universidade federal fluminense faculdade de …§ão flávio... · para avaliar a presença de...
TRANSCRIPT
UNIVERSIDADE FEDERAL FLUMINENSE
FACULDADE DE ODONTOLOGIA
UMA COMPARAÇÃO VOLUMÉTRICA DOS MODELOS DE GESSO OBTIDOSCOM SILICONE DE ADIÇÃO E SILICONE CONDENSAÇÃO, CRISTALIZADOS
COM E SEM PRESSURIZAÇÃO.
Niterói
2018
CAPACAPA
2
UNIVERSIDADE FEDERAL FLUMINENSE
FACULDADE DE ODONTOLOGIA
UMA COMPARAÇÃO VOLUMÉTRICA DOS MODELOS DE GESSO OBTIDOSCOM SILICONE DE ADIÇÃO E SILICONE CONDENSAÇÃO, CRISTALIZADOS
COM E SEM PRESSURIZAÇÃO.
FLÁVIO FERRAZ FILHO
Dissertação apresentada à Faculdade de Odontologia daUniversidade Federal Fluminense, como parte dosrequisitos para obtenção do título de Mestre, peloPrograma de Pós-Graduação em Odontologia.
Área de Concentração: Clínica Odontológica Orientador: Prof. Dr. Edgard de Mello Fonseca
Co-Orientador: Prof. Dr. Waldimir Rocha de Carvalho
Niterói
2018
3
BANCA EXAMINADORA
Prof. Dr. Edgard de Mello Fonseca
Instituição: Faculdade de Odontologia da UFF
Decisão: Assinatura:
Profa. Dra. Eliane dos Santos Porto Barboza
Instituição: Faculdade de Odontologia da UFF
Decisão: Assinatura:
Profa. Dra. Mônica Zacharias Jorge
Instituição: Universidade Federal do Rio de Janeiro (UFRJ)
Decisão: Assinatura:
Prof. Dr. Waldimir Rocha de Carvalho
Instituição: Faculdade de Odontologia da UFF
4
DEDICATÓRIA
A Deus, de onde vem todas as coisas.
Aos meus pais Fla ́vio Ferraz e Wilda Ferraz.
Para minha filha Fla ́via Trigueiros Ferraz.
5
AGRADECIMENTOS
Ao Professor Dr. Waldimir Rocha de Carvalho. Por ser um exemplo de
ética, disposição, excelência no ensino e amizade.
Ao Dr. Vinícius Farias Ferreira. Pelo seu brilhantismo, apoio e amizada.
A toda equipe de funcionários do Laboratório de Biotecnologia Aplicada
(LABA) por todo apoio dado.
Ao TPD Flávio Mussalém. Obrigado por ter cedido seu espaço, no
laboratório, para realização de parte da pesquisa.
6
RESUMO
(Ferraz FF). UMA COMPARAÇÃO VOLUMÉTRICA DOS MODELOS DE GESSOOBTIDOS COM SILICONE DE ADIÇÃO E SILICONE CONDENSAÇÃO,CRISTALIZADOS COM E SEM PRESSURIZAÇÃO. Niterói: Universidade Federal Fluminense, Faculdade de Odontologia; 2018.
Um estudo comparativo dos volumes de modelos obtidos sob ação de pressão ainda
é desconhecido.
O objetivo deste estudo foi avaliar as alterações dimensionais de modelos de gesso
obtidos com silicone de adição e condensação cristalizados sob ação de uma
máquina pressurizadora e de um vibrador.
Quarenta modelos de gesso foram obtidos a partir de moldagens, na técnica de
dupla moldagem, realizadas numa matriz de aço inoxidável e divididos em 4 Grupos:
silicone de adição sob pressão (SAP), silicone de adição com vibrador (SAV),
silicone de condensação sob pressão (SCP) e silicone de condensação com
vibrador (SCV), com 10 corpos de prova cada (n=10). Os grupos SAP e SCP foram
vazados e inseridos em uma máquina pressurizadora por 20 minutos. Os Grupos
SAV e SCV foram vazados utilizando um vibrador comum de bancada. O modelo
padrão e os modelos obtidos foram submetidos à medição em uma máquina por
coordenadas 3D. Os volumes obtidos da matriz de aço inoxidável e dos corpos de
prova foram comparados e submetidos a teste estatístico não paramétrico de
Kruskal-Wallis, ao nível de significância α = 0,05. O teste de Shapiro-Wilk foi
utilizado para verificar distribuição normal entre os grupos (p < 0,05).
Os resultados das medições dos corpos de provas deste estudo apresentaram
diferenças significantes quando comparados ao padrão. Os corpos de prova não
apresentaram diferenças significativas entre si. O volume do preparo parece estar
inversamente relacionado com a formação de bolhas.
Os modelos obtidos com silicone de condensação sob pressão (SCP) apresentaram
volumes mais próximos do padrão.
7
Neste estudo, a utilização da pressão na fase inicial da cristalização do gesso
forneceu modelos com medidas (volumes) mais próximas ao padrão independente
do material de moldagem utilizado.
Palavras-chave: modelos; precisão; materiais de moldagem; pressurização,
bolhas.
ABSTRACT
(Ferraz FF). A VOLUMETRIC COMPARISON OF PLASTER MOLDS OBTAINEDWITH VINYL POLYSILOXANE OR CONDENSATION SILICONE,CRYSTALLIZED WITH AND WITHOUT PRESSURIZATION.Niterói: Universidade Federal Fluminense, School of Dentistry; 2018.
A Comparative studies of volumes of molds obtained under the action of pressure
are still unknown.
This study volumetrically compared plaster models obtained with vinyl polysiloxane
or condensation silicone crystallized with and without pressurization.
Forty plaster models were obtained through double molding, performed in an array
of stainless steel (master model) and divided into 4 groups of 10 test specimens: (1)
Vinyl Polysiloxane under air pressure (VPSP), (2) Vinyl Polysiloxane with Vibrator
(VPSV), (3) Condensation Silicone under air pressure (CSP), (4) Condensation
Silicone with Vibrator (CSV). The VPSP and CSP groups were cast using a vibrator
and inserted in a pressurizing machine for 20 minutes. Both the master model and
the models obtained were submitted to measurements by a 3D Coordinate
Measuring Machine. The volumes obtained from the array of stainless steel and the
test specimens were compared and submitted to non-parametric Kruskal-Wallis
statistical test, with a significance of α = 0.05. The Shapiro-Wilk test was used to
verify the normality of groups (p < 0.05).
The four groups showed significant volumetric differences when compared to the
master model. The test specimens showed no significant differences between
themselves. The volume standard deviation of models obtained under positive
pressure were more homogeneous.
The use of positive pressure in the initial phase of the crystallization of plaster may
influence the volume of the model with measures which are more homogeneous,
regardless of the impression material used.
8
Keywords: models; precision; molding materials; pressurization, bubbles.
1 - INTRODUÇÃO
O conhecimento das características do material de moldagem na prática odon-
tológica é fundamental para o sucesso de uma prótese bem ajustada.1-3 O principal
objetivo das moldagens é reproduzir com precisão as estruturas dos tecidos duros e
moles intraorais em três dimensões.4
É de fundamental importância aplicar uma técnica de moldagem precisa,
pois ela determinará a longevidade das restaurações bem adaptadas, dificultando o
acúmulo de placa, micro-infiltrações, quebra de cimento e subsequente risco de
lesões cariosas e doença periodontal.5 O desajuste da prótese resultante pode
também levar à potenciais complicações biomecânicas devido ao estresse
excessivo.6-9
Nos últimos anos, as tecnologias digitais avançaram rapidamente. Isso
influenciou as transformações existentes na ciência, na indústria e no estilo de vida
diário.10,11 Inovações também surgiram na Odontologia,12 e mais recentemente, o uso
da impressão digital beneficiou o dentista e o paciente devido sua facilidade de
uso.13-16 No entanto, as técnicas de moldagem convencional com materiais
elastoméricos permanecem como as mais precisas e confiáveis.17,18
Os silicones do tipo adição estão entre os materiais mais dimensionalmente
precisos e estáveis disponíveis para procedimentos de moldagem em Odontologia.19-
23 As técnicas de moldagem com elastômeros podem ser classificadas como
monofásicas ou bifásicas. Vários autores relataram que a técnica bifásica é mais
precisa.24,25
Para obtenção de modelos das estruturas bucais e maxilofaciais, visando a
confecção de peças indiretas, principalmente na área de prótese, o gesso tem sido
um material amplamente utilizado na Odontologia.26 O processo de vazamento do
gesso no molde pode produzir alterações de superfície como aumento da
rugosidade e bolhas de ar. Moldes vazados sob pressão atmosférica são muito mais
9
propensos a apresentarem irregularidades superficiais. Além da utilização do
vibrador, o uso de pressão positiva pode ajudar a produzir modelos de gesso com
menos irregularidades na superfície.27-29
O presente estudo avaliou as alterações dimensionais de modelos de gesso
obtidos com silicone de adição e condensação, cristalizados com e sem
pressurização.
2 – MATERIAL E MÉTODOS
Uma matriz em aço inoxidável foi utilizada como modelo padrão, com base
retangular medindo 50,0mm de comprimento por 41,32mm de altura apoiando dois
pilares simulado preparos dentários de coroa total de um pré-molar (35) e um molar
(37), medindo respectivamente 478,0711mm3 e 818,6552mm3,respectivamente, e
moldeiras metálicas perfuradas, medindo 50,0mm de comprimento, 39,02mm de
altura e 6,52mm de largura, de acordo com as especificações da ISO 10360-230
(Figura 1).
O conjunto matriz em aço/moldeiras e placas foi desenhado e confeccionado por
um desenhista industrial, para adaptar, integrar, funcionar na dinâmica de um
verticulador BioArt (São Carlos–SP, Brasil), e garantir um posicionamento
padronizado, correto, livre de deslocamentos no momento das moldagens, conforme
metodologia descrita em trabalhos anteriores31 (Figura 2). Este equipamento foi
utilizado no Laboratório de Biotecnologia Aplicada (LABA) da Faculdade de
Odontologia da Universidade Federal Fluminense (UFF), Niterói, RJ/Brasil. O LABA
possui ambiente controlado, com estabilidade de temperatura (23 ± 2ºC) e de
umidade relativa do ar (50 ± 10%).
10
Figura 1 - Modelo padrão em aço inoxidável e moleira perfurada com sua base
Figura 2 – Modelo padrão posicionado na base e moldeira individualizada imobilizada na hastesuperior do verticulador BioArt sugerindo a cinemática do procedimento padronizado de moldagem.
Os grupos de material de moldagem e tamanho da amostra (n=10) representados
no Quadro 1, foram estabelecidos baseando-se em trabalhos similares de avaliação
de alterações dimensionais de materiais de moldagem e na ISO 4823.32
Quadro 1 – Grupos de materiais de moldagem e número de amostras.
Material de moldagem Grupo com pressurização Grupo sem pressurização
Elite® HD+ (Silicone por
adição)
10 amostras (SAP) 10 amostras (SCP)
Zetaplus (Silicone por
condensação)
10 amostras (SAV) 10 amostras (SCV)
11
SAP = silicone de adição sob pressão, SAV = silicone de adição com vibrador, SCP = silicone
de condensação sob pressão, SCV = silicone de condensação com vibrador.
Vinte moldes, 10 de cada (SAP e SAV), foram obtidos com silicone de adição (Elite
HD®+ Zhermarck® - Rovigo, Italy), na técnica de dupla moldagem, sem alívio, onde
inicialmente a base pesada e catalizador Putty Soft (Lote 205454, 2017.11) foram
manipulados, segundo instrução do fabricante. Após 3 minutos e 30 segundos a
moldeira foi removida do verticulador e da matriz em aço inoxidável para o segundo
passo com a base leve Light Body (Lote 91079, 2017.11) acoplada em uma
Dispensador Pistola DS-53 (Zhermarck® - Rovigo, Italy).
Os 20 moldes (SAP e SAV) foram armazenados em caixa umidificadora, à
temperatura ambiente (21oC), por 1 hora, respeitando o tempo de reação de
evaporação dos subprodutos voláteis na polimerização do silicone, antes de serem
vazados com gesso pedra especial tipo IV (Lote 1607053, 2019 .07, FujiRock® EP
GC - Alsip, USA). O gesso manipulado de acordo com instruções do fabricante
(água 20ml/pó 100g), levado a uma espatuladora a vácuo (Vac-U-Mixer - Whip-Mix
Corporation – Louisville, USA ) por 30 segundos e vazado sobre um vibrador de
bancada (DCLTM, Campinas - São Paulo, Brasil) com velocidade ajustada. O Grupo
SAP logo após vazado foi fechado e levado à máquina pressurizadora (CP-01 Caltini
- Curitiba-PR, Brasil), sendo mantido por 20 minutos com 6 bar de pressão,
conforme instruções do fabricante. O Grupo SAV cristalizou sob pressão
atmosférica. Depois uma 1 hora todos os 20 modelos SAP e SAV foram separados
de seus moldes.
Vinte moldes, 10 de cada (SCP e SCV), foram feitos com silicone de condensação
(Zetaplus, Zhermarck® - Rovigo – Italy, Lote 205061, 2017.11), na técnica de dupla
moldagem, sem alívio, misturados segundo instruções do fabricante. Esta mistura foi
inserida à moldeira personalizada e posicionada ao verticulador, onde foi realizada a
primeira fase da moldagem da matriz em aço inoxidável já posicionada no
verticulador por 3 minutos e 15 segundos. A moldeira foi removida do verticulador e
da matriz em aço inoxidável, para o segundo passo da moldagem com a base leve
Oranwash (Lote 203127, 2017.11) conforme instrução do fabricante.
Os moldes do grupo SCP foram vazados, fechados e levados à máquina
pressurizadora, sendo mantidos por 20 minutos com 6 bar de pressão, conforme
12
instruções do fabricante. O Grupo SCV cristalizou sob pressão atmosférica. Depois
uma 1 hora todos 20 modelos foram separados dos moldes.
Para avaliar a presença de bolhas nos modelos de gesso produzidos, dois
operadores cegos a natureza da pesquisa foram convidados para inspecionar todos
os modelos e registrar em uma planilha, graus para as bolhas observadas (Fig. 3).
Figura 3 – Exemplos de modelos classificados de acordo com as bolhas encontradas na superfície.Ausência de bolhas, 0; bolhas pequenas, 1 e bolhas grandes, 2.
O modelo padrão e os 40 corpos de prova foram identificados, numerados,
embalados e encaminhados 24 horas antes da medição, com a finalidade de
alcançar a estabilidade térmica, de acordo com a ISO 6873,198333, para medição no
Laboratório de Metrologia da empresa Mitutoyo Sul Americana Ltda, Suzano, SP,
Brasil; na Máquina de Medição por Coordenadas 3D, (Beyond-Crysta C 9168,
Mitutoyo, Kanagawa, Japão) com precisão de 0,00001mm ou 0,01µm, com
estabilidade de temperatura ambiente (23 ± 2°C) e de umidade relativa do ar (50 ±
10%).
Os modelos de gesso foram medidos após 7 dias de sua obtenção, quando
atingiram sua resistência ideal34.
A medição foi realizada pela sondagem de uma ponta de rubi (apalpador), em
pontos programados de forma a gerar imagem digital 3D. As medidas dos volumes
de cada cone foram registradas em uma planilha do Excel para análise estatística.
As análises estatísticas foram realizadas com o software IBM SPSS Statistics
V.22.0.0.0 for MAC, Armonk, NY; IBM Corp.
3 - ARGITO PRODUZIDO
A volumetric comparison of plaster molds obtained with vinyl polysiloxane or
condensation silicone, crystallized with and without pressurization.
13
Flávio Ferraz, MScD. Graduate Student, Department of Prostodontics, Universidade Federal
Fluminense School of Dentistry, Niterói, Rio de Janeiro, Brazil.
Waldimir Carvalho, MScD, PhD. Adjunct Professor, Department of Prostodontics,
Universidade Federal Fluminense School of Dentistry, Niterói, Rio de Janeiro, Brazil.
Vinicius Ferreira, MScD. Graduate Student, Department of Periodontics, Universidade
Federal Fluminense School of Dentistry, Niterói, Rio de Janeiro, Brazil.
Edgard Fonseca, MScD, PhD. Adjunct Professor, Department of Prostodontics, Universidade
Federal Fluminense School of Dentistry, Niterói, Rio de Janeiro, Brazil.
Eliane Porto Barboza, MScD, PhD. Professor, Department of Periodontics, Universidade
Federal Fluminense School of Dentistry, Niterói, Rio de Janeiro, Brazil.
Corresponding Author:
Eliane Porto Barboza.
Universidade Federal Fluminense School of Dentistry - Department of Periodontics.
Rua Mario Braga 30, Centro, Niterói, Rio de Janeiro, Brazil
CEP.: 24020-140
Tel.: 55 21 979808811
e-mail: [email protected]
ABSTRACT
Comparative studies of volumes of molds obtained under the action of pressure are still
unknown.
The purpose of this study wass to volumetrically compared plaster models obtained with
vinyl polysiloxane or condensation silicone crystallized with and without pressurization.
14
Forty plaster models were obtained through double molding, performed in an array of
stainless steel (master model) and divided into 4 groups of 10 test specimens: (1) Vinyl
Polysiloxane under air pressure (VPSP), (2) Vinyl Polysiloxane with Vibrator (VPSV), (3)
Condensation Silicone under air pressure (CSP), (4) Condensation Silicone with Vibrator
(CSV). The VPSP and CSP groups were cast using a vibrator and inserted in a pressurizing
machine for 20 minutes. Both the master model and the models obtained were submitted to
measurements by a 3D Coordinate Measuring Machine. The volumes obtained from the array
of stainless steel and the test specimens were compared and submitted to non-parametric
Kruskal-Wallis statistical test, with a significance of α = 0.05. The Shapiro-Wilk test was used
to verify the normality of groups (p < 0.05).
The four groups showed significant volumetric differences when compared to the master
model. The test specimens showed no significant differences between themselves. The
volume standard deviation of models obtained under positive pressure were more
homogeneous.
The use of positive pressure in the initial phase of the crystallization of plaster may influence
the volume of the model with measures which are more homogeneous, regardless of the
impression material used.
INTRODUCTION
The knowledge of the characteristics of impression material in dental practice is
essential for the success of a well-adjusted prosthesis.1-3 The main objective of reproduction
models is to accurately reproduce the structures of the intraoral hard and soft tissues in three
dimensions.4
It is essential to apply a precise molding technique, because it determines the
longevity of well adapted restorations, hampering the accumulation of plaque, micro-
15
infiltrations, breakage of cement and subsequent risk of carious lesions and periodontal
disease5. The misadjustment of the prosthesis may also lead to potential biomechanical
complications due to excessive stress.6-9
In recent years, digital technologies have advanced rapidly. This has influenced the
existing transformations in science, industry and in the style of daily life.10,11 Innovations have
also appeared in Dentistry,12 and more recently, the use of digital printing has benefited the
dentist and the patient due to its ease of use.13-16 However, conventional molding techniques
with elastomeric materials remain the most accurate and reliable.17,18
Vinyl polysiloxanes are among the more dimensionally accurate and stable materials
available for molding procedures in Dentistry.19-22 Molding techniques with elastomers can be
classified as either monophasic or biphasic. Several authors have reported that the biphasic
technique is more accurate.9,23-25
Plaster is a material that has been widely used in dentistry to obtain models of oral
and maxillofacial structures, aiming at the creation of indirect parts, mainly in the area of
prosthesis.26 The process of leakage from the plaster into the mold can produce changes such
as increased surface roughness and air bubbles. Casts set under atmospheric pressure are
much more likely to display surface irregularities. In addition to the use of the vibrator, the
use of positive pressure may help produce plaster models with fewer surface irregularities.27-29
This study volumetrically compared plaster models obtained with vinyl polysiloxane
or condensation silicone crystallized with and without pressurization.
MATERIAL AND METHODS
A standard model was constructed in stainless steel with rectangular base measuring
50.00 mm in length by 41.32 mm in height, simulating a premolar and a molar dental crown
16
preparations with volumetric areas of 478.07 mm3 and 818.65 mm3, respectively (Fig. 1),
manufactured according to the ISO 10360-2 specification.30
The set of casts and plates was designed and built to adapt, integrate and function in
the dynamics of a BioArt verticulator (São Carlos-SP, Brazil), guaranteeing a standardized
positioning, free of displacements during molding, according to methodology described in
other studies 31 (Fig. 2). This equipment was used in the Laboratory of Applied Biotechnology
(LABA) of the Faculty of Dentistry of the Fluminense Federal University. The LABA has a
controlled environment, with temperature stability (23±2ºC) and relative humidity (50±10%).
Figure 1 - Standard model in stainless steel and perforated miller with its base
Figure 2 - Standard model positioned on the base and individualized tray immobilized on the top stemof the BioArt verticulator suggesting the kinematics of the standard molding procedure.
17
The groups of impression material and sample size were established based on similar work of
evaluation of dimensional changes of molding materials and on ISO 4823 standard.32
Twenty casts of the matrix in stainless steel (master model) were obtained with vinyl
polysiloxane (Elite HD®+ Zhermarck® - Rovigo, Italy, Batch 205454, 2017.11). Twenty
casts were obtained with condensation silicone (Zetaplus, Zhermarck®, Rovigo, Italy, Batch
205061, 2017.11). Both techniques were biphasic, without relief, and manipulated according
to the manufacturer's instructions. The casts were stored in a moistening box, at ambient
temperature (21ºC), for 1 hour, observing the reaction time of evaporation of volatile by-
products in the polymerization of silicon, before being cast with Type IV Dental Die Stone
(FujiRock® EP GC, Alsip, USA, Batch 1607053, 2019 .07). The plaster was handled in
accordance with the manufacturer's instructions (water 20ml/100g powder), in a vacuum
spatulator (Vac-U-Mixer, Whip-Mix Corporation, Louisville, USA) for 30 seconds and poured
on a bench vibrator (DCLTM, Campinas, São Paulo, Brazil). Twenty casts (ten of vinyl
polysiloxane - VPSP group, and ten of condensation silicone – CSV group), immediately after
molding, were closed and taken to the pressurizing machine (CP-01 Caltini - Curitiba-PR,
Brazil), for 20 minutes with 6 bar pressure, according to the manufacturer's instructions.
Twenty casts (ten of vinyl polysiloxane - VPSV group, and ten of condensation silicone -
CSV group) were not placed into the pressurizing machine. The crystallization of plaster in
the CSV and VPSV groups was under atmospheric pressure. After 1 hour, all models were
separated from their casts.
In the plaster models, the presence or absence of bubbles and their diameters (Fig.3)
were evaluated by two operators blinded to the nature of the study who were invited to inspect
all models and register the collected data in a spreadsheet (0= absence of bubble, 1= bubbles
up to 1 mm, 2= bubbles above 1 mm). After the individual assessment, a consensus meeting
calibrated the obtained data to allow statistical analysis.
18
Figure 3 – Examples of models classified according to the bubbles found on the surface. Absence of
bubbles, 0; small bubbles, 1 and big bubbles, 2.
The master model and the 40 test specimens were identified, numbered, packaged
and shipped to the Metrology Laboratory (Mitutoyo Sul Americana Ltda, Suzano, SP, Brazil),
24 hours before the measurement, in order to reach thermal stability, according to ISO 6873,
1983.33 In the laboratory, a 3D Coordinate Measuring Machine (Beyond-Crysta C 9168,
Mitutoyo, Kanagawa, Japan) was used with an accuracy of 0.00001mm or 0.01μm, with room
temperature stability (23±2 °C) and relative humidity (50 ± 10%). Plaster models were
measured 7 days after their acquisition, when they reached their ideal resistance34. The
measurement was performed by probing a ruby tip (probe) at points programmed to generate
a 3D digital image. The measurements of the volumes of each cone were recorded in an Excel
spreadsheet for statistical analysis.
Statistical analyses were performed using the software IBM SPSS Statistics
V.22.0.0.0 for MAC, IBM Corp., Armonk, New York. All data were analyzed with the
Kruskal-Wallis test to assess significant differences among the groups (P<.05). As a post hoc
test, the Mann-Whitney U tests were also done to analyze the overall volumetric change
within the groups.
3 - RESULTS
Table 1 shows the volumes obtained by the measuring machine. Note how the
standard deviation of the groups placed in the pressurizing machine is lower than those that
only used the vibrator.
19
Table 1 – Measurements generated by the measuring machine in mm3
Table 1 – Measurements generated by the measuring machine in mm3
Molar Standard VPSP VPSV CSP CSV
1
818.6552
782.3145 789.2539 774.8159 749.9682
2 784.7547 797.6688 780.4662 831.4783
3 783.3422 744.0802 808.8574 774.6164
4 788.8775 794.8733 800.6277 806.9518
5 789.8637 793.0763 797.9710 741.5345
6 780.8350 792.9459 794.0392 789.2664
7 777.8658 782.2123 799.5846 755.9490
8 783.5533 710.3234 796.7057 788.7169
9 776.6554 782.7244 802.8329 775.0343
10 791.6577 778.2331 781.7885 729.7487
Average
783.9720 776.5392 793.7689 774.3264
SD 4.9714 27.8854 11.0391 31.1897
Premolar
Standard VPSP VPSV CSP CSV
1
478.0711
453.6177 463.1512 448.4713 433.2136
2 456.6980 469.5199 455.0288 475.6515
3 455.7146 417.6102 474.9895 449.6546
4 457.1877 465.8826 462.8572 471.9748
5 461.3133 463.6826 465.2682 431.3311
6 458.7451 465.2991 464.1430 461.6385
7 455.1724 457.5736 467.7178 443.6436
8 457.5581 433.9852 461.4491 463.4788
9 454.1969 455.8588 475.8820 452.4742
10 464.4242 460.9068 456.4835 430.8647
Average
457.4628 455.3470 463.2290 451.3925
SD 3.3225 16.5255 8.5466 16.6057
VPSP= vinyl polysiloxane under air pressure, VPSV= vinylpolysiloxane with vibrator, CSP= condensation silicone underpressure, CSV=condensation silicone with vibration. SD*- standard deviation.
20
The volumes of the VPSV groups did not present a normal distribution (Shapiro-Wilk test) in
molar (p=0.002) and pre-molar (p=0.004) casts. The measures of the other groups showed
normal distribution (p>.05). The VPSP, VPSV, CSP, CSV groups and the master model were
significantly different among themselves (p<0.05).
Figure 4 presents the comparative analyzes of volumes obtained for the molar preparations
between groups. Note the significant differences between the CSV groups and the master
model, VPSP and the master model and VPSV and the master model. Also note that there
were no statistical differences between the CSP group and the master model. Figure 5 presents
the comparative study of volumes obtained for the preparation of pre-molars among the
groups. Note that the master model volume showed significant differences when compared
with all the groups evaluated.
Figure 4 – results from multiple comparison between the analysed groups for molar
preparation volume.
21
Figure 5 – results from multiple comparison between the analysed groups for premolar
preparation volume.
Of the 80 models evaluated, 47.5% of the preparations did not present bubbles. Small
(26.25%) and large (26.25%) bubbles were observed in 52.5% of the models. Table 2 presents
the distribution of the bubbles per group. Statistical analysis did not show significant
differences between the bubbles evaluated within the groups (VPSP, VPSV, CSP, CSV) for the
molar and premolar preparations (P <.05).
Table 2 - Distribution of superficial bubbles
Table 2 – Distribution of superficial bubbles by group after consensus meeting
Samples Molar Premolar
VPSP VPSV CSP SCV ASP ASV CSP SCV
1 0 0 0 0 2 1 0 0
2 0 1 0 1 0 2 1 0
3 1 0 0 0 1 1 1 2
4 0 0 1 1 0 1 1 1
5 1 1 1 0 0 1 2 2
22
6 0 0 0 0 1 1 2 1
7 0 0 0 1 1 2 1 2
8 0 0 0 1 1 1 0 1
9 0 0 0 0 0 1 1 0
10 0 0 0 2 0 1 2 2
0= absence of bubbles, 1= small bubbles,2= big bubbles VPSP= vinyl polysiloxane under air pressure, VPSV= vinyl polysiloxanewith vibrator, CSP= condensation silicone under pressure, CSV= con-densation silicone with vibration.
DISCUSSION
Despite the constant advances in digitalization, reconstruction, 3D printing and the
manufacture of computer assisted dental prostheses, conventional moldings still represent the
most reliable model for copying of the buccal tissues required for the production of a well-
adapted prosthesis.17,18 Therefore, plaster models still play a fundamental role in the
manufacture of dental prostheses. This study compared the volumes of the stainless-steel
master model with plaster models obtained with vinyl polysiloxane or condensation silicone,
crystallized with and without pressurization. Other studies compared only the materials which
were tested.21,35 This creates a difficulty in verifying the significance of the differences
presented in the measurements of these studies. All groups of materials under pressure
produced significantly smaller models than the master model, simulating molar and pre-molar
preparations, except for the Condensation Silicone under air pressure (CSP) group in the
molar preparations. 2,22,24,36,37
The average volumes of the molar and pre-molar preparations of the Condensation
Silicone under air Pressure group (CSP) are closest to the volume of the Master Model.
Thereafter, the measurements presented a descending standard for the means of the Vinyl
Polysiloxane under air Pressure (VPSP), Vinyl Polysiloxane with Vibrator (VPSV) and
23
Condensation Silicone with Vibrator (SCV) groups. The only group that presented no
statistical difference when compared to the master model was the (CSP) for the molars (P =
0.106). Although the literature19-22 advocates that vinyl polysiloxane is the most accurate
molding material, the result of this work is in line with the study by Markovic et al, 20122
which showed that Condensation Silicone molds cast in 1 hour presented measurements
closer to the master model, compared to vinyl polysiloxane.
Previous studies stated that the use of pressure helps to produce smoother surfaces
and fewer irregularities.26,27 In the present study, the use of pressurization in the initial phase
of plaster crystallization seems to have influenced the best uniformity of the volumes. This
can be verified by the lower standard deviations presented by the groups submitted to pressure
when compared to those treated with a vibrator. There was a reduction of 51% and 35%
volume in Condensation Silicone groups with pre-molars and molars, respectively. The
reductions in Vinyl Polysiloxane groups were of 20% for pre-molars and 18% for molars.
Some studies point to an improved stability of Vinyl Polysiloxane compared to
other molding materials.19-22 This can be observed in the present study by the higher standard
deviation presented by the CSP and CSV groups in molars and pre-molars, compared to the
lower values presented by the VPSP and VPSV groups.
Despite of the differences in the values of the volumes obtained by the three-
dimensional models reconstruction by the 3D coordinate machine, there were no significant
differences between the groups VPSP, VPSV, CSP and CSV for molars and pre-molars.
In the present study, 40 models presented surface bubbles (52.5%). This may have
contributed to the reduction in the volume of the models due to the sensitivity of the Ruby tip
probe, used by the 3D Coordinate Measuring Machine.
The VPSP, VPSV, CSP and CSV groups did not present statistical differences
regarding the presence of bubbles, not allowing an attribution of causality to materials and the
24
use of pressure (Molar P = 0.054 and Pre-molar P = 0.516). This is in line with the in vitro
study of Machalakis et al., 200738 which showed that models obtained from polyether
produced plaster samples with less bubbles compared to polysiloxane. In addition, the use of
topical use of surfactants reduced the amount of bubbles in the silicone casts obtained by
addition silicone.39
In the present study it was possible to identify a tendency of greater homogeneity in
the models obtained with the action of positive pressure. However, further studies with a
larger number of samples are needed to verify the influence of pressure on the homogeneity of
the models volumes.
CONCLUSION
The use of positive pressure in the initial phase of the plaster crystallization may
influence the volume of the model with more homogeneous measurements, regardless of the
impression material.
Both Vinyl Polysiloxane and Condensation Silicone produced smaller models than
the Master Model, with or without the action of positive pressure.
The lower volume of the model does not seem to be related to the greater formation
of surface bubbles.
4- CONCLUSÃO
Os corpos de prova cristalizados sob pressão e somente com vibrador, deste
trabalho, mostraram ser dimensionalmente diferentes do modelo padrão.
Os corpos de prova não tiveram alterações dimensionais significativas em
entre si.
Neste estudo, a utilização da pressão na fase inicial da cristalização do gesso
forneceu modelos com medidas (volumes) mais próximas ao padrão
independente do material de moldagem utilizado.
O volume do preparo parece estar inversamente relacionado com a formação
de bolhas.
2
5 - REFERÊNCIAS BIBLIOGRÁFICAS
1. Donovan JE, Chee WW. A review of contemporary impression materials and
techniques. Dent Clin North Am 2004; 48 (2):445–70.
2. Marković D, Puškar T, Hadžistević M, Potran M, Blažić L, Hodolič J. TheDimensional Stabilty Of Elastomeric Dental Impression Materials.Contemporary Materials, III.1.2012: 105-110.
3. Matta RE, Adler W, Wichmann M, Heckmann SM, DMD. Accuracy ofimpression scanning compared with stone casts of implant impressions. JProsthet Dent. 2017;117:507-12.
4. Örtorp A, Jemt T, Bäck T: Photogrammetry and conventional impressions forrecording implant positions: a comparative laboratory study. Clin Implant DentRelat Res 2005;7:43-50.
5. Jamshidy L, Mozaffari HR, Faraji P, Sharifi R. Accuracy of the One-Stage andTwo-Stage Impression Techniques: A Comparative Analysis implantimpressions. Int J Dent. 2016, Nov 24. doi: 10.1155/2016/7256496.
6. Jemt T, Book K. Prosthesis misfit and marginal bone loss in edentu- lousimplant patients. Int J Oral Maxillofac Implants 1996;11:620–625.
7. al-Turki LE, Chai J, Lautenschlager EP, Hutten MC. Changes in prostheticscrew stability because of misfit of implant-supported prostheses. Int JProsthodont 2002;15:38–42.
8. Jansen VK, Conrads G, Richter EJ. Microbial leakage and marginal fit of theimplant-abutment interface. Int J Oral Maxillofac Implants 1997;12:527–540.
9. King GN, Hermann JS, Schoolfield JD, Buser D, Cochran DL. Influence of thesize of the microgap on crestal bone levels in non-submerged dental implants: Aradiographic study in the canine mandible. J Periodontol 2002;73:1111–1117.
10. Sharma S, Agarwal S, Sharma D, et al: Impression; digital vs. conventional:a review. Ann Dent Spec 2014;2:9-10.
11. Birnbaum NS, Aaronson HB: Dental impressions using 3D digital scanners:virtual becomes reality. Compend Contin Educ Dent 2008;29:494, 6, 8-505.
12. Lutz F, Krejci I, Mörmann W: Tooth-colored posterior restoration. Phillip JRestaurative Zahnmedizin. 1987;4:127-137).
3
13. Lee SJ, Macarthur RXt, Gallucci GO. An evaluation of student and clinicianperception of digital and conventional implant impressions. J Prosthet Dent2013;110:420-3.
14. Nayyar N, Yilmaz B, McGlumphy E. Using digitally coded healing abutmentsand an intraoral scanner to fabricate implant-supported, cement-retainedrestorations. J Prosthet Dent 2013;109:210-5.
15. Schepke U, Meijer HJ, Kerdijk W, Cune MS. Digital versus analog complete-arch impressions for single-unit premolar implant crowns: operating time andpatient preference. J Prosthet Dent 2015;114:403-6.
16. Park JM, Kim M, Heo SJ, Shin IH, Kim M. Comparison of experience curvesbetween two 3-dimensional intraoral scanners. J Prosthet Dent 2016;116:221-30.
17. Alsharbaty MHM,17 Alikhasi M , Zarrati S, Shamshiri AR. A ClinicalComparative Study of 3-Dimensional Accuracy between Digital andConventional Implant Impression Techniques. J Prosthodont. 2018 Feb 9. doi:10.1111/jopr.12764.
18. Basaki K, Alkumru H, De Souza G, Finer Y. Accuracy of Digital vsConventional Implant Impression Approach: A Three-Dimensional ComparativeIn Vitro Analysis. Int J Oral Maxillofac Implants. 2017 July/August;32(4):792–799. doi: 10.11607/jomi.5431.
19. Samet N, Shohat M, Livny A, Weiss EI. A clinical evaluation of fixed partialdenture impressions. J Prosthet Dent 2005;94:112- 7.
20. Hung SH, Purk JH, Tira DE, Eick JD. Accuracy of one-step versus two-stepputty wash addition silicone impression technique. J Prosthet Dent1992;67:583-9.
21. Chen SY, Liang WM, Chen FN. Factors af- fecting the accuracy ofelastometric impres- sion materials. J Dent 2004;32:603-9.
22. Pereira JR, Murata KY, Valle AL, Ghizoni JS, Shiratori FK. Lineardimensional changes in plaster die models using diferent elastomeric materials.Braz Oral Res 2010 jul-sep; 24(3):336-41.
23. Johnson GH, Craig RG. Accuracy of four types of rubber impressionmaterials compared with time of pour and repeat pour of models. J ProsthetDent 1985 Apr.; 53 (4): 484-90.
24. Millar BJ, Dunne SM, Robinson PB. In vitro study of the number of surfacedefects in monophase and two-phase addition silicone impressions. J ProsthetDent 1998;80:32-5.
25. Caputi S, Varvara G. Dimensional accuracy of resultant casts made by amonophase, one-step and two-step, and a novel two-step putty/light bodyimpression technique: An in vitro study. J Prosthet Dent. 2008; 99:274-281.
4
26. Walker MP, Rondeau M, Petrie C, Tasca A, Williams K. Surface quality andlong-term dimensional stability of current elastomeric impression materials afterdisinfection. J Prosthodont. 2007;16(5):343-51.
27. Bedi A, Michalakis KX, Hirayama H, Stark PC. The effect of differentinvestment techniques on the surface roughness and irregularities of goldpalladium alloy castings. J Prosthet Dent. 2008 Apr;99(4):282-6. doi:10.1016/S0022-3913(08)60062-1.
28. Tourah A, Moshaverinia A, Chee WW3. Effects of setting under air pressureon the number of surface pores and irregularities of dental investment materials.J Prosthet Dent. 2014 Feb;111(2):150-3. doi: 10.1016/j.prosdent.2013.06.014.Epub 2013 Nov 5.
29. Scrabeck JG, Eames WB, Hicks MJ. Spatulation methods and porosities ininvestments and impression material. J Prosthet Dent. 1986 Mar;55(3):332-4.
30. ISO 10360-2:2001, Geometrical Product Specifications (GPS) – Acceptanceand reverification tests for coordinate measuring machines (CMM) – Part 2:CMMs used for measuring size, ISO, 2001.
31. Valente VS, Zanetti AL, Feltrin PP, Inoue RT; Moura CDVS; Padua LEM.Dimensional Accuracy of Stone Casts Obtained with Multiple Pours into theSame Mold. International Scholarly Research Network Dentistry, v. 2012, p.730674-5, 2012.
32. International Standard Organization. ISO 6873. Dental Gypsum Product,1983.
33. ANSI/ADA Specification 19/ISO 4823:2000. Dental elastomeric impressionmaterials; Approved Apr 2004. Available at:https://siebel.ada.org/ecustomer_enu.start.swe?SWECmd=Start&SWEHo=siebel.ada.org.
34. Silva MAB, Vitti RP, Consani S, Sinhoreti MAC, Mesquita MF, Consani RLX.Linear dimensional change, compressive strengh and detail reproduction in typeIV dental stone dried at room temperetura end in a microwane ove. J Appl OralSci. 2012; 20(5): 588-593.
35. Garrofé AB, Ferrari BA, Picca M, Kaplan AE. Linear dimensional stability ofelastomeric impression materials over time. Acta Odontol Latinoam. Vol. 24 nº3, 2011; 289-294.
36. Raddy SM, Vijitha D, Karthikeyan, Balasubramanian R, Salish A. Evaluationof Dimensional Stability and Accuracy of Autoclavable Polyvinyl SiloxaneImpression Material. J Indian Prosthodontics Soc. 2012 Aug. dos10.1007/s13191-012-0168-z.
37. Lima LMS, Borges GA, Júnior LHB, Spohr AM. In vivo Study of theAccuracy of Dual-arch Impression. J of International Oral Health. 2014; 6(3); 50-55.
5
38. Machalakis KX, Bakopoupou A, Hirayama H, Garefis DP, Garefis PD. Pre-and Post-set Hydrophilicity of Elastomeric Impression Materials. Journal ofProsthodontics, July 2007, Vol. 16(4), pp.238-248.
39. Robinson PB, Dunne SM, Millar BJ. An in vitro study of a surface wetting
agent for addition reaction silicone impressions. Journal of Prosthodontics
Dentistry, 1994, Vol. 71(4), pp.390-393.