The purpose of this study was to evaluate the survival rate and incidence of prosthetic complications in 377 implants with a double octagon connection. Furthermore, the correlations among implant dimensions (diameter and length), bone quality, and insertion torque were investigated. A 4-year multicenter prospective clinical study was designed to evaluate the survival rate of 377 dental implants inserted in 189 patients between January 2004 and April 2010. After an average follow-up of 46 months, the implant survival rate was 99.7%, and the incidence of complication was 0.53%. Moreover, insertion torque was statistically related in a significant way to implant diameter. The connection system seemed to reduce the risk that the prosthetic component screw would loosen. Within the limits of this study, it was observed that a wider diameter corresponded to a higher implant primary stability. Implant length did not seem to be critical in obtaining higher primary stability.

Introduction

Dental implant/prosthetic rehabilitations are supported by more than 30 years of scientific evidence, which proves that these kinds of procedures are safe and predictable.1  The concept of survival and success rates is of great importance for clinicians in implant dentistry. Survival rate is a liberal assessment related to dental implant mobility as a primary criterion for evaluation. Clinical success rates, however, are more stringent and take into account additional factors, including bone loss, pain, signs of bleeding and inflammation around the peri-implant tissues, and prosthetic complications. Recent long-term studies have reported a success rate of 95% in 668 dental implants supporting fixed partial denture prostheses. The observation period was 6.5 years with a range from 1.5 to 15 years.5  In another study, 1583 implants were observed for a period ranging from 1 to 5 years with a success of 96.5%.3  A survival rate of 98% was described in a sample of 2549 implants followed for 1 to 6 years.24  The efficiency of implant abutment connection is an important factor for clinical success.5 

The biomechanical aspect of a connection is fundamental because it is subjected to micromovements and, consequently, a pumping effect,6  These factors may adversely affect the long-term stability of the peri-implant hard and soft tissues. Connection micromovement is also a risk factor that can lead to the loss of screw preload, thus increasing biological (eg, bacterial infiltration, stress on marginal bone) and biomechanical (eg, screw fracture) risks.7  Internal connections have generally proven to be more reliable from a biomechanical point of view. The purpose of the new connection shape of dental implants is to improve fixture-abutment stability and reduce a prosthetic step.68 

To overcome the antirotation deficiency of the external hexagon, a variety of new connections have evolved. A study8 comparing 3 kinds of connections demonstrated that the internal hexagon and internal octagon offer greater stability of the abutment and a higher resistance to cyclic fatigue than the external hexagon. Studies on external connections suggest they are less efficient than internal conncections.9,10  The advantages offered by internal connections include greater stability and a better response to lateral forces. The highest percentage of prosthetic complications occurs in single-tooth rehabilitations in posterior areas with a high masticatory load.11,12  A meta-analysis13  showed an incidence of connection-related complications of 7.3% after 5 years of prosthetic loading. These data are confirmed in a more recent systematic review,14  where the authors report a 12.7% incidence of screw preload loss and a 0.35% incidence of screw fracture.

It is generally accepted that the diameter and length of an endosseous dental implant and its stability at placement are critical in establishing and maintaining osseointegration. The biomechanical success of a dental implant is related to stress transfer to the surrounding bone. Stress distribution from an implant to the surrounding bone depends on the type of loading, the bone-to-implant contact, the length and diameter of the implants, the shape and characteristics of the implant surface, the prosthesis type, and the quantity and quality of the surrounding bone.15,16  A fundamental aspect that determines the effectiveness of a dental implant is related to the osseointegration process. All of these factors are also influenced by operator experience.1517  Increasing the diameter and length of an implant decreases the stress and strain on the alveolar crest, and the stress and strain values notably increase under masticatory loading compared with vertical loading. However, the diameter of an implant has a more significant effect than length on relieving the bone-level stress and strain concentration.1523 

The main purpose of this 4-year multicenter prospective clinical study was to evaluate the survival of 377 dental implants (Global Sweden & Martina, Padova, Italy) inserted in 189 patients between January 2004 and April 2010 with a mean follow-up of 46 months. Furthermore, the correlations among implant dimensions (diameter and length), bone quality, and insertion torque were investigated.

Materials and Methods

Patient selection

From January 2004 to April 2010, 377 implants were placed in 189 consecutively treated patients. Of these, 187 implants were placed in male patients and 190 in female patients. At the time of implant placement the patients' average age was 51 years, and they were followed for approximately 46 months. The experimental protocol was described to all patients, and they signed an informed consent before undergoing treatment. Patients were told this study was an observational protocol with the aim of evaluating the performance of an implant system already used. Moreover, the surgical and prosthetic procedures the patients would undergo had been previously published in the scientific literature1223 ; thus, no experimental technique would be performed. For this reason the protocol did not require approval by an ethics committee.

This multicenter study included the participation of 10 oral surgeons with varied surgical experience, including faculty members, practitioners, and postgraduate students. All practitioners followed a strict manufacturer's protocol.

Exclusion criteria

The exclusion criteria were insufficient oral hygiene, smoking more than 20 cigarettes per day, alcohol or drug abuse, acute oral infections, untreated metabolic disorders, radiotherapy of the oral maxillofacial region, recent chemotherapy, and pregnancy. To increase the heterogeneity of the sample, consecutive enrollment was followed. The surgical protocols were not subject to any limitations. In the protocol, immediate loading or delayed procedures as well as implants inserted in native bone or associated with guided bone regeneration techniques (29% of patients) were included. All patients received treatment as presented in Tables 1 and 2.

Table 1

Drug dosage that each patient received before and after treatment

Drug dosage that each patient received before and after treatment
Drug dosage that each patient received before and after treatment
Table 2

Clinical and radiographic evaluation of the procedures received by the patient during the treatment

Clinical and radiographic evaluation of the procedures received by the patient during the treatment
Clinical and radiographic evaluation of the procedures received by the patient during the treatment

Dental implant selection

The implant used in the study has a partially cylindrical body at the coronal section with a progressively conical shape at the apex. The variable taper is narrower at the neck and at the first middle section and wider at the apical section. The thread has a conical profile with a pitch of 0.6 mm and depth of 0.4 mm. The outer spire has a progressive profile with an angle of 60°, and it continues to the apex of the implant. Moreover, the implant is characterized by 2 long, apical, spiral, and deep grooves with a rounded apex. In terms of length and diameter, all implant sizes were used as provided by the manufacturer. The most common implant diameter was 5.5 mm, and the most common narrow implant was 3.8 mm. The surfaces of all the implants were sand-blasted, acid-etched, and modified with hydrogen peroxide rinse (ZirTi).22 

The implant connection consists of 2 internal octagons and a terminal collar (Figure 1). The coronal octagon is used during implant placement to apply the necessary torque for implant insertion. The deeper octagon is precision-designed to reduce mechanical stress between the implant and the prosthetic connection, and to provide the smallest degree of tolerance for the prosthetic restoration. The collar functions as a prosthetic guide and allows for a longer connection (3.5 mm in total), thereby improving biomechanical stability. The connection is designed this way in order to house the head of the screw inside the implant neck. In addition, the surfaces between the components are not flat, but formed by 2 spheres that interface according to their concavity, coming into contact along an ideal line that coincides with the diameter of the smaller sphere (Figure 2).

Figures 1 and 2.

Figure 1. Double octagon connection. Figure 2. Radiograph taken 2 years after surgery. Note the correct seating of the prostheses and the absence of fracture lines in the screw or abutment.

Figures 1 and 2.

Figure 1. Double octagon connection. Figure 2. Radiograph taken 2 years after surgery. Note the correct seating of the prostheses and the absence of fracture lines in the screw or abutment.

Preoperative and postoperative instructions

One week before surgery, patients underwent a single session of oral hygiene. All patients were premedicated with an oral antibiotic of amoxicillin and clavulanic acid (Zimox, 1 g cpr, Pfizer Italia Srl, Rome, Italy) 2 hours before surgery, and received an additional 1 g every 8 hours for 6 days. Acetaminophen and codeine (Coefferalgan 500 mg + 30 mg cpr, Bristol-Myers Squibb Srl, New York, NY) was prescribed for postoperative pain control. Patients were also prescribed a chlorhexidine rinse to administer 3 times daily starting 1 week before surgery and continuing until suture removal.

Implant surgery

Surgery involved a full-thickness flap to expose the bone. Osteotomies were created following the manufacturer's protocol, using a sequence of varied diameter drills under saline irrigation. A 2-stage procedure was indicated for the dental implant brand used in the study, and healing screws were placed about 3 or 4 months after the dental implant positioning. The 3/0 silk sutures were removed approximately 1 week after surgery, except in situations that involved bone reconstruction, in which case they were removed at approximately 2 weeks after surgery.

Clinical and radiographic evaluations

Intraoral radiographs were standardized through a parallel beam technique using Rinn centering devices individualized with polyvinyl siloxane occlusal registrations. During surgery, implant length and diameter, insertion torque, and bone quality were recorded. Insertion torque was measured using a dynamometric screw at the moment of insertion and recorded in the patient record. Bone quality ranged between 2 and 3 per the Lekholm and Zarb23  classification. Implant healing, including mobility, was assessed clinically and radiographically at each follow-up visit. The soft tissues were evaluated for the presence of inflammation, bleeding, suppuration, or exudate using a periodontal probe. In addition, bone support was evaluated and proper prosthetic fit confirmed.

One investigator performed a periodontal evaluation using the Periodontal Screening Index (PSI) at 4 proximal sites per implant. All dental implants were probed at 4 sites (mesiovestibular, distovestibular, mesio-oral, and disto-oral) and the PSI score (0 to 4) was recorded. A peri-implant sulcus deeper than 4 mm was considered a pathologic condition based on the Community Periodontal Index of Treatment Needs.24 The following classifications were assigned for each participant in this study: a PSI score of 0, 1, and 2 indicates no periodontitis, and a PSI score of 3 or 4 indicates peri-implantitis.24 

The prostheses were evaluated for stability, fit, screw or abutment fracture lines, and ceramic chips or fractures (Figure 2).

Results

In total, 377 implants were placed: 179 in the maxilla and 198 in the mandible. Of these, 276 implants were placed in the posterior region (distal to the first premolar) and 101 in the anterior (up to the first premolar) (Figure 3).

Figures 3–7.

Figure 3. Histogram position on 377 patients. Figure 4. Pie chart showing distribution of the implant usage according to the prosthetic rehabilitations: 192 implants were inserted to support a fixed bridge (blue area), 156 implants replaced a single tooth that was missing for a minimum of 60 days (green area), 18 implants were placed in postextraction sockets (purple area), 15 implants received a temporary prosthesis after immediate loading protocols (yellow area), and 11 implants were used in full-arch rehabilitation (red area). Figure 5. Pie chart showing bone graft distribution: 5 patients (blue area) were treated with autogenous bone grafts, 21 (green area) using a mixture of autogenous and heterologous bone graft, and 91 (yellow area) using deprotenized bovine bone mineral only, all of them in association with collagen resorbable membranes. Figure 6. Scatterplot showing torque-diameter correlation. (diameter [dp4]: 1 = 3.8 mm; 2 = 4.3 mm; 3 = 4.8 mm; 4 = 5.5 mm). Figure 7. Scatterplot showing correlations between torque and bone quality.

Figures 3–7.

Figure 3. Histogram position on 377 patients. Figure 4. Pie chart showing distribution of the implant usage according to the prosthetic rehabilitations: 192 implants were inserted to support a fixed bridge (blue area), 156 implants replaced a single tooth that was missing for a minimum of 60 days (green area), 18 implants were placed in postextraction sockets (purple area), 15 implants received a temporary prosthesis after immediate loading protocols (yellow area), and 11 implants were used in full-arch rehabilitation (red area). Figure 5. Pie chart showing bone graft distribution: 5 patients (blue area) were treated with autogenous bone grafts, 21 (green area) using a mixture of autogenous and heterologous bone graft, and 91 (yellow area) using deprotenized bovine bone mineral only, all of them in association with collagen resorbable membranes. Figure 6. Scatterplot showing torque-diameter correlation. (diameter [dp4]: 1 = 3.8 mm; 2 = 4.3 mm; 3 = 4.8 mm; 4 = 5.5 mm). Figure 7. Scatterplot showing correlations between torque and bone quality.

The average implant insertion torque was approximately 45 Ncm with a minimum of 10 Ncm and a maximum of 70 Ncm. Sufficient primary stability was achieved in all cases, even in patients with poor bone quality. Of the implants, 3% were mobile to rotation; however, none were mobile when subjected to horizontal or axial forces. All implants achieved osseointegration.

Of the implants, 192 were used to support a fixed bridge and 156 were used to replace single teeth. Furthermore, 18 implants were immediately placed in extraction sockets, 11 implants were used for a full arch rehabilitation, and 15 implants received an immediate load provisional prosthesis (Table 3 and Figure 4).

Table 3

Number and classification of the different surgical and prosthetic restorations

Number and classification of the different surgical and prosthetic restorations
Number and classification of the different surgical and prosthetic restorations

Guided bone regeneration techniques were used in 29% of the patients (117 of 377). Of these 117 patients, 5 were treated by means of autogenous bone grafts, 21 with a composite autogenous and heterologous bone graft, and the other 91 using deprotenized bovine bone mineral only. All of these included a resorbable collagen membrane (Table 4 and Figure 5).

Table 4

Procedure of bone regenerative techniques related to the implant treatment*

Procedure of bone regenerative techniques related to the implant treatment*
Procedure of bone regenerative techniques related to the implant treatment*

After an average of 453 days (some patients could not undergo the prosthetic procedure on time because of economic reasons) following implant placement, the permanent restorations were cemented onto the abutments. Provisionals were placed after an average of 135 days following implant placement. The complication rate was 0.53% after approximately 4 years following implant placement. This included 1 case of peri-implantitis at about 2 years, and 1 case of screw loosening 1 year after final prosthesis delivery. The implant with peri-implantitis was removed and replaced. Therefore, the implant survival rate at 46 months was 99.7%.

Statistical analysis

The data were statistically evaluated using a Student t test, Pearson correlation test, and scatterplot graphics.25  The statistical analysis was performed using Excel, Numbers, and SPSS 19 programs.

Insertion torque was statistically significant for implant diameter (P = .017 Pearson 2-tailed test) (Figure 6), that is, insertion torque increased as implant diameter increased. No significant relation was found between implant length and insertion torque (P = .933 Pearson 2-tailed test).

Similarly, there was a strong correlation (P = .000 Pearson 2-tailed test) between insertion torque and bone quality. In particular, the increase in bone density coincided with a steady increase in implant insertion torque (Figure 7). Except for a small number of patients, the implant design showed adequate levels of primary stability, even in areas of poor bone quality.

Discussion

In accordance with the literature,2628  the present study confirms the reliability of implant therapy with regards to medium- and long-term survival. This study also confirms the reliability of the internal octagon connection. Only 1 case of abutment screw loosening was found out of 377 implants. The incidence of screw loosening in this study is much better than that found in some studies reporting the performance of the classic external and internal hexagon connections.8,9,2830 

Two assumptions may be made about the favorable performance of the evaluated connection. First, the use of the octagon may provide a smaller tolerance to rotation6  and, therefore, less micromovement compared with the hexagonal connection. The octagon connection in this study is unique as the coronal octagon is used for placing the implant and the apical octagon for prosthetic connection. Second, implant stability is crucial to establish osseointegration.3133  Based on the findings of the present study, sufficient primary stability and limited micromovement are essential in achieving osseointegration, especially in immediate loading cases.33 

Some studies34,35  report an acceptable range of implant micromovement between 50 μm and 100 μm, beyond which bone cells and newly formed vessels undergo rupture, which results in bone resorption and formation of interposed fibrous tissue. It has also been shown that in poor-quality bone, lateral forces can cause micromovement up to 250 μm, which is harmful for osseointegration.3638 

Bone density of the implant site influences the amount of bone-to-implant contact and, therefore, is a variable factor for implant stability.32  The findings of this study show primary stability is easier to achieve in dense bone and more difficult to achieve in poor-quality bone.39,40  It is well understood that bone-to-implant contact is critical for long-term clinical success. Studies suggest that implant diameter is an important variable for obtaining good primary stability.30,40 

Initial stability can be quantified by insertion torque value41 ; therefore, it can be assumed that higher insertion torque corresponds to a smaller amount of initial micromovement. According to the statistical findings of this study, values of low bone quality seem to correspond to less primary stability (recorded as insertion torque) with a statistically significant relationship. It can be assumed that, regardless of the insertion-site bone quality, increasing implant diameter may be a way to increase primary stability. The same assumption cannot be made for implant length. No correlations were found between implant length and primary stability. In one study, it was shown that cortical bone is 10 times more rigid than cancellous bone.42  Therefore, it seems that diameter, as opposed to length, plays a more important role in achieving primary stability because a greater amount of cortical bone can be engaged using a wider implant. Lastly, bone augmentation may also aid in increasing primary stability, thereby decreasing the incidence of failures, especially in areas with poor bone density.4345 

Conclusion

This 4-year multicenter prospective clinical study reports excellent survival rates of the evaluated implant system in various clinical situations. In addition, the evaluated implant system seems to reduce the incidence of prosthetic screw loosening. Within the limitations of this study a wider dental implant diameter corresponded to greater implant primary stability. Therefore, for certain anatomic conditions, the use of a wider implant is recommended to increase primary stability. Implant length does not appear critical in obtaining primary stability.

Abbreviation

     
  • PSI

    Periodontal Screening Index

References

References
1
Albrektsson
T.
A multicenter report on osseointegrated oral implants
.
J Prosthet Dent
.
1988
;
60
:
75
84
.
2
Rutkowski
JL.
American Academy of Implant Dentistry Foundation supports basic and clinical research
.
J Oral Implantol
.
2012
;
38
:
437
438
.
3
Davarpanah
M
,
Martinez
H
,
Etienne
D
,
et al.
A prospective multicenter evaluation of 1,583 3i implants: 1- to 5-year data
.
Int J Oral Maxillofac Implants
.
2002
;
17
:
820
828
.
4
Mangano
C
,
Mangano
F
,
Shibli
JA
,
et al.
Prospective evaluation of 2,549 morse taper connection implants: 1- to 6-year data
.
J Periodontol
.
2011
;
82
:
52
61
.
5
Mangano
C
,
Mangano
F
,
Piattelli
A
,
Iezzi
G
,
Mangano
A
,
La Colla
L.
Prospective clinical evaluation of 1920 Morse taper connection implants: results after 4 years of functional loading
.
Clin Oral Impl Res
.
2009
;
20
:
254
261
.
6
Zipprich
H
,
Weigl
P
,
Lange
B
,
Lauer
HC.
Micromovements at the implant-abutment interface: measurement, causes and consequences
.
Implantologie
.
2007
;
15
:
31
46
.
7
Heckmann
SM
,
Linke
JJ
,
Graef
F
,
Foitzik
CH
,
Wichmann
MG
,
Weber
HP.
Stress and inflammation as a detrimental combination for peri-implant bone loss
.
J Dent Res
.
2006
;
85
:
711
716
.
8
Balfour
A
,
O'Brien
GR.
Comparative study of antirotational single tooth abutments
.
J Prosthet Dent
.
1995
;
73
:
36
43
.
9
Levine
RA
,
Clem
DS
III,
Wilson
TG
Jr,
Higginbottom
F
,
Solnit
G.
Multicenter retrospective analysis of the ITI implant system used for single-tooth replacements: results of loading for 2 or more years
.
Int J Oral Maxillofac Implants
.
1999
;
14
:
516
520
.
10
Karlsson
U
,
Gotfredsen
K
,
Olsson
C. A
2-year report on maxillary and mandibular fixed partial dentures supported by Astra Tech dental implants. A comparison of 2 implants with different surface textures
.
Clin Oral Implants Res
.
1998
;
9
:
235
242
.
11
Wannfors
K
,
Smedberg
JI.
A prospective clinical evaluation of different single-tooth restoration designs on osseointegrated implants. A 3-year follow-up of Brånemark implants
.
Clin Oral Implants Res
.
1999
;
10
:
453
458
.
12
Schwarz
MS.
Mechanical complications of dental implants
.
Clin Oral Implants Res
.
2000
;
11
(
suppl 1
):
156
158
.
13
Pjetursson
BE
,
Tan
K
,
Lang
NP
,
Brägger
U
,
Egger
M
,
Zwahlen
M.
A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an observation period of at least 5 years
.
Clin Oral Implants Res
.
2004
;
15
:
667
676
.
14
Jung
RE
,
Pjetursson
BE
,
Glauser
R
,
Zembic
A
,
Zwahlen
M
,
Lang
NP.
A systematic review of the 5-year survival and complication rates of implant-supported single crowns
.
Clin Oral Implants Res
.
2008
;
19
:
119
.
15
Ivanoff
CJ
,
Gröndahl
K
,
Sennerby
L
,
Bergström
C
,
Lekholm
U.
Influence of variations in implant diameters: a 3- to 5-year retrospective clinical report
.
Int J Oral Maxillofac Implants
.
1999
;
14
:
173
180
.
16
Himmlová
L
,
Dostálová
T
,
Kácovský
A
,
Konvicková
S.
Influence of implant length and diameter on stress distribution: a finite element analysis
.
J Prosthet Dent
.
2004
;
91
:
20
25
.
17
Baggi
L
,
Cappelloni
I
,
Di Girolamo
M
,
Maceri
F
,
Vairo
G.
The influence of implant diameter and length on stress distribution of osseointegrated implants related to crestal bone geometry: a three-dimensional finite element analysis
.
J Prosthet Dent
.
2008
;
100
:
422
431
.
18
Cicciù
M
,
Risitano
G
,
Maiorana
C
,
Franceschini
G.
Parametric analysis of the strength in the “Toronto” osseous-prosthesis system
.
Minerva Stomatol
.
2009
;
58
:
9
23
.
19
Ding
X
,
Liao
SH
,
Zhu
XH
,
Zhang
XH
,
Zhang
L.
Effect of diameter and length on stress distribution of the alveolar crest around immediate loading implants
.
Clin Implant Dent Relat Res
.
2009
;
11
:
279
287
.
20
Jovanovic
SA
,
Spiekermann
H
,
Richter
EJ.
Bone regeneration around titanium dental implants in dehisced defect sites: a clinical study
.
Int J Oral Maxillofac Implants
.
1992
;
7
:
233
245
.
21
Turkyilmaz
I
,
Sennerby
L
,
Tumer
C
,
Yenigul
M
,
Avci
M.
Stability and marginal bone level measurements of unsplinted implants used for mandibular overdentures: a 1-year randomized prospective clinical study comparing early and conventional loading protocols
.
Clin Oral Implants Res
.
2006
;
17
:
501
505
.
22
Passeri
G
,
Cacchioli
A
,
Ravanetti
F
,
Galli
C
,
Elezi
E
,
Macaluso
GM.
Adhesion pattern and growth of primary human osteoblastic cells on five commercially available titanium surfaces
.
Clin Oral Implants Res
.
2010
;
21
:
756
765
.
23
Lekholm
U
,
Zarb
G.
Patient selection and preparation
.
In
Branemark
GA
,
Zarb
G
,
Albrektsson
T
,
eds
.
Tissue Integrated Prosthesis: Osseointegration in Clinical Dentistry
.
Chicago, Ill
:
Quintessence Publishing;
1985
:
199
210
.
24
Eickholz
P
Hörr
T
,
Klein
F
,
Hassfeld
S
,
Kim
TS.
Radiographic parameters for prognosis of periodontal healing of infrabony defects: two different definitions of defect depth
.
J Periodontol
.
2004
;
75
:
399
407
.
25
Neely
JG
,
Hartman
JM
,
Forsen
JW
Jr,
Wallace
MS.
Tutorials in clinical research: VII. Understanding comparative statistics (contrast)—part B: application of T-test, Mann-Whitney U, and chi-square
.
Laryngoscope
.
2003
;
113
:
1719
1725
.
26
Guckes
AD
,
Scurria
MS
,
Shugars
DA.
A conceptual framework for understanding outcomes of oral implant therapy
.
J Prosthet Dent
.
1996
;
75
:
633
639
.
27
Branemark
PI
,
Svensson
B
,
van Steenberghe
D.
Ten-year survival rates of fixed prostheses on four or six implants ad modum Branemark in full edentulism
.
Clin Oral Implants Res
.
1995
;
6
:
227
231
.
28
Geckili
O
,
Bilhan
H
,
Bilgin
T. A
24-week prospective study comparing the stability of titanium dioxide grit-blasted dental impants with and without fluoride treatment
.
Int J Oral Maxillofac Implants
.
2009
;
24
:
684
688
.
29
Mangano
C
,
Bartolucci
EG.
Single tooth replacement by morse taper connection implants: a retrospective study of 80 implants
.
Int J Oral Maxillofac Implants
.
2001
;
16
:
675
680
.
30
Meredith
N.
Assessment of implant stability as a prognostic determinant
.
Int J Prosthodont
.
1998
;
11
:
491
501
.
31
Becker
W
,
Sennerby
L
,
Bedrossian
E
,
Becker
BE
,
Lucchini
JP.
Implant stability measurements for implants placed at the time of extraction: a cohort, prospective clinical trial
.
J Periodontol
.
2005
;
76
:
391
397
.
32
Ostman
PO
,
Hellman
M
,
Wendelhag
I
,
Sennerby
L.
Resonance frequency analysis measurements of implants at placement surgery
.
Int J Prosthodont
.
2006
;
19
:
77
83
.
33
Barone
A
,
Rispoli
L
,
Vozza
I
,
Quaranta
A
,
Covani
U.
Immediate restoration of single implants placed immediately after tooth extraction
.
J Periodontol
.
2006
;
77
:
1914
1920
.
34
Soballe
K
,
Hansen
ES
,
Brockstedt-Rasmussen
H
,
Bunger
C.
Hydroxyapatite coating converts fibrous tissue to bone around loaded implants
.
J Bone Joint Surg Br
.
1993
;
75
:
270
278
.
35
Szmukler-Moncler
S
,
Piattelli
A
,
Favero
GA
,
Dubruille
JH.
Considerations preliminary to the application of early and immediate loading protocols in dental implantology
.
Clin Oral Implants Res
.
2000
;
11
:
12
25
36
Engelke
W
,
Decco
OA
,
Rau
MJ
,
Massoni
MC
,
Schwarzwaller
W.
In vitro evaluation of horizontal implant micromovement in bone specimen with contact endoscopy
.
Implant Dent
.
2004
;
13
:
88
94
.
37
Trisi
P
,
Perfetti
G
,
Baldoni
E
,
Berardi
D
,
Colagiovanni
M
,
Scogna
G.
Implant micromotion is related to peak insertion torque and bone density
.
Clin Oral Implants Res
.
2009
;
20
:
467
471
.
38
Trisi
P
,
De Benedittis
S
,
Perfetti
G
,
Berardi
D.
Primary stability, insertion torque and bone density of cylindric implant ad modum Branemark: is there a relationship? An in vitro study
.
Clin Oral Implants Res
.
2011
;
22
:
567
570
.
39
Farré-Pagés
N
,
Augé-Castro
ML
,
Alaejos-Algarra
F
,
Mareque-Bueno
J
,
Ferrés-Padrò
E
,
Hernàndez-Alfaro
F.
Relation between bone density and primary implant stability
.
Med Oral Patol Oral Cir Bucal
.
2011
;
16
:
62
67
.
40
Bilhan
H
,
Geckili
O
,
Mumcu
E
,
Bozdag
E
,
Sunbuloglu
E
,
Kutay
O.
Influence of surgical technique, implant shape and diameter on the primary stability in cancellous bone
.
J Oral Rehabil
.
2010
;
37
:
900
907
.
41
Turkyilmaz
I.
A comparison between insertion torque and resonance frequency in the assessment of torque capacity and primary stability of Branemark system implants
.
J Oral Rehabil
.
2006
;
33
:
754
759
.
42
Misch
CE
,
Dietsh-Misch
F
,
Hoar
J
,
Beck
G
,
Hazen
R
,
Misch
CM.
A bone quality-based implant system: first year of prosthetic loading
.
J Oral Implantol
.
1999
;
25
:
185
197
.
43
Fanuscu
MI
,
Chang
TL
,
Akca
K.
Effect of surgical techniques on primary implant stability and peri-implant bone
.
J Oral Maxillofac Surg
.
2007
;
65
:
2487
2491
.
44
Cicciù
M
,
Beretta
M
,
Risitano
G
,
Maiorana
C.
Cemented-retained vs screw-retained implant restorations: an investigation on 1939 dental implants
.
Minerva Stomatol
.
2008
;
57
:
167
179
.
45
Andrés-Garcia
R
,
Vives
NG
,
Climent
FH
,
et al.
l. In vitro evaluation of the influence of the cortical bone on the primary stability of two implant systems
.
Med Oral Patol Oral Cir Bucal
.
2009
;
14
:
93
97
.