Maxillary posterior area is the most challenging site for dental implant placement. Indeed, complex remodeling processes, resulting in changes of the maxillary sinus and shape of the alveolar ridge will cause difficulties in rehabilitating the posterior maxillae sites. Various techniques have been proposed in order to achieve the necessary bone volume for the placement of long term successful implants. However, unbalanced crown to implant ratio remains a risk factor after successful dental implants installation following sinus graft. No study on humans assessed the effect of apical positioning of the implants in posterior grafted sites (sinus graft or sinus graft + vertical GBR) on the following clinical parameters: The peri-implant bone remodeling (vertical bone loss (mm) and probing depth (mm) around the implants, crown bulkiness, emergence profile and crown height, and Patients satisfaction, food impaction (PROM)).

This study will elucidate these points and based on the parameter's results, suggest a treatment based classification facilitating the treatment decision-making of the clinicians in case of an atrophic posterior maxilla; aiming to ensure a long-term successful supra-implant rehabilitation which will maintain its bio-mechanically and biological success.

1. INSTITUTION Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon Cranio-Facial Research Laboratory, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon.

2. TYPE OF PROJECT Master's degree in periodontology

3. PROJECT TITLE Digital planning and clinical assessment of the treated atrophic posterior maxilla with a sinus lift procedure: a cross-sectional study.

4. RESEARCH AND PUBLICATION TEAM

   Director:

   Pr. Nadim Mokbel, DDS, MSc, PhD Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon Nadim.mokbel@gmail.com

   Co-director:

   Dr. Abdel Rahman Kassir, DDS, MSc Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon Kassirabdelrahman@gmail.com

   Main Researcher:

   Dr Joseph Younes, DDS Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon josephryan.younes@net.usj.edu.lb

   Contributor roles in publications:

   • Joseph Younes, DDS: conceptualization of the project, handling of the measurements to be conducted, data preservation, and manuscript writing.

   Postgraduate student, Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon

   • Nadim Mokbel, DDS, MSc: conceptualization and administration of the project, data supervision, and manuscript revision.

   Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon

   • Adam Saleh, DDs, MSc: supervision of measurement handling and data preservation.

   Cranio-Facial Research Laboratory, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon.

   Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon

   • Nadine Chamas, DDS: data collection and manuscript analysis. Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon
   • Abdallah Menhall, DDS, MSc: data collection and analysis. Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon
   • Abdel Rahman Kassir, DDs, MSc: conceptualization and administration of the project, data supervision, and manuscript revision.

   Department of Periodontology, Faculty of Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon

5. TYPE OF STUDY observational, clinical and cross sectionnal study

6. FUNDINGS:

   Self-funded by the researcher

7. KEYWORDS:

   Alveolar bone atrophy, digital planning, guided bone regeneration, maxillary sinus, peri-implant disease, peri-implantitis, sinus floor augmentation.

8. GENERAL CONTEXT

   Background:

   Pneumatization of the maxillary sinus limits the quantity of alveolar bone available for implant placement and may result in a lack of primary stability and difficulty in achieving osseointegration(1).

   Indeed, the maxillary posterior area is the most challenging site for dental implant placement. Residual ridge resorption (RRR) after tooth loss is the combined result of complex remodeling processes, resulting in changes in the maxillary sinus and shape of the alveolar ridge(2,3). These morphometric changes have a big impact on the subsequent pre-prosthetic treatment and thus the focus of research since the early days of implant therapy in dentistry. The prevalence of sinus augmentation associated to implant rehabilitation was defined as 54.2% of the cases(4).

   Various techniques have been proposed in order to achieve the necessary bone volume for the placement of long term successful implants: Sinus grafting, Crestal bone augmentation achieved through vertical GBR or autogenous blocks or allografts(5).

   Although the sinus graft is very often used as a predictable and successful technique for rehabilitation of atrophic and pneumatized posterior maxilla, some challenges may arise in the case of an advanced atrophic maxilla. An unbalanced crown-to-implant ratio remains a risk factor after successful dental implants installation following sinus graft(6,7). This being said, there is a need to perform a "crestal" vertical augmentation of the maxillary posterior alveolar ridge either combined or not to a sinus grafting technique.

   The vertical crestal augmentation is recommended especially in case of severe atrophy which result in a deeper position of the implant neck (compared to the CEJ) where authors found that those implants showed more peri-implant bone loss (less success rate) (1,7).

   Augmentation technique's selection relies on a detailed pre-operative clinical and radiographic assessment of the area. Following this evaluation, the clinician will be able to select the optimal solution to ensure sustainable long-term implant rehabilitations. Several classifications based on radiological features or bone morphometry have been proposed to simplify the description of jaw resorption conditions and to facilitate the communication between clinicians(2,3,7-12). Together, these classifications provide complete guidelines for rehabilitation of the edentulous posterior maxilla but independently they are incomplete. Moreover, the implant treatment guidelines nowadays evolved. Additionally, the evolution of bone regeneration techniques made the management of both horizontal and vertical defects more predictable. This has led to the management of severe atrophic defects to obtain a satisfactory prosthetic outcome. Additionally, digitalization in dentistry is a helpful tool to plan the requirement of each clinical case and simulate the prosthetic outcome.

   The goal of our study is to evaluate the long-term success of implants placed in atrophic posterior maxillae treated with sinus grafting originally needing vertical bone augmentation.

   As a secondary objective, a digital assessment of the ideal bone augmentation project in the treated atrophic patients will be done. The recent use of milled or printed bone regenerative scaffolds (based on well-defined volumetric bone contour) will simplify and potentially add contemporary guidelines leading to a novel bone augmentation classification (when compared to Wang, Simion et al.).

9. SUMMARY DESCRIPTION OF THE SUBJECT AND APPROACH Maxillary posterior area is the most challenging site for dental implant placement. Indeed, complex remodeling processes, resulting in changes of the maxillary sinus and shape of the alveolar ridge will cause difficulties in rehabilitating the posterior maxillae sites. Various techniques have been proposed in order to achieve the necessary bone volume for the placement of long term successful implants. However, unbalanced crown to implant ratio remains a risk factor after successful dental implants installation following sinus graft. No study on humans assessed the effect of apical positioning of the implants in posterior grafted sites (sinus graft or sinus graft + vertical GBR) on the following clinical parameters: The peri-implant bone remodeling (vertical bone loss (mm) and probing depth (mm) around the implants, crown bulkiness, emergence profile and crown height, and Patients satisfaction, food impaction (PROM)).

   This study will elucidate these points and based on the parameter's results, suggest a treatment based classification facilitating the treatment decision-making of the clinicians in case of an atrophic posterior maxilla; aiming to ensure a long-term successful supra-implant rehabilitation which will maintain its bio-mechanically and biological success.

10. INNOVATIVE ASPECT OF THE STUDY As far as we know, the present study is a pilot research that will not only evaluate clinically/radiographically the long-term success of the implants placed in atrophic posterior maxillae treated with sinus grafting needing vertical bone augmentation but will also propose a classification based on radiographic digital 3D measurements and patient's response to the questionnaire, with a goal of facilitating the treatment decision-making of the clinicians in case of an atrophic posterior maxillae.

11. STUDY OBJECTIVES

    Primary objective:

    -To clinically and radiographically evaluate the long-term success of the implants placed in atrophic posterior maxillae.

    Secondary objectives:

    • To esthetically evaluate the prosthetic crowns performed on these implants.
    • To evaluate the patient's satisfaction and ease to maintain their crowns.
    • To digitally assess the proportions of the different sub-sinus bone defects classes.
    • To propose a new classification based on sub-sinus bone anatomical defect that will assist clinicians in choosing the best treatment modalities.

12. HYPOTHESIS

    • Null hypothesis (Ho): Apical implant positioning (Implant depth) in the posterior maxilla does not affect the long-term success of the implant and does not affect patient's satisfaction (PROM).
    • Alternative hypothesis (H1): There is a need to combine a crestal augmentation with a sinus grafting to achieve optimal results.

12. METHODOLOGY AND RESEARCH DESIGN 12.1. Study technique A. The first part of the study consists of recruiting a number of files of patients having placed posterior implants in an atrophic posterior maxilla treated with a sinus augmentation procedure. Patient's Cone Beam CTs will be retrieved from the Saint Joseph university radiology center database.

A total of 125 implants will be included in the study. Patients will be recalled for examination:

We will measure radiographically the peri-implant marginal bone remodeling (mm) using as a reference the platform of the implant to the first bone to implant contact. We will then measure the peri-implant probing depth (mm) with a Hu-Friedy Perio Probe PCP UNC15

1. periodontal probe going parallel to the axis of the implant.
2. The bleeding on probing will also be analyzed around the implants.
3. We will measure the supra-implant restoration bulkiness and height (mm) by measuring the emergence profile angle. A straight line will be drawn along the mesial and distal edge of the long axis of the implant, and the included angle between the lines tangent to the contour of the prosthesis is the emergence angle, and the mesial and distal emergence angles of the prosthesis are measured. (Fig 1)

Figure 1. Measurement of the emergence angle. Lm: the implant's long axis line in the mesial site; Ld: the implant's long axis line in the distal site; Pm: the lines tangent to the contour of the prosthesis of the mesial site; Pd: the lines tangent to the contour of the prosthesis of the distal site; ∠M: prosthetic emergence angle of the mesial site; ∠D: prosthetic emergence angle of the distal site.

B. A questionnaire will be given to the patients clinically evaluated and consists of 4 questions:

1. Do you feel that the restored tooth is bigger than the neighboring teeth? Yes No

2. Do you feel any kind of discomfort (bleeding or swelling)? Yes No Sometimes

3. Do you feel any food impaction in the ROI (region of interest)? Yes No

4. Is it easy to maintain oral hygiene? Yes No

   C. A digital analysis of CBCTs:

   It will be done by Exporting the CBCT Dicom files to 3D Slicer and Bluesky Bio Softwares.

   The following measurements will be done:

   A- The sub-sinus Residual Bone Height. B- Distance from the CEJ of neighboring teeth to the top of the Crest. C- Digital Drawing of the prosthetic project. D- 3D Digital Drawing of the Bone Crest Curve. E- The distance of the Top of the Crest and the Sinus floor. F- Distance from the crestal edge to the ideal crown position. G- 3D digital simulation of bone graft shape (Allogenic or xenogenic Bone blocks or rigid, reinforced membranes or innovative digitally-designed (Yxoss, or printed material housing (zircone or Peek)).

   Wax up (according to the distance between the CEJ line and the bone crest, and the Spee curve) and the implant placement simulations)

   Drawing of the CEJ line and the vertical line (distance between the residual crest to the wax up teeth)

   Drawing of the vertical line between the residual crest and the sinus floor

   Depending on the results obtained, we will propose a classification facilitating the treatment decision-making of the clinicians in atrophic posterior maxillae.

   12.2. Description of study population

   Sample size:

   To calculate the sample size required we will be using Epi Info 7 StatCalc functions for a population survey. In the absence of similar studies, we will assume an expected frequency of perfect success of an implant in our case to be 20%. Based on the 20% expected frequency, a confidence interval of 95%, a margin of error 7%, the minimal sample size calculated for the current study to achieve representative sample will be 125 implants.

   Inclusion criteria:

   - Patient aged more than 18 years.

   - Partially edentulous patients having an implant rehabilitation treated with a sinus lift procedure in the atrophic posterior maxilla.

   - Patient with no systemic disease that contraindicate the surgical procedure as uncontrolled diabetes mellitus, bleeding disorders, recent myocardial infarction, head and neck radiation, and mental disorders.

   Exclusion Criteria:

   - Fully Edentulous patients.

   - Patients presenting sinus pathologies (sinusitis, thickening of the membrane).

   - Patient smoking more than 20 cigarettes.

   - Patient taking systemic drugs that could affect bone healing as immune suppressive drugs and bisphosphonates.

   - Patient with systemic disease that contraindicate the surgical procedure as uncontrolled diabetes mellitus, bleeding disorders, recent myocardial infarction, head and neck radiation, and mental disorders.

   12.3. Description of the variables

   Primary variable:

   • The peri-implant marginal bone remodeling (bone loss (mm)).
   • Pocket probing depth (mm).
   • Bleeding on probing.

   Secondary Variables:

   - The sub-sinus Residual Bone height (RBH-mm).

   - Distance from the CEJ of neighboring teeth to the top of the Crest (mm).

   - Distance from the Top of the Crest to the ideal occlusal plane (mm).

   - Distance between the top of the Crest to the CEJ of the digitally designed crowns (mm).

   - Supra-implant crown bulkiness and height (emergence profile angle).

   - Questionnaire for the patient's satisfaction.

   Source of the variables:

   The variables will be collected by doing appropriate measurements on different employed softwares (Blue Sky Bio, Medit Design, Meshmixer, 3D Slicer) using DICOM files from CBCT scans.

   Statistical tests:

   Data is analyzed using IBM SPSS Statistics for Windows (Version 26) (IBM Corp., Armonk, NY, USA).

   All tests are two-tailed, and the level of significance alpha is set at 5%.

   • Univariate analysis: Descriptive statistics are performed using means, SD (standard deviations) and medians, IQR (interquartile ranges) for quantitative continuous variables. Categorical variables are summarized using frequency and percentages (%). The Shapiro-Wilk test will be used to assess the normality of distribution for continuous variables.

   • Bivariate analysis: Categorical data is presented in contingency tables. The Pearson Chi-Square analysis is used to test the dependence between categorical variables if condition is satisfied otherwise if condition is not satisfied, we will be using the Fisher's Exact Test.

13. Strong points This study will evaluate clinically and radiographically the apical implant positioning in the post maxilla and its effect on the long-term success, crown esthetics and the patient satisfaction.

Additionally, based on the clinical results. we will ultimately propose an updated treatment-guided-classification that will supplement novel guidelines for implant rehabilitation combined with contemporary regenerative procedures

14. EXPECTED SCIENTIFIC OUTPUTS Publications in indexed scientific journals. Oral presentations and Posters in different local and international conventions.

15. STUDY DESIGN

16. CALENDAR February 2025 till July 2026.

• February 2025: Data Collection from the Radiology Centers.

• February till July 2025: Recall of the patients.

• September 2025 till december 2025: Statistical analysis of the data.

• March 2026: Statistical Analysis of the results+ Establishment of classification.

• May-June 2026: Thesis Writing.

• July Thesis: Thesis Submission.

  17. REFERENCES

  1. Corbella S, Taschieri S, Del Fabbro M. Long-term outcomes for the treatment of atrophic posterior maxilla: a systematic review of literature. Clin Implant Dent Relat Res [Internet]. 2015 Feb 1 [cited 2025 Jan 6];17(1):120-32. Available from: https://pubmed.ncbi.nlm.nih.gov/23656352/
  2. The International Journal of Periodontics & Restorative Dentistry. 2002.
  3. Wang.qxd. 2007.
  4. Seong WJ, Barczak M, Jung J, Basu S, Olin PS, Conrad HJ. Prevalence of sinus augmentation associated with maxillary posterior implants. J Oral Implantol [Internet].

  2013 Dec [cited 2025 Jan 6];39(6):680-8. Available from: https://pubmed.ncbi.nlm.nih.gov/21651386/ 5. Long-term evaluation of osseointegrated implants placed in sites augmented with sinus floor elevation associated with vertical ridge augmentation: a retrospective study of 38 consecutive implants with 1- to 7-year follow-up - PubMed [Internet]. [cited 2025 Jan 6].

Available from: https://pubmed.ncbi.nlm.nih.gov/15227769/ 6. Mailoa J, Fu JH, Chan HL, Khoshkam V, Li J, Wang HL. The Effect of Vertical Implant Position in Relation to Adjacent Teeth on Marginal Bone Loss in Posterior Arches: A Retrospective Study. Int J Oral Maxillofac Implants [Internet]. 2015 Jul [cited 2025 Jan 6];30(4):931-6. Available from: https://pubmed.ncbi.nlm.nih.gov/26252046/ 7. Papadimitriou D, Salari S, Gannam C, Gallucci G, Friedland B. Implant-prosthodontic classification of the edentulous jaw for treatment planning with fixed rehabilitations. Int J

Prosthodont [Internet]. 2014 Jul [cited 2024 Nov 17];27(4):320-7. Available from:

https://pubmed.ncbi.nlm.nih.gov/25010874/ 8. ABC sinus augmentation classification - PubMed [Internet]. [cited 2024 Nov 17].

Available from: https://pubmed.ncbi.nlm.nih.gov/18717377/ 9. Tolstunov L, Thai D, Arellano L. Implant-guided volumetric analysis of edentulous maxillary bone with cone-beam computerized tomography scan. Maxillary sinus pneumatization classification. Journal of Oral Implantology. 2012 Aug;38(4):377-90.

10. Teng M, Cheng Q, Liao J, Zhang X, Mo A, Liang X. Sinus Width Analysis and New Classification with Clinical Implications for Augmentation. Clin Implant Dent Relat Res [Internet]. 2016 Feb 1 [cited 2024 Nov 17];18(1):89-96. Available from: https://pubmed.ncbi.nlm.nih.gov/25041134/ 11. Eufinger H, Gellrich NC, Sandmann D, Dieckmann J. Descriptive and metric classification of jaw atrophy. An evaluation of 104 mandibles and 96 maxillae of dried skulls. Int J Oral Maxillofac Surg [Internet]. 1997 [cited 2024 Nov 17];26(1):23-8.

Available from: https://pubmed.ncbi.nlm.nih.gov/9081248/ 12. Cawood JI, Howell RA. A classification of the edentulous jaws. Int J Oral Maxillofac

Surg [Internet]. 1988 [cited 2024 Nov 17];17(4):232-6. Available from:

Inclusion Criteria:

• - Patient aged more than 18 years.
• Partially edentulous patients having an implant rehabilitation treated with a sinus lift procedure in the atrophic posterior maxilla.
• Patient with no systemic disease that contraindicate the surgical procedure as uncontrolled diabetes mellitus, bleeding disorders, recent myocardial infarction, head and neck radiation, and mental disorders.

Exclusion Criteria:

• - Fully Edentulous patients.
• Patients presenting sinus pathologies (sinusitis, thickening of the membrane).
• Patient smoking more than 20 cigarettes.
• Patient taking systemic drugs that could affect bone healing as immune suppressive drugs and bisphosphonates.
• Patient with systemic disease that contraindicate the surgical procedure as uncontrolled diabetes mellitus, bleeding disorders, recent myocardial infarction, head and neck radiation, and mental disorders.

This study consists of recruiting a number of files of patients having placed posterior implants in an atrophic posterior maxilla treated with a sinus augmentation procedure.