IMPLICATION OF NEW IMPLANT SYSTEMS
FOR COMPLEX TREATMENT OF PATIENTS WITH
MAXILLOFACIAL DEFECTS
V.N.Antsiferov 1, G.I.Rogozhnikov 2, N.B.Astashina 2
1
Scientific Center of Powder Material Science of SEIHPI «Perm state technical
university», Perm, Russia
2
SEIHPI «Perm state medical academy n.a. ac. Е.А. Vagner» MHRF, Perm, Russia
Abstract
At the moment the problem of searching new methods for the treatment of the
patients with maxillary bone defects caused by traumatic injuries of maxillofacial area
is to be of current interest. Therefore the group of authors developed new implant
systems made of biologically inert materials with the application of advanced
technologies: compound dentalalveolar implant and the implant with ferromagnetic.
The usage of proposed structures will allow to raise the quality of complex treatment
for patients with maxillofacial defects.
At the moment the problematic treatment of patients with maxillary bone defects
is to be of current interest. In the recent years the number of patients with traumatic
injuries of maxillofacial area cased by majour and local armed conflicts, terroristic
acts, technogenic accidents and catastrophes. Multiple and multisystem injuries of
maxillofacial area are found with 18 % of the total number of trauma patients. The
injuries of facial skeleton, gunshot wounds cause defects and distortions both for bone
tissues and soft tissues of face.
A great number of recent researches indicate extreme difficulties in providing
specialized medical treatment for the patients with maxillofacial tissue injuries.
Therefore new implant systems made of biomaterials for surgical substitution of
submaxilla defect and also performing rational maxillofacial prosthetics afterwards
will help to regain patients’ total ability to work and have social functions which
seemed to be lost.
The urgency of the issue is in choosing the most adapted material to replace
bone defects of maxillary and eliminate maxillofacial area distortions. In order to
restore a missing maxilla part there used both auto-, alloplastic and implant materials.
However apart from the positive characteristics the stated substances might also have
strong disadvantages, in particular, the retrieval of autotransplant might also cause
extra injury of a patient. Automaterials do not always provide the possibility to fully
restore anatomy shape of maxilla. The allotransplantation method is not able to solve
the stated problem due to the fact that there is no available bank of cadaveric tissues,
moreover, there is a big issue of tissue incompatibility. The creation of allotransplants
bone banks is recently limited because of HIV infection and hepatitis B,C.
Today there is great interest in using implants from various materials for
endoprosthesis replacement (metals, ceramics, and composites). Various metal alloys
(aluminum, nickel, nickelic titanium etc) are being used for the purpose of enthesis. It
is determined that the stated metals have a range of essential disadvantages: formation
of microdefects and cracking, metalloz and corrosion, insufficient plasticity. When
using metal structures there might occur tissue reaction against external temperature
1
influence. All the above mentioned facts sufficiently diminishe its dental implant
usage.
Implants made of “pure” carbon-based materials have undeniable advantages.
They have high plasticity, biological inertia, non-toxic, non-carcinogenic and
corrosive properties, they are also fatigue loading resistant. Their elasticity modulus is
similar to the elasticity modulus of bones, and electric conductivity is similar to the
body tissue one. Carbon-based materials have low indices of friction wear. Carboncarbon composite material was developed in Russia which was named “Uglecon-M” –
medical carbon. The scientists of Perm state medical academy (Vagner E.A., Denisov
A.C., Kislyh F.I., Rogozhnikov G.I., Letyagina R.A.) researched the properties of this
material and it was introduced into clinical practice. In 1990 “Uglecon-M” was
approved to be used as endoprosthesis replacement material in dentistry. According to
its chemical composition it is practically “pure” carbon and represents the
composition of carbon fiber and pyrocarbon. The following material is valuable for
the opportunity to provide prosthetic repairs of all native bone parameters, including
architectonics and elastic modulus value. Further improvements and usage of this
material for implant constructions of maxillary bones have determined the urgency of
the issue.
At the moment there is great concern about orthopedic rehabilitation of patients
with maxillofacial area defects. The orthopedic rehabilitation success of patients
depends on bone tissue defect scope and distribution. A tooth which borders on the
defect often misses alveole wall from the side of resection, such teeth are normally
floating. A thick layer of cicatrical-transformed floating of mucous coat is often
developed at the regenerated area which leads to balancing and ejection of removable
denture. The stabilization of orthopedic construction is nearly impossible in case
transplant area has a direct transition of cheeks and lips mucus membrane into the
floor of the mouth or the sublingual swab is located above the regenerate level. The
essential defect value, reduced prosthesis area, floating side tissues, masticatory and
facial muscles tonus make it hard to select the orthopedic treatment method for the
patients with maxillary defects.
The performed researches had a purpose to develop the program of complex
treatment for patients with maxillary defects using biologically inert structural
materials and advanced technologies.
Therefore new implant systems are developed from biologically inert materials with
the application of nanotechnologies – combined carbon-titanium dentoalveolar
implant and carbon implant with ferromagnetic for magnetic fixation of removable
dentoalveolar dentures.
Combined carbon-titanium dentoalveolar implant (fig. 1) has two parts: maxilla
part made of carbon-based material “Uglecon-M” (fig. 1a) which helps to fully
replace maxilla defect; and dental part (fig 1b) made of titanium alloy which acts as
support to fix the following orthopedic construction. When choosing biologically inert
structural materials to build up the dental part of the dentoalveolar implant we focused
our attention on titanium alloy with alpha structure ВТ-5Л, which is one of most
producible ones. Its corrosion resistance in mouth cavities complies with precious
metals, its elastic modulus is similar to bones.
Dentoalveolar implant is produced in the following way: there is a hole made in
the maxillary carbon implant where a titanium dental implant is fixed. The latter
consists of a barrel produced from sintered powder titanium of ВТ-5Л grade and an
auxiliary bar with suprastructure made from solid titanium alloy by milling. Therefore
when working out the stated system, porous and nonporous components were build
2
up. To create strong connection between the construction elements titanium powder is
used (an average diameter of particles is 50 micron) introduced into dental and
maxilla implant clearance. When working there were applied the methods of
nanostructures synthesis with the fixed shape and size to produce implants with
improved, stable biocompatible, physical and mechanical properties. The adhesion
strength of titanium dental implant with carbon material was provided with the help of
sintering of the assembled construction in the vacuum furnace at 1280 ° C within 3
hours due to the creation of the hardened layer between titanium and carbon implants.
For the adhesion quality examination of titanium dental part with carbon maxilla
implant mechanical tests were performed at the tensile-testing machine Hekkert HP
100/1 with the measurement range of 0,4 kN. The contact area of titanium auxiliary
bar with maxillary part was calculated according to the following formula:
S =   r 2  h  r  ,
r – titanium auxiliary bar diameter; h – the height of generatrix cylindrical contact
surface between auxiliary bar and carbon material “Uglekon-M”.
The experiment results showed that the adhesion strength between titanium auxiliary
bar and the carbon maxilla part was 7,6 MPa which is some higher than the adhesion
strength of carbon composition material “Uglekon-M”.
а
b
c
Fig.1. Combined carbon-titanium implant: a) maxilla implant; b) dental implant;
c) produced carbon-titanium implant.
The incorporation of titanium part into the carbon composite material helped to
create a brand new dentoalveolar implant with the positive effect of raising the
treatment effectiveness due to preventive measures for after surgical complications,
good fixation and stabilization of follow-up dentoalveolar prosthesis, availability and
biologically inert properties of the materials used, it is also free from immunologic
havoc when the material is being introduced in the body, consequently it has no
necessity to pull it out. There is an option to produce tailor-made implants. The
identified substitution constructions are easy to be sterilized and fit.
One of the perspective approaches to the problem of complex maxillofacial prosthesis
attachment is using continuous magnetic field. The applied public health service
implemented magnetic unit struction with titanium coating to fix movable
3
dentoalveolar prosthesis which was developed by the group of authors. In the
suggested structure the ferromagnetic component is introduced into the root of the
tooth which limits the defect. However not all the clinical settings have all the notified
conditions.
In this respect an implantation system was developed which consists of carbon
implant with ferromagnetic for magnetic fixation of movable dentalalveolar prosthesis
(fig.2.).
Fig.2. Carbon maxilla implant with introduced ferromagnetic (horizontally cut).
The offered appliance (fig.3.) has maxilla implant (4), made of carbon material
“Uglekon-M” and an inside fixed ferromagnetic component (5). The adhesion
strength of ferromagnetic and carbon material is provided by sintering the assembled
structure in the vacuum furnace at the temperature up to 1100 °C. The structure (fig.4)
provides the usage of movable dentoalveolar prosthesis (1), with the samarium-cobalt
magnetic elements introduced into the artificial teeth of prosthesis (2) with magnetic
circuit made from ferromagnetic (3), through which the magnetic circuit is closed.
Between maxilla implant (4) and the denture bases of movable prosthesis (1) there is
mucous membrane (6). The magnetic element (2) has a cylinder shape and can be
located in any magnetic circuit area (3). To improve biological characteristics and
strength properties the samarium-cobalt magnet and ferromagnetic component are
coated with titanium alloy ВТ1-00 with ion-plasma sputtering method.
The magnetic field lines in the offered structure are directed along the closed
circuit inside the magnetic element and ferromagnetic part.
1
2
3
5
x
6
d
4
Fig. 3. Magnet lock model: 1 – dentoalveolar prosthesis; 2 - samarium-cobalt magnet;
3 – magnetic circuit; 4- dental implant; 5 – ferromagnetic; 6 – mucous coat.
Russian and foreign scientific articles describe analogues of suggested combined
implants in the form of maxilla carbon implants without entering the dental part. The
4
disadvantages of such implants is that during orthopedic treatment after using it there
is no regular ability to create favourable conditions for further prosthetic repairs. The
fact that there is dental part in the offered implant systems provides the full-scale
maxilla defect replacement and the incorporation of dental or ferromagnetic
components allows to create an additional fixation area for further orthopedic
structure.
To research the reaction of bone tissue on the implants incorporation of the
introduced structure (fig. 4 a,b) there was used an experimental group of 10 male pigs
of “Landras” breed, weight from 17 to 18.5 kg, age 52-55 days. The tested animals
(fig. 5a) had their formed segmental defects of submaxilla incorporated with the
proposed implant constructions (fig. 5 b,c).
b
а
Fig.4. Implants, prepared for replacement of bone tissue defect: a) combined
dentalalveolar implant; b) carbon maxilla implant with ferromagnetic.
а
c
b
Fig. 5. Experiment description: a) there was a segmental defect made in the
submaxilla of the tested animal; b) combined dentalalveolar implant was
incorporated; c) carbon maxilla implant with ferromagnetic was fixed.
The results estimation of osteoplasty was performed on bases of clinical
observation data, tissue reaction of the host bed after 1, 5, 10, 20, 30, 90, 150 days.
5
After 6 months the tested animals were taken out of the experiment. When analyzing
the experimental results it was defined that the visual examination of the host bed
status after 6 months of the experiment launch, there was no delay in the operated
submaxilla growth in comparison with the sound part. All the implants tightly adhered
the bone, the soft tissue surrounding the implant were not changed. After the tested
animals were taken out of the experiment when estimating the macromedications (fig.
6), traced with formaline solution there was stated an adherence of proposed
structures with bone tissue. The incorporated dental and ferromagnetic components
were sustainably adhered with maxilla parts of the implant systems.
Fig.6. Macromedication (after 6 months of the experiment launch): The implant is
fixed to the bone issue.
In the structure of the implant-bone block boundary (fig.7.) there were found
reparative regeneration processes of the damaged bone tissue.
1
2
3
4
Fig.7. The structure of the implant-bone block boundary: The impant (1) between
collagen fibers (2); bone tissue bars (3); vessels (4). Van Gieson’s stain, zoom X400.
Vast areas of disorderly arranged collagen fibers which “grow through” (stitch)
the implant were defined at the boundary area of “implant-bone tissue” (fig.8). They
are surrounded by thick vascular bed of great vessels.
6
3
1
2
Fig. 8. The boundary area of “implant-bone tissue”: Implant (1) between collagen
fibers (2); vessels (3). Van Gieson’s stain, ampl. X400.
Good vascular supply on the boundary area of “implant-bone tissue” (fig.9)
provides the differentiation of osteogenic cells in osteoblast which is considered to be
one of the most important terms in osseogenesis.
1
3
2
Pic. 9. The boundary of “implant-bone tissue” area: Collagen fibers growth (1);
vessels (2); Newly formed trabecula of bone (3). Van Gieson’s stain, ampl. X400.
Due to these a non-mineralized osteoid is formed. Collagen fibers get saturated
with osteoid which leads to the formation of trabeculas of bone from coarse-fibered
bone tissue (fig.10). Osteoblasts are located on the edge of trabeculas of bone. High
content of osteocytes is identified in trabeculas of bone (the content of those in
lamellar tissue is lower). Lacunae with osteocytes cells do not have regular
orientation. The observed regenerative processes in the destruction area will further
allow replacement of coarse-fibered bone tissue by lamellar bone tissue of maxilla.
7
2
1
3
3
Рис. 10. Trabeculas of coarse-fibered bone tissue: Vessel (1); collagen fibers (2);
osteocytes (3). Van Gieson’s stain, ampl. X400.
Results of the experiments conducted to define strength characteristics of the
offered systems and study the reactions of bone tissue when implanting, allow to
conclude that it is possible to use them during complex treating the patients with
submaxilla defects.
Positive effect from the application of developed structural systems results in the
increase of the treatment efficiency due to the preventive care of postoperative
complications, biocompatibility of the materials, possibilities to produce tailor-made
implants, shortening treatment period, absence of necessity to remove the implant,
good fixation of dentoalveolar prosthesis. All the abovementioned advantages
provide improvement of health and health-related quality of life for patients.
The article is being published with the financial support of RFFI grant, project
№090899128 “Development of biologically inert composite materials for
development of complex implant systems within the program of complex
rehabilitation of patients with submaxilla defects”.
8