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Correlation between resonance frequency, insertion torque and bone-implant contact in self-cutting threaded implants

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Abstract

The aim of this study was to evaluate the correlation between resonance frequency analysis (RFA) values and the histomorphometric bone-implant contact (BIC) immediately after insertion of the implant. Additionally, it was examined to define which extent peak insertion torque (PIT) was correlated with the latter measurements. 15 Xive® S plus root from dental implants were inserted in fresh porcine frontal bones. The insertion torque was measured with the Kavo Intrasurg 300 surgical unit. RFA connector was coupled to the implants and the mean value of 20 consecutive RFA measurements was calculated via Osstell® ISQ device. The implants were removed with the adjacent bone with a band saw. The blocks were processed for undecalcified histology. Two perpendicular longitudinal middle sections of the implant were made and stained with toluidine blue and the BIC was assessed by histomorphometry. The correlation coefficient (Spearman) between RFA and BIC was R = 0.579 (p = 0.026, F test). The correlation between PIT and BIC (0.33, p > 0.05) and PIT and RFA (0.153, p > 0.05) was not statistically significant. The present data confirmed a moderate and statistically positive correlation between RFA and BIC. No correlation between BIC and PIT and PIT and RFA was observed. Further studies considering different bone qualities would be beneficial in understanding the relation between RFA and BIC.
1 23
Odontology
Official Journal of the Society of the
Nippon Dental University
ISSN 1618-1247
Odontology
DOI 10.1007/s10266-016-0265-2
Correlation between resonance frequency,
insertion torque and bone-implant contact
in self-cutting threaded implants
Yahya Açil, Jan Sievers, Aydin Gülses,
Mustafa Ayna, Jörg Wiltfang & Hendrik
Terheyden
1 23
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ORIGINAL ARTICLE
Correlation between resonance frequency, insertion torque
and bone-implant contact in self-cutting threaded implants
Yahya Ac¸il
1
Jan Sievers
2
Aydin Gu
¨lses
3
Mustafa Ayna
4
Jo
¨rg Wiltfang
1
Hendrik Terheyden
5
Received: 7 April 2016 / Accepted: 19 July 2016
ÓThe Society of The Nippon Dental University 2016
Abstract The aim of this study was to evaluate the cor-
relation between resonance frequency analysis (RFA) val-
ues and the histomorphometric bone-implant contact (BIC)
immediately after insertion of the implant. Additionally, it
was examined to define which extent peak insertion torque
(PIT) was correlated with the latter measurements. 15
Xive
Ò
S plus root from dental implants were inserted in
fresh porcine frontal bones. The insertion torque was
measured with the Kavo Intrasurg 300 surgical unit. RFA
connector was coupled to the implants and the mean value
of 20 consecutive RFA measurements was calculated via
Osstell
Ò
ISQ device. The implants were removed with the
adjacent bone with a band saw. The blocks were processed
for undecalcified histology. Two perpendicular longitudi-
nal middle sections of the implant were made and stained
with toluidine blue and the BIC was assessed by histo-
morphometry. The correlation coefficient (Spearman)
between RFA and BIC was R=0.579 (p=0.026, Ftest).
The correlation between PIT and BIC (0.33, p[0.05) and
PIT and RFA (0.153, p[0.05) was not statistically sig-
nificant. The present data confirmed a moderate and
statistically positive correlation between RFA and BIC. No
correlation between BIC and PIT and PIT and RFA was
observed. Further studies considering different bone qual-
ities would be beneficial in understanding the relation
between RFA and BIC.
Keywords Bone-implant contact Resonance frequency
analysis Insertion torque Primary stability Correlation
Immediate loading Dental implants Histomorphometric
measurements
Introduction
Resonance frequency analysis (RFA) basically measures
the acoustic behavior of the inserted implant body which in
turn is influenced by the bone contacts of the implant.
Despite the increasing use of RFA in the daily dental
practice, the reliability and validity of the method are still
controversial and, thus, it is an indirect measurement of the
implant stability which underlies a number of confounding
factors in the clinical situation. Because of the indirect
nature of the measurements, the clinical accuracy has to be
proven by correlations with either mechanical [peak
insertion torque (PIT)] or structural [bone-implant contact
(BIC)] variables. Similarly, Manresa et al. [1] have pro-
claimed that ISQ as determined by RFA is not able to
identify the relationship between RFA and histomorpho-
metrical data. It was also suggested that studies on the
accuracy and reliability of RFA are based mainly on
mechanical in vitro studies and are poorly supported by
histological measurements [2].
In the literature, several studies have demonstrated the
relation between PIT and the RFA [35]. PIT was con-
sidered to be clinically representative for primary implant
&Aydin Gu
¨lses
aydingulses@gmail.com
1
Department of Oral and Maxillofacial Surgery, Christian-
Albrecht-Universita
¨t zu Kiel, Kiel, Germany
2
Zahna
¨rztliche Gemeinschaftspraxis Dres., Isabelle und Jan
Sievers, Waiblingen, Germany
3
Gu
¨lhane Military Medical Academy, Centre of Dental
Sciences, Etlik Kec¸io
¨ren, 06010 Ankara, Turkey
4
Center for Implantology, Private Practice, Duisburg,
Germany
5
Clinic for Oral and Maxillofacial Surgery, Rotes Kreuz
Krankenhaus Kassel, Kassel, Germany
123
Odontology
DOI 10.1007/s10266-016-0265-2
Author's personal copy
stability. Although there is a strong correlation between
RFA and PIT, studies failed to find a correlation between
RFA and BIC or PIT and BIC (Table 1).
In the literature, there are controversies regarding the
interdependence of RFA and BIC [6,7]. Nkenke et al. [6]
have found a significant positive correlation of the existing
primary BIC with RFA in human fresh cadaver bone and
correlated RFA with PIT and BIC in conventional stepped
cylinder implants.
The threads of dental implants are representative of
macroscopic surface features that allow mechanical inter-
locking of implant within bone. The shape and depth of the
implant threads are determining factors in the aggressive-
ness of dental implants. The term ‘‘self-tapping’’ describes
an implant that cuts its own path into bone. Similarly, self-
cutting threaded implants are inserted in bone by a self-
cutting procedure by preparation of the implant bed
through cutting threads.
It is obvious that self-cutting threaded implants acquire
a higher primary stability in lower bone qualities through
the shape design of the relatively deep flanks of the
threads. However, the relation between RFA, PIT and BIC
in self-cutting threaded implants has not been evaluated
yet. The aim of the present study was to evaluate the
possible presence of a positive correlation between RFA,
BIC and PIT immediately after installation of self-cutting
threaded Xive
Ò
(Dentsply/Friadent Mannheim, Germany)
implants.
Materials and methods
The frontal bone of freshly slaughtered domestic pigs was
used as experimental subjects. The implant socket prepa-
rations were done by a single experienced implantologist.
15 sockets were created for 3.0 95.0 mm Xive
Ò
S plus
implants (Friadent GmbH Mannheim, Germany). The
quality of the bone was assessed by three different clini-
cians after performing osteotomies, close to the experi-
mental areas in a blinded mode.
The implants were placed according to the manufac-
turer’s guidelines. An independent observer, blinded to the
study, assessed the accuracy of placement. According to
the standard protocol of the manufacturer, in the first 3 mm
from the entrance to the implant socket, the threads were
pre-tapped. Before the insertion of the implants, drill holes
were thoroughly rinsed with saline to remove all bone
chips to prevent false-positive measurements of BIC.
Measurements
PIT
The PIT was recorded with the surgery unit Intrasurg 300
(KaVo Dental GmbH, Biberach/Riß, Germany). The value
was read from the display.
RFA
Osstell ISQ device (Integration Diagnostics AB, Go
¨teborg,
Sweden) was used to perform the RFA. Smart pegs were
coupled to the implants. The insertion torque for the smart
pegs where screwed is limited through a plastic wrench. 20
consecutive RFA measurements were made per implant
immediately after seating of the implant. The data were
stored in the device and the mean value was used for fur-
ther calculations.
BIC
The implants with at least 5 mm surrounding bone were
retrieved from the skull using the band saw. Then, the
blocks were dehydrated, embedded and processed accord-
ing to the sawing and grinding technology according to
Donath and Breuner [8].
The BIC was determined over the total length of the
implant. For this purpose, the implants were cut in half
longitudinally. Two longitudinal sections from the middle
of the implants were then made and examined from top to
tip. The remaining two halves of the implant were then
glued together again. Then, the implant was turned over
90°and the procedure was repeated so that another 2
longitudinal slices from the whole length of the implant
could be examined. With this method, we obtained 4 dif-
ferent longitudinal sections from different points of the
implant.
Table 1 Previous studies focusing on the comparison of RFA/BIC, IT/BIC and RFA/IT
Author Correlation RFA/BIC Value (p) Correlation IT/BIC Value (p) Correlation RFA/IT Value (p)
Nkenke et al. [6] Yes 0.024 – No 0.193
Scarano et al. [21] Yes 0.016 –
Degidi et al. [17] No 0.892 –
Ito et al. [11] No 0.299 –
Abrahamsson et al. [10]No – – – –
Kunnekel et al. [21]Yes –– ––
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BIC was measured histomorphometrically as follows:
by diaphanoscopy using the cold light lamp Schott KL
1500 (Schott AG, Mainz, Germany) the middle axis of the
implant within the tissue blocks was identified and marked.
A cut with the diamond band saw followed through the
middle of the implant in the longitudinal direction. Both
sides of the middles section were ground and polished to
high gloss with a sandpaper of grain 4000. For this pro-
cedure, *200 lm section through the middle diameter of
the implant was required to gain a 30–40 lm section for
the histology. After that, the two remaining halves of the
implants were glued back together with Loctite
Ò
493. The
glued block was rotated 90°and cut again lengthwise
according to the above-mentioned protocol to gain another
30–40 lm section for the histology. In this way, 2 verti-
cally oriented and perpendicular longitudinal sections of
30–40 lm thickness through the middle of the implant
were gained and a more appropriate field of observation for
BIC and the relative amounts of medullary vs. cortical
bone in hard tissue were achieved (Fig 1). The histological
slides were stained with toluidine blue.
The preparations were digitally photographed with the
Nikon photomicrography. With a magnification of 509,
the implant tissue interface and the bone interface of BIC
were assessed manually with the Leica
Ò
QWin Imaging
program.
Statistical analysis
The correlation between two variables (BIC–RFA, BIC–
PIT and RFA–PIT) was analyzed using Pearson correlation
coefficient, which is used to measure the strength of a
linear association between two variables, where the value
r=1 means a perfect positive correlation and the value
r=-1 means a perfect negative correlation. The coeffi-
cient r
2
was calculated to measure the validity of the cor-
relation estimates (0 Br
2
B1). An Ftest was calculated to
prove the significance of r
2
. A significance level of 0.05
was used.
Results
The histological overview over the 15 implants showed
that a bone-implant contact in the cortical area mainly
occurred at the edges of the threads, while in the cancellous
bone BIC was partly located in the valleys of the threads
(Figs. 2,3).
RFA–BIC
The correlation between RFA and BIC was statistically
significant (p=0.26). Figure 4shows the values as a
diagram. A positive correlation with less reliability towards
higher BIC values was observed (Table 2).
PIT–BIC
There was no statistically significant correlation between
PIT and BIC (p=0.398). The correlation was less than
that between the RFA and BIC (Fig. 5; Table 2).
PIT–RFA
There is a very weak correlation coefficient of 0.1529
between PIT and RFA. The Ftest failed due to lack of
power (Fig. 6; Table 2).
Discussion
RFA is applied clinically for the assessment of implant
stability, and the relevance of this application is widely
accepted. However, the relationship between RFA and
other parameters of implant stability, such as the histo-
morphometrical BIC parameter, has become controversial
in the last decade.
Kim and Lim [9] have indicated that the implant body
design without self-tapping blades has a good primary
stability compared with that with self-tapping blades in
Fig. 1 Arrangement of the 2 longitudinal sections perpendicular to
each other
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medium-density bone. Considering the RFA, a distinct
layer of cortical bone on marginal bone will yield implant
stability quotient values similar to those in medium-bone
density when implants have the same diameter. Similarly,
Kim et al. [10] have proclaimed that implants with an
aggressively deeper thread pattern without self-cutting
blades create a lateral compression with increased contact
surface area and, consequently, improve the primary sta-
bility in a simulated low-density bone model.
From a clinical point of view, Chowdary [11] have
stated that, implants without self-cutting thread design
showed more failures and bone loss than implants with
Fig. 2 Longitudinal section of the implant H section I (xive 3,
8913) after insertion in the OS frontale insertion torque: 45 NCM
(scale 12:1). The bone contact occurred mainly above the thread tips.
Measurement of BIC handed an enlargement of 950 out. The surface
of the implants could be assessed on the basis of four pictures per
implant
Fig. 3 Implant L cut I—inserted in the OS frontale with mostly
cancellous bone, insertion torque: 36 Ncm. (scale: 12:1)-bone contact
over long distances especially in the cancellous bone area. Bone chips
by abrasion could be well distinguished from intact tissues (left side).
The Harversian systems and the osteocytes were easy to find
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self-cutting thread design and indicated that self-cutting
thread tapered implant can be used safely and effectively
under demanding conditions as an immediate post-extrac-
tion tooth replacement. In addition, histological analysis of
probes indicates that self-cutting implants are associated
with a generally higher bone-to-implant contact pro-
nounced at the crestal part, when compared to preparation
of the bony implantation bed [12,13].
Although an aggressive implant with increased thread
depth provides a close contact between the implant and the
bone and, in general, provides high PIT, there are also
various studies enouncing that an excessive strain or
compression on the press-fit regions could exceed the
physiological limit and trigger bone resorption [14].
Bashutski et al. [14] have suggested that unusual implant
failures that likely occurred as a result of over compression
of the bone during placement and areas involving dense
bone seem to be at increased risk for compression necrosis.
In a canine study by Nevins et al. [15], several implant
designs and surgical technique modifications were inves-
tigated with the hypothesis of the design and site prepa-
ration changes would induce different compression states
on the native bone, by affecting the primary stability and
the rate and extent of osseointegration. They have tested
three compression scenarios, and have stated that the sce-
nario intended to induce a moderate degree of compression
provided the best overall results.
The controversies between these studies could be
attributed to the fact that during the use of a self-cutting
threaded implant, PIT undergoes several changes during
implant insertion [16]. The cutting feature in the apical
region increases the torque as it cuts a thread in the cortical
region and the insertion torque increases further during the
gradual transition in implant diameter, which is generated
by friction and static strain. Finally, when the cut thread in
the bone matches the implant thread, and no more expan-
sion is required, the insertion torque values even out [17].
Dagher et al. [18] have compared RFA, PIT, and BIC of
four different implant surfaces and evaluate the correlation
between them. According to their results, irrespective of
the implant surface, there is no correlation between PIT
and BIC and between RFA and BIC. There are also several
histomorphometric studies with controversial results
focusing on the evaluation of the correlation between BIC
and the RFA values [6,1921]. Similar to the results
obtained in the current study, Sacarano et al. [21] have
found a statistically significant correlation between RFA
and BIC values. Correlation of RFA and BIC immediately
after insertion was also examined by Nkenke et al. [6].
Although mathematically the correlation was positive and
significant in their study, looking upon data a great vari-
ability was obvious. They have stated that, clinically, the
RFA values still have to be used with caution.
Fig. 4 Relationship of resonance frequency values (ISQ) and bone-
implant contact (BIC): R-squared is 0.3349
Table 2 Correlation between resonance frequency analysis (RFA),
bone-implant contact (BIC) and peak insertion torque (PIT), the Ftest
to assess the significance could not be calculated for the PIT–RFA
because of the lack of power
Correlations RR
2
p
RFA–BIC 0.5787 0.3349 0.0263
PIT–BIC 0.3349 0.1122 0.3978
PIT–RFA 0.1529 0.0222 –
Fig. 5 Relationship between peak insertion torque (PIT) and bone-
implant contact (BIC), the R-squared is 0.1122
Fig. 6 Relationship between peak insertion torque (PIT) and reso-
nance frequency analysis (RFA): very weak correlation
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Clinically, PIT value of an implant is still an easily
accessible parameter to estimate implant stability for the
immediate loading protocols [2224]. In a review by
Esposito et al. [25], the importance of primary stability for
success of an immediately loaded loading of implants was
highlighted. In addition, for a reference period of up to
1 year, the initial PIT was considered to be representative
for primary stability [5,22,26,27]. The present experiment
showed only a weak and non-significant correlation
between BIC and PIT. This suggests that PIT should be
considered with caution to assess the primary stability. The
same conclusion can be found also in the current literature
in a study of Degidi comparing BIC and torque values [26].
The correlation between PIT and RFA is still not clear in
the literature.
There are a number of studies which found no statistically
significant correlation between the RFA and PIT. Akca et al.
[3] could not found any relationship between RFA and torque
in an in vitro study of 16 implants. Nkenke et al. [6] examined
the relationship between PIT and RFA at 48 implants in vitro
and found no statistically significant correlation. Also Degidi
et al. [17]andCehrelietal.[28] found no correlation between
the two values. Degidi et al. [26] suspected a larger influence
of bone structure to the torque as the RFA values. Also in the
current study, no statistically significant correlation could be
found between PIT and RFA values.
Although there are differences in bone density and
quality between humans and the various animal models,
pigs represent a comparable osseous macro- and
microstructure behavior in comparison to humans [2931].
As shown in Figs. 2and 3, the selected recipient site for
implant insertions could also present differences in bone
quality. Nevertheless, considering the limited depth and
thick compacta within the forehead of the domestic pig,
current model could be representative for the implant
recipient sites at the posterior mandible in humans. This
means that, immediately after insertion of the implant,
already relaxation will take place. This can affect the ISQ
measurements as well as bone contact measurements.
Besides that, it is well known that, ISQ measurements as
well as bone contact measurements could also be affected
by the visco-elastic behavior of the bone and possible
concomitant relaxation, which takes place immediately
after insertion of the implant. Additional studies with dif-
ferent bone types could also be beneficial in understanding
the correlation between RFA, BIC and PIT.
Conclusion
The present data confirmed a moderate and statistically
positive correlation between RFA and BIC. No correlation
between BIC and PIT and PIT and RFA was observed.
Further studies within the varying times of healing periods
representing commonly used protocols for early and delayed
implant loading protocols would be beneficial for gaining
understanding of the bone remodeling characteristics.
Acknowledgments We gratefully acknowledge Grabriele Neßenius
for her assistance in the plastic embedding procedure and the pro-
duction of tissue slides. We also acknowledge Eylem Ugur Gu
¨lses for
conducting the statistical analysis of the manuscript. The manuscript
has been language edited by professional interpreter Ms. Serpil
Tu
¨regu
¨n.
Compliance with ethical standards
Conflict of interest The authors declare that they have no conflict of
interest.
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Odontology
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... In order to increase primary stability, a thread design is used for most commercial implants, and a torque of 30-60 Ncm is needed to screw the implant into the prepared cavity during implantation [34]. Clinicians also use adaptive drilling procedures and bone condensing technology in implant surgery [35,36]. Here, the diameter of the prepared cavity is slightly smaller than that of the implant (~0.5 mm) for intimate bone-to-implant contact. ...
Article
Typical strategies used to improve the osteo-inductive and antioxidative capacities of titanium and its alloys involve loading with functional molecules, such as proanthocyanidin (PAC), by physical adsorption, which limits the bonding strength and durability of the coating. Accordingly, in the present study, (3-aminopropyl) triethoxysilane (APTES) and glutaraldehyde (GA) were used to prepare covalently immobilized PAC and chitosan-encapsulated PAC (CS-PAC) coatings on Ti surface. Quantum chemistry and X-ray photoelectron spectroscopy analyses confirmed the chemical grafting of PAC and CS-PAC onto the Ti surfaces. Their superior wear and compression resistances were demonstrated by friction and nanoindentation testing. SEM observation of the surface revealed that the improvement of mechanical properties is not only related to the formation of chemical bonds, but also to the presence of nanoparticles that act as roller bearings. Contact angle measurement and TEM observation were also used for surface analysis. The murine pre-osteoblast cell line MC3T3-E1 was used to assess the osteo-inductive and antioxidative activities of the coatings under H2O2-induced oxidative stress in vitro. The cell-adhesion-, proliferation-, and differentiation-promoting properties as well as antioxidant properties of PAC are retained after the formation of chemical bonds to APTES. Thus, this silane coupling strategy can enhance the mechanical properties of PAC nanocoatings while preserving their biological activity.
... Figura 3: Equipamiento marca Osstell ® [37] Sin embargo, la RFA no se puede utilizar para identificar directamente las características de la interfaz hueso-implante [38] . Se ha demostrado una correlación moderada y estadísticamente positiva entre RFA y BIC (contacto hueso-implante) [39] . En algunos trabajos se concluyó que incluso si la relación entre la estructura ósea y la RFA todavía no se comprende completamente, se encontró una correlación estadísticamente significativa entre los valores de RFA y BIC [40] . ...
Research
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Objetivo: El objetivo de este estudio fue verificar la prueba de ultrasonido en distintos modelos in-vitro para valorar la estabilidad de los implantes. Materiales y Métodos: Se realizó un trabajo experimental in-vitro desde abril de 2018 hasta junio de 2019. Se insertaron 5 implantes de 3 modelos de implantes diferentes (cónicos de Biomet 3i®, de paredes paralelas de Biomet 3i® y cilíndrico de ByW®) de diámetro 4 y 5mm y de 10 y 13 mm de longitud, en 3 modelos experimentales de materiales diferentes: - Cilindro de resina fenol-formaldehído, - Modelo de maxilar inferior sintético, elaborado con resina fenólica, y- hueso porcino fresco. Luego se utilizó la técnica de ultrasonido “Pulso-Eco” con palpadores de 6MHz de frecuencia de resonancia colocados en la cabeza de implante para valorar la estabilidad de interfaz implante / material. Este procedimiento de realizó inmediatamente a la inserción del implante en el material y posterior a la aplicación de una carga de Resumen compresión al conjunto, dichas cargas aplicadas variaron según el material en donde se realizó la inserción. Las mismas tomaron valores en 0,2 kN y 2,5 kN. Los datos fueron recolectados para análisis estadístico básico de los datos, con el software Matlab®. Resultados: Las gráficas de ultrasonidos pulso-eco obtenidas en todos implantes inmediatos a la colocación (previo a la carga de compresión), fueron bastante similares, evidenciando una correcta adhesión entre el implante y el material símil hueso en el que se realizó la inserción. En cambio, una vez que se realizó el ensayo con una fuerte carga de compresión al conjunto, las cargas de compresión tomaron valores superiores a los 2,5 kN. Las gráficas de ultrasonidos de los conjuntos implante + material símil hueso e implante + hueso mostraron resultados bastante diferentes, pudiéndose apreciar los picos del extremo del implante, y del fondo del material de soporte (resina, material sintético o hueso, según el caso). Las diferencias en los resultados son consecuencia de que el esfuerzo aplicado produjo fisuras en la zona de la interfase material símil hueso / implante dental, lo cual hace que las ondas ultrasónicas no se puedan propagar adecuadamente, como es el caso de los implantes recién colocados. Conclusión: Luego de someter las muestras a inspección mediante la técnica de pulso- eco por ultrasonidos, antes y después de la aplicación de un importante esfuerzo de compresión, los resultados mostraron una importante diferencia en las curvas ultrasónicas para cada situación, dejando en evidencia que la pérdida de estabilidad primaria de la muestra sometida a un esfuerzo excesivo, puede ser determinada mediante la relacionada técnica. Se comprueba las ventajas de la utilización de la técnica de ultrasonidos, puesto que la misma permitiría determinar la pérdida de estabilidad del conjunto hueso-implante dental, producida, por ejemplo, por la actividad de masticación de un paciente, con un esfuerzo importante.
... nor between PIT and RFA (P = .153). 17 However, these studies are in vitro studies, and therefore, the results obtained need to be confirmed by clinical studies. The most similar study to the present study was conducted by Kahraman et al. 18 These authors treated 13 partially edentulous subjects, inserting 43 implants and using a two-stage technique. ...
Article
Purpose: Primary stability is the most important prognostic index for predicting osseointegration. It is generally thought that to achieve high primary stability, it is necessary to insert an implant with a high insertion torque (IT). To date, it has not yet been determined whether IT and implant stability quotient (ISQ) values are correlated. The primary aim of the study was to determine the correlation between IT and ISQ values at the time of implant insertion (T0); at 2 months, the time of healing (T1); and at 6 (T2) and 12 months (T3) after loading. The secondary aims were to determine the influence of different macroscopic implant designs and of a different insertion arch on this correlation; and to assess whether implants inserted with a high IT, that is, > 50 Ncm, had higher levels of implant stability at 2-, 6-, and 12-month follow-ups. Materials and methods: STROBE guidelines were followed. Partially or monoedentulous patients were randomly assigned to receive taper thread on straight-body implants with microthreads (group A) or without microthreads (group B). At implant insertion, IT and ISQ values were recorded. At 2-, 6-, and 12-month follow-ups, the ISQ values were recorded. A spring-style torque wrench was used to assess the IT. The Osstell device was used to determine the ISQ values. Descriptive statistics, Pearson correlation, and t test were used. P was set at ≤ .005. Results: Two hundred fifty subjects were assessed; 142 were included. Two hundred sixty-eight implants were inserted (group A, 137 implants; group B, 131 implants). No subject dropped out, and no implant failed. A statistically significant correlation between ISQ and IT was determined at the time of implant insertion (T0; P = .000). The implant morphology and arch did not influence the correlation. An IT > 50 did not determine a higher secondary stability. Conclusion: There is a strong correlation between IT and primary stability, but IT is not correlated with the secondary stability. A different implant macroscopic design and a different arch of insertion did not influence this correlation. Moreover, implants inserted with IT > 50 Ncm do not result in greater secondary stability.
... In the current experimental model, the quantification of the healing process and the connections between implants and bone were assessed via BIC, ITBD, and PBD. Those parameters were used as markers for osseointegration in several studies [19,20]. According to Bernhardt et al., these parameters could appropriately describe the osteogenic potential of the implant surfaces [21]. ...
Article
Full-text available
Abstract: Background and Objectives: The aim of the current study was to establish an osseo-disintegration model initiated with a single microorganism in mini-pigs. Materials and Methods: A total of 36 titanium dental implants (3.5 mm in diameter, 9.5 mm in length) was inserted into frontal bone (n: 12) and the basis of the corpus mandible (n: 24). Eighteen implants were contaminated via inoculation of Enterococcus faecalis. Six weeks after implant insertion, bone-to-implant contact (BIC) ratio, interthread bone density (ITBD), and peri-implant bone density (PIBD) were examined. In addition to that, new bone formation was assessed via fluorescence microscopy, histomorphometry, and light microscop-ical examinations. Results: Compared to the sterile implants, the contaminated implants showed significantly reduced BIC (p < 0.001), ITBD (p < 0.001), and PBD (p < 0.001) values. Around the sterile implants, the green and red fluorophores were overlapping and surrounding the implant without gaps, indicating healthy bone growth on the implant surface, whereas contaminated implants were surrounded by connective tissue. Conclusions: The current experimental model could be a feasible option to realize a significant alteration of dental-implant osseointegration and examine novel surface decontamination techniques without impairing local and systemic inflammatory complications.
... In contrast to our findings, those of Acil and his group revealed no correlation between peak IT and RFA in self-cutting implants in a porcine bone model [26]. Degidi et al. clinically examined 4135 implants and found a low correlation between RFA and IT. ...
Article
Full-text available
Our aim was to analyze the correlation between the IT evaluated by a surgical motor and the primary implant stability (ISQ) measured by two RFA devices, Osstell and Penguin, in an in vitro model. This study examines the effect of bone type (soft or dense), implant length (13 mm or 8 mm), and implant design (CC: conical connection; IH: internal hexagon), on this correlation. Ninety-six implants were inserted using a surgical motor (IT) into two types of synthetic foam blocks. Initial measurements for both the peak IT and ISQ were recorded at the point when implant insertion was stopped by the surgical motor, and the final measurements were recorded when the implant was completely inserted into the synthetic blocks using only the RFA devices. Our null hypothesis was that there is a good correlation between the devices, independent of the implant length, design, or bone type. We found a positive, significant correlation between the IT, and the Osstell and Penguin devices. Implant length and bone type did not affect this correlation. The correlation between the devices in the CC design was maintained; however, in the IH design it was maintained only between the RFA devices. We concluded that there is a high positive correlation between the IT and ISQ from a mechanical perspective, which was not affected by bone type or implant length but was affected by the implant design.
... Clinical validity was implemented using the histological classification of bone density at the implant recipient site. The tissue samples were evaluated according to the technique described by Donath and Breuner 13 and later developed by Açil et al. 14,15 Briefly, tissue samples were placed into 10% neutral buffered formalin for fixation for 4 days and embedded in methacrylate prior to sawing and grinding. Sawing and grinding were performed, and the samples were placed in glass vessels filled with monometric resin solution and incubated at 378C to 408C for 2 to 4 days for resin impregnation. ...
Article
Straumann ® BLX is a novel implant system, which has been proclaimed to provide an ideal primary stability in all types of bone. In the current study, the primary stability of Straumann ® BLX implant systems with Straumann ® tapered effect (TE) implants have been comparatively assessed in bovine ribs by using a simultaneous sinus elevation and implant insertion model. In the study group, BLX (4.0 x 12 mm), TE (4.1 x 12 mm), BLX (4,5 x 12 mm) and TE (4.8 x 12 mm) were placed in each bony window, which resembles sinus maxillaris. As a control, BLX and TE implants with same sizes were inserted into the proximal diaphysis of the bovine ribs. A total of 40 implant insertions were performed. The stability was measured with resonance frequence analysis. In the study group, TE implants of 4.8 mm showed significantly higher values compared to 4.5 mm BLX implants (p=0.116). However, BLX implants of 4.0 mm in the control group showed higher stability compared to TE with 4.0 mm diameter. (p=0.014). The primary stability of BLX implants in the control group was significantly higher compared to the experimental group in both widths (p=0.018 for BLX 4.0 and p=0.002 for BLX 4.5 respectively). The use of TE design with wide diameter in simultaneous implant placement with sinus lift could present higher ISQ values and might be more appropriate option for implant recipient sites with poor bone volume and quality. However, the advantage of BLX design in standard implant insertion protocols could be precious.
... The tissue samples were histologically evaluated according to the technique described by Donath et al. [16] and later developed by Acil et al. [17,18]. Briefly, tissue samples were placed into 10% neutral buffered formalin (NBF) for fixation for 4 days and embedded in methacrylate prior to sawing and grinding. ...
Article
Full-text available
Background: The aim of the current study was to comparatively assess the primary stability of different Straumann® implant designs (BLX, Straumann Tapered Effect, Bone Level Tapered, and Standard Plus) via resonance frequency analysis by using an implant insertion model in freshly slaughtered bovine ribs with and without cortical bone. Tapered Effect (4.1 × 10 mm), Bone Level Tapered (4.1 × 10 mm), Standard Plus (4.1 × 10 mm), and BLX (4.0 × 10 mm) implants were inserted into the distal epiphysis on the longitudinal axis of the freshly slaughtered bovine ribs. As a control, implants with the same sizes were inserted into the proximal diaphysis. The stability of the implants was examined with resonance frequency analysis. Results: BLX and Tapered Effect implants showed higher implant stability quotient values in both study and control groups. All implant systems showed a significant decrease of mechanical anchorage in the study group. BLX and Bone Level Tapered designs had a significantly lower loss of mechanical anchorage in the lack of cortical bone. Conclusion: Both Tapered Effect and BLX designs could ensure sufficient initial stability; however, BLX implants could be an appropriate option in the lack of cortical bone and poor bone quality at the implant recipient site. Clinical relevance: BLX is a novel implant system, which could be especially beneficial in the presence of spongious bone type at posterior maxillae.
Thesis
While surgical interventions involving the use of endosseous implants are now routinely performed, failures still occur and may have dramatic consequences. The clinical outcome depends on osseointegration processes, which correspond to the growth of bone in intimate contact with the implant. This work focuses on the development of quantitative ultrasound (QUS) techniques for the characterization of the biomechanical properties of the bone-implant interface (BII), which are the main determinant for the success of osseointegration.First, an in vitro approach is carried out to assess the sensitivity of the QUS response of the BII to loading conditions. Trabecular bovine bone samples are compressed onto coin-shaped implants and the ultrasonic response of the BII is measured during compression. A significant decrease of the reflection coefficient of the BII as a function of the stress is obtained until a plateau is reached, corresponding to bone fracture.Second, finite element modeling and simulations are performed in order to distinguish the effects of different parameters on the ultrasonic response of the BII. In particular, the impact of the implant surface roughness is investigated at the microscopic and macroscopic scales. An analytical model of the ultrasonic propagation at the BII is also proposed. The reflection coefficient of the BII is shown to significantly decrease when (i) the BII is better osseointegrated, (ii) the roughness amplitude decreases, (iii) the central frequency of ultrasound decreases and (iv) bone mass density increases. Moreover, interference phenomena are evidenced at the macroscopic scale.Third, in silico, in vitro and in vivo studies are combined to investigate the use of QUS methods to estimate dental implant stability. Ultrasound propagation inside a dental implant is examined using laser-interferometric techniques. First arriving signal and spectral analyses evidence the propagation of a guided wave mode along the implant axis, which is confirmed by numerical simulation. An in vivo study is performed to compare the performances of QUS and of resonance frequency analysis to estimate dental implant stability in a rabbit model. The QUS results were shown to have a better sensitivity to changes of bone quantity and quality during the osseointegration processes.By coupling experimental and numerical approaches, this work provides new insights to better understand the propagation of ultrasonic waves at the BII. Moreover, it proves the performances of a future medical device that could assess dental implant stability.
Article
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ABSTRACT The aim was to: (i) compare changes among primary and secondary implant stability between immediate and early loaded implants in edentulous maxilla, (ii) evaluate oral health related quality of life (OHRQoL) and (iii) determine patient satisfaction with 6-implant supported fixed full-arch dentures. A prospective, randomized controlled clinical trial was conducted on 24 edentulous maxilla patients. The BLT SLActive® implants in 12 patients were immediately loaded with temporary restorations while12 patients did not receive temporary restorations. Definitive (final) dentures were delivered to all patients after 6 weeks. Stability of the implants were assessed by Insertion Torque (IT) and Resonance Frequency Analysis (RFA). Oral Health Impact Profile-19 ( OHIP-19) questionnaire was used to evaluate OHRQoL and a Visual Analogue Scale (VAS) for patient satisfaction. The IT value of implants assigned for immediate and early loading group was 27.17±9.55Ncm and 25.01±11.06Ncm, respectively. Changes in implant stability from baseline to week 6 were similar in both groups when measured by Penguin ® (p=0.881) and Ostell ® (p= 0.828). Patients in the immediate load group reported significantly lower OHIP physical pain scores (p=0.016), OHIP psychological disability score (p=0.046) and significantly higher VAS function score (p=0.009) and VAS aesthetics score (p=0.009). Implant loading protocols don't have a significant effect on the change in implant stability 6 weeks after implantation, however, immediate loading significantly improves OHRQoL and satisfaction of patients with maxillary edentulism treated by fixed full-arch dentures. Future trials will determine the role of immediate loading protocol in clinical scenarios with various amounts of available jaw bone using different numbers of implants to retain a fixed prosthetic restoration in the edentulous maxilla.
Article
Background: The ideal installation technique or implant macrogeometry for obtaining an adequate osseointegration in low-density bone tissue follows a challenge in the implantology. Aims and objective: The aim of the present study was to evaluate the behavior of three osteotomy techniques and two implant macrogeometries in two low-density polyurethane blocks. The insertion torque (IT), initial stability, pullout resistance, and weight of the residual bone material deposited on the implants were assessed. Materials and methods: A total of 120 implants with two different macrogeometries were used. They were divided into six groups according to the implant macrogeometry and the drilling technique performed (n = 20 implants per group). The implants were installed in polyurethane blocks with pounds per cubic foot (PCF) 10 and PCF 20 densities. The IT, initial stability, pullout resistance, and weight residual bone were measured. Results: Differences were found in the values referring to the macrogeometry of the implants and the type of osteotomy performed. In all groups, the initial stability of the PCF 10 blocks was quite low. The undersized osteotomies significantly increased the values measured in all tests in the PCF 20 density blocks. Conclusions: In conclusion, even when a modified (undersized) osteotomy technique is used, implants inserted in low-quality bone (type IV) can present problems for osseointegration due their low initial stability and bone resistance. However, the modification in the implant macrogeometry (with healing chambers) presented more quantity of bone on the surface after the pullout test.
Article
Introduction: Primary stability is evaluated using resonance frequency analysis (RFA) and insertion torque (IT). Although there is a strong correlation between RFA and IT, studies failed to find a correlation between RFA and bone to implant contact (BIC) or IT and BIC. Objective: To compare RFA, IT, and BIC of SLA, SLActive, Euroteknika, and TiUnite implant surfaces and evaluate the correlation between them. Materials and methods: Thirty-two implants were placed in 8 sheep. RFA and IT were recorded. Animals were killed at 1 and 2 months. Results: A significant difference was found in RFA between the 4 surfaces. No significant difference was found for IT. Mean BIC was different between all 4 surfaces. A significant positive correlation was found between RFA and IT with SLA. No significant correlation was found between RFA and BIC and between IT and BIC at 1 and 2 months. Conclusions: Implants with 4 different surfaces have similar IT values but different RFA and BIC. Additionally irrespective of the implant surface, there is no correlation between IT and BIC and between RFA and BIC.
Article
Information concerning the effects of the implant cutting flute design on initial stability and its influence on osseointegration in vivo is limited. This study evaluated the early effects of implants with a specific cutting flute design placed in the sheep mandible. Forty-eight dental implants with two different macro-geometries (24 with a specific cutting flute design – Blossom group; 24 with a self-tapping design – DT group) were inserted into the mandibular bodies of six sheep; the maximum insertion torque was recorded. Samples were retrieved and processed for histomorphometric analysis after 3 and 6 weeks. The mean insertion torque was lower for Blossom implants (P < 0.001). No differences in histomorphometric results were observed between the groups. At 3 weeks, P = 0.58 for bone-to-implant contact (BIC) and P = 0.52 for bone area fraction occupied (BAFO); at 6 weeks, P = 0.55 for BIC and P = 0.45 for BAFO. While no histomorphometric differences were observed, ground sections showed different healing patterns between the implants, with better peri-implant bone organization around those with the specific cutting flute design (Blossom group). Implants with the modified cutting flute design had a significantly reduced insertion torque compared to the DT implants with a traditional cutting thread, and resulted in a different healing pattern.
Article
Promising biomaterial characteristics of diamond-coatings in biomedicine have been described in the literature. However, there is a lack of knowledge about implant osseointegration of this surface modification compared to the currently used sandblasted acid-etched Ti-Al6-V4 implants. The aim of this study was to investigate the osseointegration of microwave plasma-chemical-vapour deposition (MWP-CVD) diamond-coated Ti-Al6-V4 dental implants after healing periods of 2 and 5 months. Twenty-four MWP-CVD diamond-coated and 24 un-coated dental titanium-alloy implants (Ankylos(®)) were placed in the frontal skull of eight adult domestic pigs. To evaluate the effects of the nano-structured surfaces on bone formation, a histomorphometric analysis was performed after 2 and 5 months of implant healing. Histomorphometry analysed the bone-to-implant contact (BIC). No significant difference in BIC for the diamond-coated implants in comparison to reference implants could be observed for both healing periods. Scanning electron microscopy revealed an adequate interface between the bone and the diamond surface. No delamination or particle-dissociation due to shearing forces could be detected. In this study, diamond-coated dental titanium-alloy implants and sandblasted acid-etched implants showed a comparable degree of osseointegration.
Article
The dental community's interest in early loading of endosseous implants provides the stimulation to test the ability of modified implant designs as well as surgical techniques to enhance the establishment and maintenance of implant stability. This preclinical canine study examined this potential by implementing several implant design and surgical technique modifications to an existing tapered implant system. The design and site preparation changes were intended to induce different compression states on the native bone, hypothetically affecting the primary stability and the rate and extent of osseointegration. The outcomes of the modifications were evaluated using resonance frequency analysis, radiographic analysis, light microscopy, and histomorphometric measurements. Three compression scenarios were tested, with each demonstrating excellent clinical, radiographic, and histologic results throughout the evaluation period. However, the scenario intended to induce a moderate degree of compression provided the best overall results, supporting its use in early loading protocols.
Article
Background The treatment of patients with early or immediately loaded dental implants has renewed interest in the behavior of osseointegration at the implant surface. Whereas it is generally accepted that peri-implant tissue formation and mineralization are dependent on the local mechanical environment in the interface zone, controversies exist concerning the impact of implant design on peri-implant bone formation. The aim of the present study was the in vivo evaluation of peri-implant bone formation by two different implant systems: cylindrical (ITI) versus conical (ILI). Material and method A total of 60 implants (30 ITI and 30 ILI) were placed in the cranial and caudal part of the tibia of eight Göttinger minipigs. Half of the minipigs were sacrificed at 7 days and 28 days of osseointegration. Implant-containing bone specimens were prepared for histological and ultrastructural investigations. Results Histological and scanning electron-microscopic investigations showed a direct contact of bone-like minerals over the whole implant surface from day 7 of implant/bone interaction. Whereas the ILI implant showed direct contact up to the top of the crestal bone, ITI implants demonstrated a crestally located narrow gap without ossification over the whole experimental period. Conclusion Our investigations support the hypothesis of an implant design-inherent emergence and maintenance of crestal bone.
Article
Bone remodeling is a process involving both dynamic and static bone strain. Although there exist numerous studies on the effect of dynamic strain on implant stability and bone remodeling, the effect of static strain has yet to be clarified. Hence, for this purpose, the effect of static bone strain on implant stability and bone remodeling was investigated in rabbits. Based on Finite Element (FE) simulation two different test implants, with a diametrical increase of 0.15 mm (group A) and 0.05 mm (group B) creating static strains in the bone of 0.045 and 0.015 respectively, were inserted in the femur (group A) and the proximal tibia metaphysis (groups A and B respectively) of 14 rabbits to observe the biological response. Both groups were compared to control implants, with no diametrical increase (group C), which were placed in the opposite leg. At the time of surgery, the insertion torque (ITQ) was measured to represent the initial stability. The rabbits were euthanized after 24 days and the removal torque (RTQ) was measured to analyze the effect on implant stability and bone remodeling. The mean ITQ value was significantly higher for both groups A and B compared to group C regardless of the bone type. The RTQ value was significantly higher in tibia for groups A and B compared to group C while group A placed in femur presented no significant difference compared to group C. The results suggest that increased static strain in the bone not only creates higher implant stability at the time of insertion, but also generates increased implant stability throughout the observation period.
Article
This study tested the hypothesis that there would be differences in primary stability due to the presence of self cutting blades. We investigated the effect of a self-cutting blade implant design on the primary stability of tapered dental implants in a simulated low-density bone model. Implant fixtures with 2 different designs, one with self-cutting blades and the other without self-cutting blades, were fabricated in the same implant system. Insertion torque, resonance frequency analysis, reverse torque, and pull-out and push-in tests were evaluated in grade no. 10 solid rigid polyurethane foam. All 5 assessments of the group without self-cutting blades were significantly higher than those of the self-cutting group (P < .001). The implants without self-cutting blades create a lateral compression with increased contact surface area and consequently improve the primary stability in a simulated low-density bone model.
Article
The aim of this biomechanical study was to assess the influence of self-tapping blades in terms of primary implant stability between implants with self-tapping blades and implants without self-tapping blades using five different analytic methods, especially in medium-density bone. Two different types of dental implants (4 × 10 mm) were tested: self-tapping and non-self-tapping. The fixture design including thread profiles was exactly the same between the two groups; the only difference was the presence of cutting blades on one half of the apical portion of the implant body. Solid rigid polyurethane blocks with corresponding densities were selected to simulate medium-density bone. Five mechanical assessments (insertion torque, resonance frequency analysis [RFA], reverse torque, pull-out and push in test) were performed for primary stability. Implants without self-tapping blades showed significantly higher values (P<0.001) in four biomechanical assessments, except RFA (P=0.684). However, a statistically significant correlation could not be detected between insertion torque values with the four different outcome variables (P>0.05). The outcomes of the present study indicate that the implant body design without self-tapping blades has a good primary stability compared with that with self-tapping blades in medium-density bone. Considering the RFA, a distinct layer of cortical bone on marginal bone will yield implant stability quotient values similar to those in medium-bone density when implants have the same diameter.