Marginal Bone Loss in Implants Placed in Bone Level and Tissue Level
Phase: NA
Conditions: Dental Implant, Implant Stability
Sponsor: University of Barcelona

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Title: 
Analysis of marginal bone loss in implants placed at the soft tissue-bone tissue level. 
 
Researchers: 
 
 
Main:  
Ahmed Samir Mabrouk Oraby Elkattan 
 
 
Collaborators:          
 
José López López  
 
Raúl Ayuso Montero 
 
Xavier Roselló Llabrés 
 
Monica Blázquez 
 
 
 
Centers:  
 
Hospital Dentistry University of Barcelona (HOUB). 
Faculty of Medicine and Health Sciences, Dentistry, University of 
Barcelona. 
 
 
 
 
2nd version of the Protocol: July,01, 2022. 
 

2 
 
 
 
 
 
 
SUMMARY 
The subcrestal placement implant has a positive impact on papilla formation and allows 
an emergence profile suitable for an aesthetic restoration. Its placement allows the 
implant-abutment interface to be in a position that contributes to bone remodeling in the 
neck region of the implant, compared to implants placed at bone level (bone-level,crestal 
placement). Marginal bone loss from implants placedcrestal or subcrestal has shown 
conflicting results in recent studies. 
 
1.- BACKGROUND OF THE SUBJECT 
Dental implants have been introduced as an option for replacing missing teeth, since the 
initial studies of Professor Per-Ingvar Brånemark in the 1950s, there are multiple studies 
that support it, including (Andersson B, 1995; Arlin M, 1993; Noack et al, 1999; Jemt T, 
2017; The accepted criteria for evaluating implant success were proposed by Albrektsson 
et al. (Albrektsson et al, 1986), who to identify clinical evidence of successful 
osseointegration and implant survival, suggested that a marginal bone loss of less than 
1.5 mm in the first year and 0.2 mm in the following years, it is acceptable after implant 
loading (Díaz-Sánchez et al, 2019). Over the past three decades, implant success has been 
evaluated by survival rates, prosthesis stability, radiographic bone loss, and the absence 
of infection in the peri-implant soft tissues (Albrektsson et al, 1986; Smith and Zarb 1989; 
Buser et al, 1990, Albrektsson and Zarb 1998, Misch et al, 2008; The progressive 
knowledge of patients has increasingly required treatments that offer better aesthetics and 
comfort, making implantology a demanding field, where obtaining osseointegration or 
meeting the success criteria of implants highlighted by the lack of pain and infection, 
absence of radiolucency and mobility and possibility of restoration (Buser et al, in the 
1990s). Thus, new parameters have been introduced to evaluate the long-term success of 
implant restorations. Including health status and natural-looking peri-implant soft tissues, 
prosthodontic parameters, aesthetics and patient satisfaction. However, osseointegration 
remains the predominant parameter in implantology (Furhauser et al, 2005; Meijer et al, 
2005; Annibali et al, 2009; Belser et al, 2009). 
Various authors describe that the position of the implant with respect to the crestal bone 
is a fundamental factor to preserve the bone in the future (Pontes et al, 2008; Novaes et 
al, 2009; De Siqueira et al, 2017; Wennerberb et al. al, 2003; Although, regarding this 
issue there continues to be controversy. Thus, some authors recommend placing the 

3 
 
implant below the crest of the bone (i.e., subcrustal placement). They argue that this 
position will contribute to the preservation of the mucosa (Pontes et al, 2008), helping 
to obtain an ideal emergence profile in aesthetic areas (Novaes et al, 2009; Di Siquerira 
et al, 2017) and preventing the surface of the implant is exposed; at the same time that 
the presence of mucositis or peri-implantitis is reduced (Wennerberg et, 2003). A 
possible reason for this could be bacterial colonization of the implant-abutment 
junction, where an inflammatory infiltrate occurs (Do-Nascimento et al, 2012; Hermann 
et al, 2000; Broggini et al, 2003). This characteristic, in conjunction with a low oxygen 
concentration, could create an ideal ecosystem for the proliferation of anaerobic bacteria 
(Piattelli et al, 2003). On the other hand, it could be speculated that deeper implant 
placement may correlate with deeper pockets and soft tissue inflammation (Siqueira et 
al, 2017).  
In another order of things, the connection of the implant with the abutment involves 
microspaces. These microspaces (which facilitate the accumulation of bacteria) can 
influence peri-implant bone resorption along with other factors such as surgical trauma, 
the establishment of the biological width, the design of the implant and the position of the 
implant (Palacios-Garzón et al, 2019 ; Díaz-Sánchez, et al, 2019; Buser et al., 1990). 
Studies have shown that this microgap varies between 0 and 135 μm (Dellow et al, 1997; 
Callan et al, 1998). However, what deserves special attention is that, as in teeth, the 
biological width is formed around the implants, consisting of a junctional epithelium and 
connective tissue with an average dimension of approximately 2 mm and 1–1.5 mm. 
respectively (Berglundh et al, 1991). On the other hand, different risk factors can affect 
implant lifespan, such as anatomical characteristics, chewing dynamics, and proper 
implant selection, which are important for long-term prognosis. Today, we know that 
implants with rough surfaces show a statistically higher survival rate than machined 
implants at all intervals (Levin et al, 2006). 
Maintaining the level of the crestal bone around dental implants is essential for their long-
term success and survival (Mei et al, 2017; Al Amri et al, 2017; Marcelo-Machado, et al 
2018). Factors that may showcrestal bone resorption in dental implants that affect the 
survival rate of the dental implant, such as the amount of overload stress (Stoichkov et al, 
2018), micromotion (King et al, 2002), location and bacterial infiltration of the implant-
abutment connection (Blanco et al, 2008; Kozlovsky et al, 2007; Tripodi et al, 2015), 
periodontal phenotype (Linkevicius et al, 2010), bone density (Hermann et al, 2001; 
Goiato et al, 2014), trauma surgical (Canullo et al, 2012) and maintenance of oral hygiene 
(Kozlovsky et al, 20007). In the actulaida, several treatment protocols have been proposed 
to reduce marginal bone loss around implants (Calvo-Guirado et al, 2015; Vohara et al, 
2015; Romanos et al, 2014), including implant placement by below the level of the bony 
crest (subcrestal placement) (Kutan et al, 2015). Furthermore, the subcrestal implant also 
has a positive impact on papilla formation and allows for an adequate emergence profile 
for better aesthetic restoration (Vela-Nebot et al, 2006; Koutouzis et al, 2014). In this 
placement the implant-abutment interface is in a position that contributes to bone 
remodeling in the neck region of the implant compared to implants placed at bone level 
(crestal placement) (Outouzis et al, 2011; Charalampakis et al, 2014). On the other hand, 

4 
 
marginal bone loss from subcrustal implants compared to crests has shown contradictory 
results in recent studies (Gale et al 2013). Thus, some studies reported similar bone levels 
for both implant placement techniques (Casagrande et al, 2020). Therefore, we believe it 
is necessary to continue researching in this field, to make decision-making easier for the 
clinician. 
 
2-JUSTIFICATION 
Various treatment protocols have been proposed to reduce marginal bone loss around implants, 
including placement of implants below the level of the bone crest (subcrestal placement). The 
supracrestal implant also has a positive impact on papilla formation and allows an emergence 
profile suitable for an aesthetic restoration. Allowing the implant-abutment interface to be in a 
position that contributes to bone remodeling in the implant neck region compared to implants 
placed at bone level (crestal placement). Marginal bone loss from implants placed 
bestially/subcrestally has shown conflicting results in recent studies.  In this study we intend to 
evaluate bone loss in 100 Tissue level implants from two different commercial companies: 
Straumann bone level® with the Bio horizon Tissue level® implant. Buying the data obtained 
with the existing literature. 
3- HYPOTHESIS 
3.1- Main hypothesis 
Null hypothesis:  
Two different brands of implants behave in the same way in terms of marginal bone loss, if they 
are placed based on the indications specified by the manufacturer.  
Alternative hypothesis:  
Two different brands of implants behave in the same way in terms of marginal bone loss, if they 
are placed based on the indications specified by the manufacturer.: 
 
3- HYPOTHESIS 
3.1- Main hypothesis 
Null hypothesis: A brand of implant behaves in the same way in terms of marginal bone loss, if 
it is placed according to the indications specified by the manufacturer (crestal level or 
supracestal level). 

5 
 
Alternative hypothesis:  
A brand of implant does not behave in the same way in terms of marginal bone loss, if it is placed 
according to the indications specified by the manufacturer (crestal level or supracestal level). 
4-OBJECTIVES 
4.1 Main objective: 
To evaluate marginal bone loss in two different brands of implants placed at the bone level. 
 
4.2 Secondary objectives: 
• Relationship between marginal bone loss and suprabony soft tissue in mm. 
• Relationship between marginal bone loss and ISQ value at the time of implantation. 
• Relationship between marginal bone loss and torque (in Newton) at the time of implantation. 
• Relationship between marginal bone loss and implant location. 
• Relationship between marginal bone loss and the degree of periodontal disease. 
• Relationship between marginal bone loss and systemic diseases. 
• Relationship between marginal bone loss and smoking 
 
5- MATERIAL AND METHOD 
5.1- Study design 
It is a prospective clinical study to compare two implants from two different brands of a similar 
design for their implantation [tissue level] and to evaluate the marginal bone loss of each dental 
implant in mm. 96 patients will be analyzed (an expected N of 48 per group, hoping to reach at 
least 100 implants per arm). See calculation of N in point 5.7. 
 
5.2- Study population  
The patients will be collected from patients who attend the master's degree in medicine, surgery 
and Oral Implantology, requesting implant-supported treatment. The study population will consist 
of patients who require treatment with dental implants, either partially or completely edentulous 
and who accept their placement and participation in the study.4.2.1 Inclusion / exclusion criteria 
 
5.3-Inclusion/exclusion criteria 
Inclusion: 
• Patients of both sexes, over 18 years of age, who need dental implant placement for prosthetic 
rehabilitation. Whether partially or completely in both the maxilla and the mandible. 

6 
 
• Patients with residual alveolar ridge with at least 8 mm of bone height and 4 mm of width. 
• Patients must have the ability to understand and decide at the time of voluntarily signing the 
informed consent before carrying out any intervention related to the study. 
• Patients who, after being informed about the objectives and procedures of the research, agree, 
will sign the informed consent form. And they are ready to carry out the different study visits. 
 
Exclusion: 
• Patients with uncontrolled systemic diseases (ASA ≥ III). 
• Patients who do not have 8mm bone height and/or 4mm width 
• Patients who require bone regeneration 
• Patients with severe periodontal disease or acute pericoronitis. 
• Pregnant and breastfeeding women. 
• Patients with Deficient or Inadequate Oral Hygiene. 
• Patients with severe bruxism. 
• Patients taking bisphosphonates or other antiresority medications. 
• Smoker of more than 10 cigarettes/day. 
• Patients with uncontrolled diabetes mellitus. 
• Psychiatric illnesses or unrealistic expectations. 
• Immunocompromised or immunosuppressed patient. 
5.4.-Recruitment 
The sample will be for convenience and will be obtained from patients of the Hospital 
Odontològic Universitat de Barcelona (HOUB) who come to the service of the Master of 
Dentistry in Oral Medicine, Surgery and Implantology. Once the protocol is approved by the 
Ethics and Research Committee with Medicines and Health Products of the same HOUB 
(CEIm-HOUB), the recruitment of study participants will begin, estimated to take one year and 
2 months, starting in November 2022. 
5.5.- Procedures 
5.5.1 First session and recruitment 
In this first session, before starting surgery and prosthodontic treatment, a thorough medical 
history will be taken. Each patient will be examined by extra-oral and intra-oral examination, in 
addition to the evaluation of their respective orthopantomography and cone beam computed 
tomography (CBCT), to evaluate the level of height and width of the bone for the placement of 
dental implants. This process will be carried out by the main researcher and supervised by another 
expert in Dentistry. Study participants who meet the inclusion criteria will then be recruited and 
asked if they wish to participate.  Each of them will be given the following records. 
If the patient meets the criteria and is interested, they will sign the informed consent and will be 
randomized using a randomization table of 10 in 10 implants [e.g.: randomization table 
ABBAABBBAB] to place one type or another of implant: 

7 
 
 
 
 
5.5.2 Second session  
The patient will come to the Hospital for primary impressions with alginate. Then a cast will made 
with gypsum for study the case and bite of the patient will be taken with wax to record it.  
 
5.5.3Third session  
The patient will come to the Hospital to operate the surgery within 15-20 days after having the 
study caste revised by a dentist and specialist from the fixed department. The patient will have 
temporary prothesis (Fixed or Removable) after the surgery of the implant. A periapical X-Ray 
will be taken immediately after the surgery to control the marginal bone loss. With the respect to 
accepted criteria for the assessment of implant success were proposed by Albrektsson and 
colleagues (Albrektsson et al., 1986), which to identify clinical evidence of successful 
osseointegration and survival of implants, suggested that a marginal bone loss of less than 1.5 
mm in the first year and 0.2 mm in the following years is acceptable after implant loading. 
5.5.4 Fourth session  
Once the osseointegration time has elapsed, 3 months ± 15 days (in the mandible) and 4 months 
± 15 days (in the maxilla), new clinical and radiographic measurements will be taken and then 
the rehabilitation phase will begin. The visits will be those corresponding to the required 
prosthetic treatment (fixed or removable), carried out according to the usual procedures and 
techniques of the prosthodontic service. 
5.5.5 Fith session  
After placing the prosthesis on the patient, it will be reviewed every 3 months ± 15 days, for 2 
years, to establish controls. 
 
 
 
 
 
 

8 
 
5.5.6 Sample's size calculation 
 
Reference points for calculating marginal bone loss. Taken with permission from the author of 
Lina Dumanova's TFG. Red arrow, known mean of the implant. Green arrows reference the 
crestal bone and the marginal loss that occurred that allows us to compare at different times of 
the study. 
5.6- Description of the treatment or intervention: drugs or techniques to be used. 
- 
All patients will be anesthetized with 2% articaine with epinephrine, 
- 
Regarding medication dispensed: 
- 
Amoxicillin 1000 mg cps /8 hours for 7 days. (Patients allergic to Amoxicilllin, 
we prescribe Clindamicina 600 mg cps /8H / 7 days). 
- 
Dexketroprofeno 25 mg cps /8 hours for 7 days.  
- 
Omperazol 25 mg cps / 8H/ 7 days for the stomach.  
- 
As rescue medication: Paracetamol 1000 mg cps /8 hours for 7 days and/or 
Metamizol 650 mg cps 1/8 hours. 
- 
Rinse with 0.12% chlorhexidine 2 times/7 days. 
 
5.7.- Sample calculation 
According to data obtained in the study by Natalia Palacios-Garzon et al, 2020 (taking into 
account that both are internally connected implants), in order to detect changes of 0.2mm we 
would need: Accepting an alpha risk of 0.05 and a beta risk of 0.2 in a bilateral contrast, 48 
subjects (implants) in the first group and 48 (Implants) in the second are needed to detect a 
difference equal to or greater than 0.2 units. 
The common standard deviation is assumed to be 0.34. A loss to follow-up rate of 5% has been 
estimated. 
 
5.8.- Statistical analysis 
The variable data will be entered into the Excel program of the Microsoft Office 2019 Package 
(Microsoft Corporation, Washington, USA, 2013) and will be analyzed with the SPSS 26.0 
program for Windows (SPSS, Illinois, USA, 2019). 
The data collected will be processed using the STATA 14.0 statistical package. A descriptive 
analysis of the qualitative and quantitative variables will be carried out. The Kolmogorov-
Smirnov test will be used to analyze the normality of the measurements. 
The relationship between bone loss and implant position will be analyzed using parametric t-
test. 

9 
 
The level of statistical significance chosen is 5% (α = 0.05). To evaluate the association 
between the dependent variable bone loss from T0 to T2 and successive Ts and the independent 
variables implant A, Implant B placement, a multiple linear regression analysis will be used. 
All variables considered to potentially affect the study relationship, such as sex, age, and smoking, 
will be used as control variables in the regression; the number of cigarettes per day, maxilla or 
mandible, ISQ [implant stability value] and contact of the mesial and distal implant (penseic ade 
dinets and/or implants by mesial and distal) 
5.9- Schedule 
 
 
2022 
2023 
 
En 
Feb 
Mar 
Abr 
May 
Jun 
Jul 
Agos 
Sep 
Oct 
Nov 
Dic 
En 
Feb 
Mar 
Abr 
May 
Jun 
Jul 
Agos 
Sep 
Oct 
Nov 
Dic 
Reclutamiento 
de 
participantes 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2024 
2025 
 
En 
Feb 
Mar 
Abr 
May 
Jun 
Jul 
Agos 
Sep 
Oct 
Nov 
Dic 
En 
Feb 
Mar 
Abr 
May 
Jun 
Jul 
Agos 
Sep 
Oct 
Nov 
Dic 
Recopilación 
de datos 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
En 
Feb 
Mar 
Abr 
May 
Jun 
Jul 
Agos 
Sep 
Oct 
Nov 
Dic 
En 
Feb 
Mar 
Abr 
May 
Jun 
Jul 
Agos 
Sep 
Oct 
Nov 
Dic 
Análisis de los 
datos 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5.0- Specification of the acceptance of the national and international ethical norms 
The researchers agree that each participating subject will be treated and controlled following the 
protocol authorized by the Ethics and Research Committee for Medicines and Health Products of 
the Hospital Odontològic of the University of Barcelona (CEIm-HOUB) and the Declaration of 
Helsinki of ethical principles for medical research in humans by the World Medical Association 
(64ª General Assembly, Fortaleza, Brazil, October 2013). 
 
5.1- Economic report 
 
Cost of rehabilitative prosthetic treatment paid by the patient.  
 
Administrative costs: in charge of the Master of Dentistry in Medicine surgery and 
Implant and the doctoral student. 
 
Material costs: by the Master of Dentistry in Medicine surgery and Implant and the 
doctoral student. 
 
o 
Ortopantograhia: 31€. 
o 
CBCT para un cuadrante: 97€. 
o 
CBCT para un mono-implant(Dependente en el caso): 81 €. 
o 
Impressional Alginato Aligsul:  10€. 
o 
Encerarlo (wax up) GEO CLASSIC gris-OPCA 75GR:20 €. 
o 
Dental Gypsum (Snow White plaster): 46€. 

10 
 
o 
Implanto Tipo A: 690€. 
o 
Protesis:830€. 
o 
Articulado papel (PAPEL BK 01 AZUL 300 HOJAS 0,2mm): 21€. 
o 
Silicona Optosil P Plus (Heraeus Kulzer GmbH, Hanau, Germany): 80€. 
o 
Silicona Zetalabor hard 85 shore A (Zhermack, Badia Polesine, Italy): 120€. 
o 
Guantes de látex (Medicaline, Castellón, España): 180€. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

11 
 
 
5.2- Data collection sheet 
 
PERSONAL DATA 
 
 
 
 
CODE:  
 
 
 
 
IN SESSION: 
NUMBER: 
 
 
 
 
 
SURNAMES: 
DATE:  
 
 
 
 
EXAMINER: 
DATE OF BIRTH (AGE): 
 
 
SEX: Man□ Woman □ 
PHONE: 
 
 
 
 
 
E-MAIL: 
 
TYPE OF PATIENT: ASA I □ ASA II □ ASA III □ ASA IV □ ASA V □ 
 
PRIMARY DIAGNOSIS (DATE: mm / yyyy): 
_____________________________________________________________________________
__ 
_____________________________________________________________________________
__ 
 
SURGERY TREATMENT (DATE: mm / yyyy): 
_____________________________________________________________________________
__ 
_____________________________________________________________________________
__ 
 
 
 
Nº TEETH TO BE REHABILITATED WITH A PROSTHETIC: __prosthetic units. 
 
 
TYPE OF PROSTHESIS:__________________________. 
 
 
 
 
6- BIBLIOGRAPHY 

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