodeling, although the mechanisms responsible for this process are not yet clearly drawn. Purpose. The objective of this study was to evaluate the stress distribution in periimplant bone tissue, implants and prosthetic components of single crown implantssupported with the use of platform switching concept, using three-dimensional Finite Element Analysis (3D- FEA). Material and methods. Two 3D finite element models reproduced a external hexagonal implant system with peri-implant bone tissue, in which a regular matching diameter connection of abutment-implant (Regular Platform group - RPG) and a platform switching connection (Platform Switching group - PSG) were simulated. A regular implant (prosthetic platform of 4.1mm) and a wide implant (prosthetic platform of 5.0mm) were used to represent the RPG and PSG, respectively, in which a regular prosthetic component of 4.1mm was connected to represent the crown. A load of 100N was applied on the models using ANSYS software. Results. PSG diminished the stress concentration at the implant when compared to RPG by altering the stress distribution at the prosthetic platform of the implant, which results in a decrease of stress into the screw and supporting bone and an increase of stress in the crown. Conclusions. Platform switching improved biomechanically the stress distribution in peri-implant bone tissue of implant system, which might result in a reduced marginal bone loss. The use of mismatching prosthetic components in relation to the implant prosthetic platform diameter seems to decrease stress concentration at implant and screw, which might represent less clinical complications.

Influence of interimplant distance on bone resorption : A radiological and histological study in beagle dogs

INTRODUCTION: Possible etiologic factors associated with bone loss around implants after implantation are surgical trauma, occlusal overload, peri-implantitis, presence of micro gap and the formation of biologic distances. Tarnow et al. observed that the crestal bone loss was greater when the distance between the implants was or =3mm apart. The aim of this study was to evaluate the influence of different interimplant distance on marginal bone and crestal bone resorption in the beagle dogs. MATERIALS AND METHODS: The mandibular premolars of 5 dogs were extracted bilaterally. After 12 weeks of healing, each dog received 7 implants. On each side, implants were separated by 2mm (Group 1) and by 5mm (Group 2). After 16 weeks of healing, the dogs were sacrificed. Marginal bone loss was determined through linear measurements made between the implant-abutment junctions and the most coronal portions of the bone in contact with the implant surface. A line was drawn uniting the implant-abutment junctions of the adjacent implants, and a linear measurement was made at the midpoint in the direction of the most coronal peak of the interimplant bone crest to determine the crestal bone loss. Both of them was measured radiologically and histologically. RESULT AND CONCLUSION: In radiological analysis, the mean of marginal bone loss was 1.26+/-0.14mm for group 1 and 1.23+/-0.34mm for group 2, the mean of crestal bone loss was 1.10+/-0.14mm for group 1 and 1.02+/-0.30mm for group 2. The results were not statistically significant between 2 groups. In histological analysis, the mean of marginal bone loss was 1.63+/-0.48mm for group 1 and 1.62+/-0.50mm for group 2, the mean of crestal bone loss was 1.23+/-0.35mm for group 1 and 1.15+/-0.39mm for group 2. The differences were also not statistically significant. The clinical significance of this result is that the increase in the crestal bone loss results in the increase in the distance between the base of the interproximal contact of the crowns and the bone crest, and this determines if papilla will be present or absent between implants. Considering this fact, keeping up sufficient interimplant distance is important to minimize crestal bone loss.

The study on the survival rates and crestal bone changes around the implants / 대한치주과학회지

The success and failure of dental implants depends on various factors such as patient's systemic status, quantity and quality of surrounding bone, presence or absence of marginal infection and mechanical loading condition. The measurement of crestal bone changes around the implants is implemental to evaluate the success and long-term prognosis of the implant. This study was to evaluate the cumulative survival rate of the implants which had been placed in the Department of Periodontics, Chonnam National University Hospital between 1992 and 2003, and to observe the crestal bone loss around the implants which had at least 2 consecutive periapical radiographs after connecting the transmucosal abutment. The radiographs were scanned and digitalized, and the crestal bone levels on the mesial and distal surface of implants were measured using Image analyzer (Image Pro Plus, Media Cybernetics, USA), immediately after implant placement, at 2nd surgery, and 3 months, 6 months, 1 year, and every year thereafter. Any bone loss was not observed during the period between the 1st and 2nd surgery, and the bone loss was 0.86 +/- 0.92 mm for the first year of loading after connecting the transmucosal abutment. After 1 year of loading, annual bone loss was 0.1 +/- 0.27 mm, and total bone loss was 0.90 +/- 0.80 mm (during the average follow-up periods of 22.5 +/- 25.6 Mos). The implant, with smooth surface, in the mandible, and with the fixed bridge prosthesis showed greater bone loss, compared to those, with the rough surface, in the maxilla and with single crown. In systemically diseased patients (including DM or osteoporosis), the greater bone loss was observed. The cumulative survival rate among 432 implants was 94.10% for 7 years. Among 15 failed implants, 9 implants were removed due to mobility from disintegration of bone-implant interface. From this results, crestal bone loss around the implants were greatest during 1 year after transmucosal abutment connection, and various factors could affect peri-implant bone loss. To prevent and predict the bone loss around the implants and improve the prognosis, further comprehensive maintenance and follow-up schedules are required.

Radiographic evaluation of the proximal bone level between two implants: A 3-year comparative study between Branemark and ITI implants in the mandibular posterior region / 대한치과보철학회지

STATEMENT OF PROBLEM: Branemark or ITI are two currently most widely used implant systems but with contrasting design, surgical and restoration methods. PURPOSE: The purpose of this study was to compare changes and its statistical significance in bone height and shape which may rise due to the differences between two implant systems. Also to analyse the effect of inter-implant distance on annual bone height changes. MATERIAL & METHOD: Those patients who were treated with two or more of either Branemark or ITI implants at posterior mandibular area at Yonsei University Dental Hospital, Implant Clinic were selected. At annual examination appointments, standardised radiographs using parallel technique were taken. Marginal bone and inter-implant crestal bone changes were measured and following results were obtained. RESULTS: 1) When ITI and Branemark system were compared, both annual marginal and inter-implant crestal bone height changes in ITI system in the first two years were smaller than Branemark and they were statistically significant. On the third year, however, there was no statistical difference between two implant systems on their annual bone level changes (p>0.05). 2) The Marginal and inter-implant crestal bone changes were compared when inter-implant distance was less than 4mm. Statistically significant bone level changes were noted on the first year only for ITI implants but in the first and second year for Branemark implants (p>0.05). 3) When comparing angulation changes between marginal bone and implant fixture, ITI system had smaller angulation changes but the annual changes were not statistically significant (p>0.05). CONCLUSION: Within the limitation of this study, it could be concluded that Branemark implant systems had more changes in marginal and inter-implant crestal bone level in the first and second year after loading with statistical significance. Further studies are recommended to see the effects of these bone loss during the first and second year after loading on the long term prognosis of Branemark Implants.