Revisión bibliográfica en implantología

This case report describes the prosthetic rehabilitation of a 73-year-old woman with a longstanding distal edentulous ridge and horizontal bone loss in the posterior mandible. The author describes a guided surgery approach using two narrow implants (Dentaurum tioLogic^® TWINFIT) that enables managing complex bone conditions and avoiding critical anatomical structures.

In der dentalen Implantologie ist ein sorgfältiges Abwägen zwischen Ästhetik, Funktion und Stabilität unerlässlich. Die implantologische Behandlung eines Patienten mit einer parodontalen Erkrankung illustriert diese Herausforderung in besonderem Maße. Diese Fälle sind komplex, da sie nicht nur mit ausgeprägten Knochendefekten, sondern auch mit einem erhöhten Periimplantitisrisiko einhergehen.
Folgender Fachbeitrag beschreibt ein Behandlungskonzept zur implantatprothetischen Rehabilitation im Oberkiefer.

Obwohl eine optimale Vorhersagbarkeit bei der implantatprothetischen Rehabilitation wünschenswert ist, kann sie nicht immer garantiert werden. So kann beispielsweise die klinische Situation zum Zeitpunkt der Implantatfreilegung von den ursprünglichen Erwartungen abweichen. Unter solchen Umständen sind prothetische Freiheit und Flexibilität gefragt. Anhand eines Fallbeispiels zeigt der Autor den Abutment-Switch (tioLogic Twinfit Implantat, Dentaurum) zum Zeitpunkt der Implantatfreilegung von einer plattformbasierten (platform) zu einer konischen (conical) Implantat-Abutment-Verbindung.

In this clinical case study, Dr. Christian Adler M.Sc and dental technician master Jens Neubarth give a step-by-step overview of how to produce an in-house surgical (implantology) guide in a rehabilitation case with partial edentulism by using CAD/CAM technology.

Background
Numerous clinical variables may influence early marginal bone loss (EMBL), including surgical, prosthetic and host-related factors. Among them, bone crest width plays a crucial role: an adequate peri-implant bone envelope has a protective effect against the influence of the aforementioned factors on marginal bone stability. The aim of the present study was to investigate the influence of buccal and palatal bone thickness at the time of implant placement on EMBL during the submerged healing period.

Methods
Patients presenting a single edentulism in the upper premolar area and requiring implant-supported rehabilitation were enrolled following inclusion and exclusion criteria. Internal connection implants (Twinfit, Dentaurum, Ispringen, Germany) were inserted after piezoelectric implant site preparation. Mid-facial and mid-palatal thickness and height of the peri-implant bone were measured immediately after implant placement (T0) with a periodontal probe and recorded to the nearest 0.5 mm. After 3 months of submerged healing (T1), implants were uncovered and measurements were repeated with the same protocol. Kruskal-Wallis test for independent samples was used to compare bone changes from T0 to T1. Multivariate linear regression models were built to assess the influence of different variables on buccal and palatal EMBL.

Results
Ninety patients (50 females, 40 males, mean age 42.9 ± 15.1 years), treated with the insertion of 90 implants in maxillary premolar area, were included in the final analysis. Mean buccal and palatal bone thickness at T0 were 2.42 ± 0.64 mm and 1.31 ± 0.38 mm, respectively. Mean buccal and palatal bone thickness at T1 were 1.92 ± 0.71 mm and 0.87 ± 0.49 mm, respectively. Changes in both buccal and palatal thickness from T0 to T1 resulted statistically significant (p = 0.000). Changes in vertical bone levels from T0 to T1 resulted not significant both on buccal (mean vertical resorption 0.04 ± 0.14 mm; p = 0.479) and palatal side (mean vertical resorption 0.03 ± 0.11 mm; p = 0.737). Multivariate linear regression analysis showed a significant negative correlation between vertical bone resorption and bone thickness at T0 on both buccal and palatal side.

Einleitung und Ziel:
Enossale Implantate bestehen aus einem Implantatkörper, einem Aufbau und der Halteschraube.
Für den Erfolg eines Implantats ist neben der Stabilität auch die Dichtigkeit der Implantat/
Aufbau-Verbindung wichtig. Im Falle einer Undichtigkeit besteht die Gefahr, dass Mikroorganismen
eindringen und das Implantat sowie das Implantatbett kontaminieren, was zu
Periimplantitis mit Knochen- und Weichgewebsverlusten führen kann. Ziel dieser Untersuchung
war, die Dichtigkeit unter mechanischer Dauerbelastung der Implantat/Abutment-Schnittstelle
von Konusverbindungen zu vergleichen. Dabei wurde ein Implantat-System in den Vergleich
einbezogen, das sowohl eine Konus-, als auch eine Plattformverbindung erlaubt.

Material und Methoden:
Die untersuchten Implantat/Abutment-Systeme sind in der unten stehenden Tabelle gelistet.
Die Kriterien für die Dauerlastprüfung von Implantaten sind in der internationalen Norm ISO
14801:2016.1 festgelegt. Diese Norm wurde für den Versuchsaufbau angewandt und für die
Dichtigkeitsprüfung erweitert. Es wurden jeweils 3 Proben in einer Dauerlastprüfmaschine DynaMess
TP 5kN dynamisch belastet.
Für die Dichtigkeitsprüfung wurde eine spezielle Apparatur entwickelt. Eine Mikropumpe wurde
über einen Silikonschlauch mit einer Injektionsnadel verbunden, die in das apikale Ende der Implantate
eingeführt wurde. Nach Einbetten der Implantate in Kunststoff und Einbau derselben in
die DynaMess wurde eine Schwelllastprüfung im Wasserbad über 100.000 Zyklen bei 100 N mit
einer Frequenz von 2 Hz durchgeführt. Nach Abschluss wurde die Pumpe mit einem Druck von
500 mBar eingeschaltet und es folgte eine Dichtigkeitsprüfung über weitere 1.000 Zyklen. Falls
kein gefärbtes Wasser aus der Implantat-/Abutment-Schnittstelle austrat, wurde die Pumpe abgeschaltet,
die Kraft um 50 N erhöht und es folgten weitere 100.000 Zyklen mit nachfolgender
Dichtigkeitsprüfung. Dies wurde so lange wiederholt, bis entweder ein Versagen durch Bruch
oder eine Leckage auftraten.

Ergebnisse:
Die Versagensmechanismen der untersuchten Systeme waren Implantatbruch oder Bruch des
Abutments und Leckagen am Interface. Alle untersuchten Systeme erreichten ein mittleres dynamisches
Belastungsniveau von größer 300 N. Die konischen Systeme zeigten Versagen durch
Bruch des Implantats bei einer mittleren Last von 330 N (Astra) bzw. 630 N (Conelog) und ein
Versagen durch Bruch des Abutments bei einer mittleren Last von 580 N (TWINFIT).
Bei der TWINFIT-Plattformverbindung als Referenzsystem zeigte sich im Mittel bei 320 N eine
Leckage ohne Bruchereignis.

Schlussfolgerungen:
Bei den konischen Systemen ist ein Bruch des Implantats oder Abutments zu erwarten, bevor
eine Undichtigkeit auftritt. Somit kann für alle untersuchten Konussysteme festgestellt werden,
dass die Dichtigkeit im klinischen Bereich gewährleistet ist.

Purpose:
To evaluate the effect of different degrees of mesial implant inclinations on the retention and
stability of two-implant mandibular overdentures retained with stud attachments.

Materials and Methods:
Four experimental mandibular acrylic models were constructed. Two laboratory implants
were inserted in the canine areas of each model with the following degrees of mesial
inclinations: 0, 5, 10, and 20 degrees. Experimental overdentures were connected
to the implants with Locator extra-light retention (Le), Locator light retention (Li), and
Locator medium retention (Lm). Vertical (retention) and oblique (stability) dislodging
forces (anterior, posterior, and lateral) were measured at the beginning of the study
(initial retention) and after 540 cycles of denture insertion and removal (final retention).

Results:
The final retention was not signifi cantly affected by small (5 degrees) and large
(20 degrees) implant inclinations, but decreased with a moderate (10 degrees) inclination.
For a small implant inclination (5 degrees), Lm shows the highest fi nal retention/stability
an Le showed the lowest, while for moderate and large inclinations (10 and 20 degrees),
Le showed the highest fi nal retention/stability and Lm showed the lowest. Vertical dislodging
recorded the highest fi nal stability, and lateral dislodgment recorded the lowest
stability.

Conclusion:
Within the limitations of this in vitro study, only moderate implant angulation (10 degrees)
negatively affects the final retention and stability of Locator-retained overdentures. Locator
medium retention for small angulation (5 degrees) and Locator extra-light retention for
moderate (10 degrees) and large (20 degrees) angulations are recommended to maintain
high retention and stability after 540 cycles of denture insertion and removal.

Purpose:
To evaluate the effect of distal implant inclination on axial and nonaxial retentive forces of
different Locator attachments used to retain mandibular overdentures.

Materials and Methods:
Four duplicate mandibular edentulous acrylic models received 2 implants in the canine areas
with 0°, 5°, 10°, and 20° distal inclinations. Experimental overdentures were connected to
the implants with Locator extra light retention (Le), Locator light retention (Ll), and Locator
medium retention (Lm). For the 20° model, extended range Locator extra-light retention (Lee)
and Locator medium retention (Lem) were used. Axial and nonaxial (anterior, posterior, lateral)
retentive forces were measured initially and after 540 cycles of denture insertion and removal.
Three-way mixed ANOVA was used to analyze axial and nonaxial retentive forces.

Results:
After wear simulation, 20° angulation showed the highest axial retention for Le and Ll
while 5° showed the highest retention for Lm; 0° and 5° showed the highest anterior and
posterior retention for Lm; 20° showed the highest lateral retention for Le and Ll. For all
implant inclinations, Lm showed the highest axial and nonaxial retention, and Le and Lee
showed the lowest retention for 10° and 20° inclined implants, respectively.

Conclusion:
Axial and nonaxial retention of Locator attachments for implantretained overdentures are
signifi cantly affected by the degree of distal implant inclination and the type of nylon inserts.
Lm is recommended to retain overdentures when implants have 5° or 10° distal inclination,
and Le and Ll are recommended with 20° inclination to maintain high axial and nonaxial
retention after wear.

This study aimed to evaluate the periimplant strain around mesially inclined implants used to
retain mandibular overdentures with Locator resilient attachments. Four mandibular edentulous
acrylic resin models received two implants in the canine areas with 0°, 5°, 10°, and 20° mesial
inclinations.

Overdentures were connected to the implants using Locator attachments. Pink nylon inserts
(light retention) were used for all implant inclinations, and red inserts were used for 20° inclination
(20°red). Four strain gages were bonded on the mesial (M), distal (D), buccal (B), and lingual
(L) surfaces of each implant. Peri-implant strains were measured during bilateral and unilateral
loading. The 20° inclination showed the highest strain, followed by 10° and 5°, and both 0° and
20°red presented with the lowest strain. Site D was associated with the highest strain, followed
by M, B, and L, which showed the lowest strain values. Unilateral loading and the loading side
presented with signifi cantly higher strain values than bilateral loading and the nonloading side,
respectively. Hence, in this study, strains around the two-implant-retained overdentures with
Locator attachments increased with increases in mesial implant angulation, except when red
male inserts were used.

Purpose:
This study aimed to evaluate the effect of buccal implant inclination on stresses around
two-implant–retained overdentures with resilient stud attachments.

Materials and Methods:
Four acrylic models representing a mandibular edentulous ridge were constructed. For each
model, two implants were placed at canine areas. Models were classified into four types
according to the degree of buccal implant inclination: Group I (GI, 0 degrees), Group II
(GII, 10 degrees), Group III (GIII, 20 degrees), and Group IV (GIV, 30 degrees). Overdentures
were connected to the implants with Locator attachments. Regular light-retention inserts were
used for all groups, and extended range inserts were also used for GIV (GIVext), making a fifth
comparison group. Four strain gauges were bonded at the buccal, lingual, mesial, and
distal surfaces of each implant to monitor the stresses during bilateral and unilateral
load application.

Results:
Tensile stresses were recorded at distal and lingual gauges, and compressive stresses
were recorded at mesial and buccal gauges for all groups. GIV recorded the highest
stresses, followed by GIII, GII, GIVext, and GI. Distal position recorded the highest stresses,
followed by lingual, mesial, and buccal. Nonloading side was associated with significantly
higher stresses than loading side.

Conclusion:
The peri-implant stresses increase as the buccal implant inclination increases when resilient
stud attachments are used for implant overdentures. Therefore, it is recommended to insert
the implants parallel to each other to decrease peri-implant stresses. However, when buccal
inclination is inevitable due to anatomical limitations, it should be limited to 10 degrees for
standard nylon inserts, or extended range inserts are recommended.

Purpose:
The aim of this study was to evaluate and compare the clinical and radiographic outcomes
of two implants placed in expanded mandibular knife-edge ridge and implants placed in
unexpanded ridges to retain overdentures.

Materials and Methods:
Fifteen completely edentulous patients with knife-edge ridges at canine areas of the mandible
received two implants using the ridge expansion technique (study group, SG). Expansion was
performed using piezoelectric corticotomy, and self-threading expanders. The control group
(CG) comprised patients who received two-implant at canine areas without ridge expansion
but were all case matched to SG and served as historical cohort. In both groups, mandibular
overdentures were connected to the implants with Locator attachments 3 months after implant
placement. Clinical (Plaque index; PI, Gingival index; GI, Probing depth; PD, and implant
stability; ISQ) and radiographic (Vertical bone loss; VBL) parameters were recorded at time of
overdenture insertion (base line, T0), 6 months (T6), and 12 months (T12) after insertion.

Results:
The cumulative success rates were 100 % and 96.4 % for CG and SG, respectively, without
significant difference between groups. All tested parameters increased significantly with
advance of time in both groups. There was no significant difference in PI, GI, PD, and ISQ
between groups. However, SG recorded significant higher VBL than CG at T6 and T12.

Conclusion:
Expansion of mandibular knife edge ridge and simultaneous placement of implants to retain
overdentures is associated with clinic and radiographic outcomes comparable to implants
placed in unexpanded ridges after 1 year. However, long term randomized controlled trials
with sufficient sample size are still needed to ensure the findings of the present study.

Purpose:
The aim of this study was to evaluate and compare strain around abutment teeth with different
attachments used for implant-assisted distal extension partial overdentures (IADEPODs).

Materials and Methods:
A mandibular Kennedy class I acrylic model (remaining teeth from fi rst premolar to fi rst
premolar) was constructed. A conventional partial denture was constructed over the model
(control, group 1). Two laboratory implants were then placed bilaterally in the fi rst molar areas
parallel to each other and perpendicular to the residual ridge. Three additional experimental
partial overdentures (PODs) were constructed and connected to the implants using ball
(group 2), magnetic (group 3), and Locator (group 4) attachments. Three linear strain gauges
were bonded buccal, lingual, and distal to the fi rst premolar abutment tooth at the right
(loading) and the left (nonloading) sides. For each group, a universal testing device was used
to apply a unilateral vertical static load (50 N) on the fi rst molar area, and the strain was
recorded using a multichannel digital strainometer.

Results:
Signifi cant differences between groups and between sites of strain gauges were detected.
Strains recorded for all groups were compressive (negative) in nature. Group 1 demonstrated
the highest strain, followed by group 3 and group 4; group 2 recorded the lowest strain. For
group 2, the highest strain was recorded at the lingual nonloading side. For group 1, group 3,
and group 4, the highest strain was recorded at the buccal loading side.

Conclusion:
Within the limitation of the present study, ball attachments used to retain IADEPODs to
the implants were associated with lower strains around abutment teeth than Locator and
magnetic attachments. The highest strain was recorded with conventional partial dentures.

Purpose:
The aim of the present study was to evaluate, by means of strain gauge analysis, the effect of different implant angulations on strains around two implants retaining mandibular overdenture with Locator attachments.

Materials and Methods:
Four duplicate mandibular acrylic models were constructed. Two implants were inserted in the canine regions using the following degrees of distal inclinations: group I (control); 0o, group II; 10o, group III; 20o, and group IV; 30o. Locator pink attachments were used to connect the overdenture to the implants and Locator red (designed for severely angled implants) was used for group IV (group IVred). For each group, two linear strain gauges were attached at the mesial and distal surfaces of the acrylic resin around each implant. Peri-implant strain was measured on loading and non-loading sides during bilateral and unilateral loading.

Results:
For all groups, the mesial surfaces of the implants at loading and non-loading sides experienced compressive (negative) strains, while the distal implant surfaces showed tensile (positive) strains.Group IV showed the highest strain, followed by group III, group II. Both group I and group IV red showed the lowest strain. The strain gauges at the mesial surface of the loading side recorded the highest strain, and the distal surface at non-loading side showed the lowest strain. Unilateral loading recorded signifi cantly higher strain than bilateral loading.

Conclusion:
Peri-implant strains around two implants used to retain mandibular overdentures with Locator attachments increase as distal implant inclination increases, except when red nylon inserts were used.

This study aimed to evaluate peri-implant tissue health of immediate loaded two implants
retaining a mandibular overdenture with either magnetic or locator attachment. Thirty two
completely edentulous patients (20 males / 12 females) were randomly assigned into two groups.
Each patient received two implants in the canine area of the mandible using flapless surgical
technique. Mandibular overdentures were immediately connected to the implants with either
magnetic (group I, GI) or locator (group II, GII) attachments. Peri-implant tissue health was evaluated
clinically in terms of plaque scores (PI), bleeding scores (BI), probing depth (PD), implant
stability (ISQ) and interleukin-1-b (IL-1b) concentrations in periimplant sulcular fluid. PI, BI and
PD were measured at mesial, distal, buccal and lingual surfaces of each implant. Radiographic
evaluation was performed in terms of vertical (VBL) and horizontal (HBLO) alveolar bone loss.
Evaluations were performed 2 weeks (T0), 6 months (T1) and 12 months (T2) after overdenture
insertion. Plague scores, PD, IL-1b, VBL and HBLO increased significantly with time. ISQ
decreased significantly with time. BI showed no significant differences between observation
times. GI recorded significant higher PI, ISQ and IL-1b at T2 compared to GII. GII recorded significant
higher VBL than GI at T2 only. For HBLO, no significant differences between groups were
noted. VBL and HBLO showed a significant positive correlation with PD. Locator attachments for
immediate loaded implants retaining mandibular overdentures are associated with decreased
plaque accumulation, decreased implant stability, decreased interleukin-1b concentration in
peri-implant crevicular fluid and increased perimplant vertical bone loss compared to magnetic
attachments after 1 year.

Purpose:
The aim of this study was to evaluate and compare the retention and stability of mandibular
implant overdentures using different types of resilient attachments.

Materials and Methods:
Two implant analogs were inserted in the canine areas of an acrylic edentulous mandibular
model. A metal-reinforced experimental overdenture was constructed and connected to the
implant analogs (on two occasions) using either resilient telescopic or Locator attachments.
Locators were divided into three subgroups according to the degree of retention of the male
nylon insert: Locator extra-light retention (blue insert), Locator light retention (pink insert), and
Locator medium retention (transparent insert). Vertical and oblique (anterior, posterior,
and lateral) dislodging forces were measured at the beginning of the study (initial retention)
and after 540 cycles of denture insertion and removal (final retention).

Results:
For all dislodging forces, Locator medium recorded the highest initial and final retention.
Telescopic attachments recorded the lowest retention during vertical and anterior dislodging,
and Locator extra-light recorded the lowest retention during lateral and posterior
dislodging. For all types of Locator attachments, anterior dislodging recorded the highest
initial and final retention, and lateral dislodging recorded the lowest retention. For the
telescopic attachment, posterior dislodgment recorded the highest initial retention, and
anterior dislodging recorded the lowest retention.

Conclusion:
After repeated denture insertions and removals, the highest retention and stability were
recorded with Locator medium followed by Locator light. The lowest retention was recorded
with resilient telescopic attachment, and the lowest stability was recorded with Locator
extra-light.

Purpose:
To evaluate and compare retentive properties of O-ring and Locator attachments for
implant-retained maxillary overdentures.

Materials and Methods:
Four implant analogs were inserted in canine and second premolar areas of an acrylic
edentulous maxillary model. A metal-reinforced experimental acrylic overdenture was constructed
and connected to the analogs using either O-ring (group I) or Locator (group II)
attachments. Locators were divided into 3 subgroups according the degree of retention of the
patrix nylon insert: Locator extralight retention (group IIa), Locator light retention (group IIb),
and Locator medium retention (group IIc). Vertical and oblique (lateral, anterior, and posterior)
dislodging forces were measured at the beginning of the study (initial retention) and after 540
cycles of denture insertion and removal (final retention).

Results:
For vertical, lateral, and anterior dislodging, group IIc recorded the highest initial and
final retention, and group I recorded the lowest retention. For posterior dislodging,
group I recorded the highest retention, and group IIa recorded the lowest retention. For
group II, vertical dislodging recorded the highest initial and final retention, and lateral
dislodging recorded the lowest retention. For group I, posterior dislodging recorded the
highest initial and final retention, and lateral dislodging recorded the lowest retention. For
all dislodging forces (except posterior dislodging), the highest retention loss was recorded
in group I, and the lowest retention loss was recorded in group IIa.

Conclusion:
Locator medium attachment was associated with favorable retention during axial (vertical)
and nonaxial (anterior and lateral) dislodging compared to other types of Locator inserts and
O-ring attachments after a simulated 6-month period of overdenture use.

This study evaluated the effect of implant diameter on strain around implants retaining
mandibular overdentures with Locator attachments. Three mandibular acrylic resin models were
constructed with 2 implants inserted in canine areas and classified according to implant diameter
into 3 groups: large (4.2 mm), medium (3.7 mm), and small (3.3 mm) diameter implants.
Duplicate dentures were connected to the implants with Locator attachments. Four strain
gauges were bonded to the acrylic resin at mesial, distal, buccal and lingual surfaces of each
implant and strain was measured at loading and non-loading sides during 1st premolar and
1st molar loading. Small and large diameter implants recorded the highest and the lowest
strain, respectively. Buccal and lingual sites recorded the highest strain, and mesial site recorded
the lowest. First premolar loading recorded significant higher strain than first molar loading.
The largest possible implant diameter is recommended to minimize strains around implants
retaining mandibular overdentures with Locator attachments.

Purpose:
The aim of this in vitro study was to evaluate and compare mandibular denture base
deformation between ball and Locator attachments of implant-retained overdentures.

Materials and Methods:
An experimental acrylic model covered with resilient silicone mucosal simulation was
constructed. Two laboratory implants were placed in the canine areas of the model. Two
duplicate experimental overdentures were constructed and connected to the implants with
either ball (GI) or Locator (GII) attachments. To measure overdenture strain around the
attachments, 3 strain gauges were attached to the lingual polished surface of the overdentures
opposite to the right implant (loading side) 2 mm above the attachment level (Ch1), at
the attachment level (Ch2), and 2 mm below the attachment level (Ch3). Another 3 gauges
were bonded opposite to the left implant (non-loading side) in the same manner (Ch6, Ch7,
and Ch8). To measure strain at the midline of the overdentures, two strain gauges were
attached in the midline at 5 mm intervals (Ch4 and Ch5). A universal testing device was
used to deliver vertical static load of 50 N unilaterally and bilaterally to the first molar area to
measure strain using a multi-channel digital strain meter.

Results:
During bilateral load application, GII recorded higher compressive strains than GI at the
majority of channels. During unilateral load application, GI recorded higher tensile strains at
Ch1, Ch2, and Ch3, and GII recorded higher strains than GI at Ch6, Ch7, and Ch8. During
bilateral loading the highest strain was concentrated at Ch5 for both groups. During unilateral
loading, the highest strain was concentrated at Ch2 for GI, and at Ch5 for GII.

Conclusion:
Ball attachments for implant-retained overdentures were associated with significant
mandibular denture base deformation over the implants compared to Locator attachments.
Therefore, denture base reinforcement may be recommended with ball attachmentz to
increase fracture resistance of the base.

The aim of this 1-year study was to evaluate and compare crestal bone loss and clinical
outcomes of immediate and delayed loaded implants supporting mandibular overdentures with
Locator attachments. In a randomised controlled clinical trial, 36 completely edentulous patients
(mean age 59.6 years) who desired to improve the stability of their mandibular dentures were
randomly assigned into two groups. Each patient received two implants in the canine area of
the mandible after a minimal flap reflection. Implants were loaded by mandibular overdentures
either 3 months (delayed loading group, G1) or the same day (immediate loading group, G2)
after implant placement. Locator attachments were used to retain all overdentures to the
implants. Peri-implant vertical (VBL) and horizontal (HBLO) bone losses and clinical parameters
[plaque scores (PI), gingival scores (GI), probing depths (PD) and implant stability (ISQ)] were
assessed at time of overdenture insertion (T0), 6 months (T6) and 12 months (T12) after
overdenture insertion. After 12 months of overdenture insertion, two implants (5.5 %) failed
in G2. Vertical bone loss was significantly higher in G2 compared with G1, while HBLO
demonstrated insignificant differences between groups. All clinical parameters (PI, GI, PD and
ISQ) did not differ significantly between groups. Vertical bone loss was significantly correlated
with PD and HBLO. Immediately loaded two implants supporting a Locator-retained mandibular
overdenture are associated with more vertical bone resorption when compared to delayed
loaded implants after 1 year. Clinical outcomes do not differ significantly between
loading protocols.

Reduced vertical bone level in the implantation area is often considered one of the
limiting factors before implant insertion. Inserting implants of reduced length might
be useful in order to avoid vertical bone augmentation prior to implantation. To the
present day, no official guidelines exist as to the optimal length for these implants. It
is nevertheless well known that the stability of an implant depends primarily on its osseointegration,
which could otherwise be influenced by modifying implant surface texture.
The aim of our study was to evaluate osseointegration in correlation with implant length
and surface texture. Three different variations of titan implants (n = 5) were compared:
two types, each with an acid-etched and ceramic blasted surface, were inserted in the
upper jaw of adult female minipigs at different lengths (tioLogic ST Shorty, 5 mm length;
tioLogic© ST, 9 mm length) and were compared to a control group (tioLogic© ST, 9 mm
length, ceramic blasted surface). Eight weeks after unloaded healing, bone tissue specimens
containing the implants were processed, stained with Masson–Goldner-trichrome
and analyzed histologically. Regardless of implant length and surface texture, new bone
formation with no signs of inflammation could be detected in the area of the threads.
Implants with a modified surface showed no statistically significant difference in boneimplant-
contact (BIC) (tioLogic© ST Shorty, 56.5%; tioLogic© ST; 77.2%), but a statistically
significant difference could be found, when the 9 mm implants were compared to
the control group (BIC 48.9%). Surface modification could positively influence osseointegration
as well as contribute to overcoming the adverse effects of length reduction.

Zur Untersuchung der Knochenumbauvorgange sind neben klinischen auch biomechanische
Methoden, die den Hauptgegenstand der vorliegenden Arbeit bilden, von besonderer
Bedeutung. Insbesondere numerische Simulationen der Knochenumbauprozesse können
erheblich zum Erkenntnisgewinn über diese Prozesse beitragen. Die Einheilung von Implantaten
ist entscheidend von diesen Prozessen abhängig. Da bei bisherigen Modellen
die spongiöse Knochenstruktur nur sehr bedingt mit der realen Situation vergleichbar
war, und gerade bei der Etablierung neuer numerischer Methoden auf eine geeignete
Validierung geachtet werden muss, wurde im Rahmen der vorliegenden Arbeit mit
der Finite-Elemente-Methode ein komplett neues computergeneriertes Knochenmodell
vorgestellt, welches nicht mehr nur rechnerisch, sondern auch optisch die realen
Knochenumbauprozesse nachbildet. Die Auslenkung der Implantate und die Knochendichte
sind die Hauptkriterien bei der Validierung der Modelle.

Die experimentelle und numerische Untersuchung des Einheilverhaltens zahlreicher
unterschiedlicher Implantattypen diente dabei als Grundlage für die Untersuchungen und
die Modellgenerierung. Dabei wurden mehrere Finite-Elemente-Modelle für die numerischen
Untersuchungen entwickelt. Diese Modelle umfassten verschiedene Komplexitätsgrade,
angefangen bei idealisierten Knochenmodellen über nachmodellierte Präparate bis hin zu
dem idealisiert-realistischen dreidimensionalen Modell, welches sich im Rahmen der FEMSimulation
zum Knochenumbau bildet. In systematischen Simulationen wurden die numerischen
Modelle zur Implantateinheilung entwickelt, optimiert und mit Hilfe experimentell
ermittelter Daten validiert und so konnte ein vergleichbares Verhalten erzielt werden.

Um auch eine Validierung nicht nur der numerischen, sondern auch der experimentell
gewonnenen Ergebnisse zu ermöglichen, waren auch in-vivo-Experimente erforderlich. Aus
früheren Studien ist bekannt, dass sich Rentiergeweihe für diesen Zweck als Tiermodell
besonders eignen, da sie ein sehr ähnliches physiologisches Verhalten zum menschlichen
Kieferknochen aufweisen.

Hierzu war die Entwicklung eines neuartigen Gerätes zur Simulation der im menschlichen
Kiefer auftretenden Belastungen erforderlich. Der dabei entstandene Kausimulator bringt
diese Belastungen als periodische Intervalle mittels eines Druckstempels auf ein im Rentiergeweih
inseriertes dentales Implantat auf. Sein hochgradig optimierter Stromverbrauch erlaubt
auch langfristige autonome Untersuchungen an frei laufenden Tieren. Die regelmassige
Kontrolle und Rekonfiguration mehrerer zeitgleich eingesetzter Kausimulatoren kann über
direkte Funkverbindung zu einem beliebigen Computer erfolgen. Ein Einfangen der Tiere
ist nur für die Implantation der dentalen Implantate in das Geweih notwendig. Dabei wird
ebenfalls der Kausimulator angebracht und in Betrieb genommen. Der Kausimulator konnte
erfolgreich an zwei Tieren getestet und die gewonnenen Daten ausgewertet werden.

This study sought to evaluate platform-switched implants for immediate placement. A total
of 136 implants were placed in 58 patients using either an immediate or delayed implant
protocol. Bone level changes of the implants were measured mesially and distally and statistically
analyzed with linear mixed models. No implant was lost. There was no significant
difference between immediate and delayed implants in approximal bone level changes during
the first year (95% confidence interval: –0.10 to –0.01 for immediate versus –0.14 to
–0.07 for delayed implants). Subsequent bone resorption was negligible in both groups. (Int
J Periodontics Restorative Dent 2013;33:365–372. doi: 10.11607/prd.1276)

The maximum stresses and strains of the new implants with self-tapping threads were
comparable to values determined in earlier studies. Moreover, the displacements of the new
implants were even smaller than the current implants and the biomechanical properties of
the analysed implants were positively improved by integrating the self-tapping threads.

Aims:
To compare the reaction of the alveolar bone to the preservation of the extraction socket by
Bio- Oss Collagen with and without combination of implant treatment. To evaluate whether
early implant insertion 8–10 weeks thereafter could be a suitable time point for long term
bone stability around the implant.

Methods:
A total of 25 patients were divided into three groups: The first group (seven patients) received
Bio-Oss Collagen after extraction and 8–10 weeks later an implant, the second group
(eight patients) received only Bio-Oss Collagen without implantation thereafter, while the
third group was considered as a control (eleven patients), where the sockets healed without
any treatment. The change in the vertical bone level of the alveolar crests were measured
from panoramic radiographs and statistically analysed.

Results:
Bone level change was significantly less for Group 1 than Group 3 (P < 0.001), while was not
significantly different for Group 2 and Group 3 (P = 0.23). However, the rate of bone level
change per year was statistically smaller for Group 1 compared to Group 3 (P = 0.019) and
as well as for Group 1 than for Group 2 (P = 0.003), whereas the change per year was not
significantly different for Group 2 vs. Group 3 (P = 0.122).

Conclusion:
Bone level preservation of extraction sockets using Bio-Oss Collagen with implantation is
significantly better compared to using Bio-Oss Collagen only and untreated sockets. Implant
insertion 8–10 weeks after extraction is a suitable time point after socket augmentation.

The aim of the present study was to investigate experimentally and numerically the
influence of a fine threaded- against a roughened-cervical region of immediately loaded
dental implants in combination with straight and 20-angled abutments on the implant
primary stability. A total of 30 implants were inserted in bovine rib-segments, 14 cervically
roughened implants and 16 implants with fine cervical threads. Each implant system
received two abutments, straight and 20-angled. Implant displacements and rotations were
measured using a biomechanical measurement system. Subsequently, eight samples were
selected for geometrical reconstruction and numerical investigation of stress and strain
distributions in the bone by means of the finite element method. Experimentally, both
implant systems showed similar behaviour with the straight abutments concerning displacements
and rotations. However, fine threaded implants showed much less displacement and
rotation against roughened implants when angled abutments were considered. Numerically,
stresses were within 35–45 MPa in the cortical bone for both implant systems. The strains
showed highest values within the spongious bone with the roughened implants connected
to angled abutments. The results indicate that implants with fine cervical threads could be
recommended in particular with angled abutments. The outcomes of this study are currently
confirmed by long-term clinical investigations.

To improve osseointegration, different possible dental implant surface modifications, e.g.,
alterations of surface chemistry and roughness, have been developed. The purpose of this
study was to examine the in vitro biocompatibility of newly designed zirconium implants
with different surface modifications in comparison with commercially available zirconium
and titanium implants. Therefore, cell viability and proliferation were measured after
21 days and correlated with surface structures. In the presence of new ceramic implants
with an “mds (blasted/etched)” and a “blasted” surface, cell viability was 1.29- and 1.26-
fold increased, respectively, compared to untreated cells, whereas cell viability was unchanged
in the presence of reference implants and new ceramic implants with an “etched”
surface. The cell viability findings correlate with the results of the cell cytotoxicity assay. The
etched implants showed a surface with high roughness and heterogeneity, whereas the
mds and blasted implants showed a similar, very rough-textured homogenate surface. The
in vitro biocompatibility of two new ceramic implants was significantly better in comparison
with the tested reference ceramic and titanium implants. The good biocompatibility may be
attributed to the homogenous surface of these implants, and these surfaces might hasten
osseointegration.

The effect of bone remodeling on the long-time success of dental implants is becoming critical
for implant design and presurgical assessments. This study applies a previously presented
remodeling simulation scheme on a computer tomography (CT)-based finite element model.
The CT data of a dental implant at the upper right central incisor region 6 years after implant
insertion was used. The time-dependent density change of the trabecular bone after osseointegration
was studied. The trabecular structure, by means of density distribution, around
the implant showed similarities to the CT images at many regions.

In recent years, mini and short dental implants have become increasingly popular as treatment
alternatives for patients in whom the bone is unsuitable for a standard implant. As yet,
no detailed scientific analysis of the mechanical and biomechanical impact of the reduced
diameter and length of these implants has been published. We analysed 21 commercially
available implants (13 mini, eight short) with respect to material behaviour and load transfer
to the alveolar bone, using finite element (FE) analysis. Following μ CT scanning and geometry
reconstruction, FE models of mini implants and short implants were inserted into
idealised bone segments. Mini implants were analysed in the anterior mandibular jaw region
at a force of 150 N under immediate loading, using a contact analysis in the FE software
package Marc Mentat 2007. Short implants were inserted in posterior bone segments and
analysed in the osseointegrated state at an occlusal force of 300 N. Von Mises stresses (up
to 1150 MPa) in mini implants partly exceeded the ultimate strength. Implant diameter and
geometry had a pronounced effect on stresses in the cortical plate (up to 266 MPa). Strains
in spongy bone and stresses in cortical bone around short implants were markedly increased
compared to those in standard implants. An increased risk of bone damage or implant
failure may be assumed in critical clinical situations.