Need for the study

All-on-Four concept advocates the placement of two axially placed implants and two implants placed distally tilted for the reconstruction of edentulous arches (Calandriello et al., 2005). This rehabilitation technique registered survival rates between 95% and 97.6% for the maxilla and between 96% and 99% for the mandible 15 year follow-up (Maló P et al ,2019.The placement of implants distally tilted up to a 45-degree angle derives from the necessity of avoiding anatomical limitations such as the mandibular nerve or the maxillary sinus, allowing for an immediate function protocol (Maló Pet al 2005).

The use of tilted implants was validated previously, with Krekmanov et al., concluding that they had clinical and biologic advantages, such as improving cortical anchorage and primary stability, reducing the cantilever length, and gaining posterior support for better load distribution. Tilting may also allow the placement of a longer implant with bi-cortical anchorage , reducing the cantilever and promoting more posterior support, increasing bone to-implant contact, and reducing the stress on the alveolar crest. Although bending moments are higher for tilted implants at the abutment level, the rigidity of the prostheses and the increased supporting prosthetic base keeps stress at acceptable levels

Most studies of tilted implants have dealt with the concept of ‘‘all-on-four’’ or ‘‘all-on-six,’’ designed to avoid the mandibular canal or maxillary sinus by tilting the distal implants posteriorly. Recent studies have not found differences between the results achieved by axial and tilted implants. Also, recent studies not compared different thread designs with axially placed and tilted implants in partially edentulous arch.

Research Gap

´  Lack of Comparison of partially edentulous posterior implants with variable thread design

´   Lack of comparison of partially edentulous posterior implants with different angulation

´  Lack of Prospective clinical studies with multiple parameters, larger samples, and longer follow-up and outcome of implant supported fixed partial denture in posterior edentulous area

       Research Question

´  Is there any influence of thread design and implant angulation for immediate rehabilitation of posterior maxillary and mandibular edentulous area?

       Null Hypothesis

´  There is no influence of thread design and different implant angulation on rehabilitation of posterior maxillary and mandibular edentulous arch

´  Therefore, the purpose of this study was to compare the 2-year outcome of fixed partial prostheses in the posterior maxilla and posterior mandible with two axially placed implants and two tilted implants with different thread design.

 

 

Review of literature

 

A study was conducted to evaluate the valuate a simplified treatment concept for the rehabilitation of the atrophic maxilla using tilted implants subjected to immediate/early function. The main parameters evaluated in the study was marginal bone level and

Survival rate. The conclusion of the study was Simplified treatment procedures, reduced surgical invasion, shorter treatment time, and reduced costs constitute some of the benefits for the patient and the clinician. The main research gap identified with the study was long term follow up not done and different angulation comparison not evaluated (Roberto Calandriello et al ,2005).

 

 

A study was conducted to evaluate the use of tilted implants angled in a buccolingualdirection for restoring atrophic posterior mandibular sectors. The main parameters evaluated in the study was mean bone loss success Rate. The conclusion of the study was tilted implants provided good results for the restoration of posterior mandibles with horizontal atrophy. This cohort was too small to determine statistical differences in success rates (Marıa Penarrocha Diago,2013).

 

Another prospective study was to assess the clinical outcomes and peri implant bone level changes around tilted and axial implants supporting full-arch fixed immediate rehabilitations up to 60 months loading. The main research gap of the study was a larger number of implants and a longer follow –up are needed to confirm the above results(Luca Francetti et al,2010)

  

A Study was to compare the outcome of fixed partial prostheses in the posterior maxilla with two axially placed implants or one implant placed distally tilted and one axially placed implant following an immediate loading protocol. The main parameters evaluated was survival rate ,complications and marginal bone loss. The conclusion of the study was the use of implants placed distally tilted together with axially placed implants or two axially placed implants in the fixed partial rehabilitation of the posterior maxilla are viable treatment alternatives. The main research gap identified was prospective clinical studies with multivariable analyses, larger samples, and longer follow-up are needed to clarify the long-term outcome of fixed partial prostheses supported by implants in immediate function(Bruno et al 2013).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

       Objective of the study

 

The objective of this study is to-

 

1. Comparative evaluation of immediate placed and rehabilitated two implants in maxillary posterior edentulous arch with in straight and tilted positions of implants with variable threaded implants-  A Randomized clinical trial supported by numerical analysis.

 

 

2. Comparative evaluation of immediate placed and rehabilitated two implants in mandibular posterior edentulous arch with in straight and tilted positions of implants with variable threaded implants- A Randomized clinical trial supported by numerical analysis.

 

3.Comparative evaluation of immediately placed and restored implants in maxillary and mandibular posterior edentulous arch with variable thread design and different angulation. A prospective Randomized clinical trial.

 

Methodology

Step 1: Drawing the protocol – Ethical Committee clearance is will be obtained.

Step 2: Selecting the study participants- Eligible participants fulfilling the inclusion and exclusion criteria will be selected after obtaining the informed consent.

 

 

 

 

 

 

GROUP 1

 

 

GROUP 2

 

 

GROUP 3

 

GROUP 4

 

 

 

Step 3: Randomization- Simple randomization will be followed for both the groups. Generation of random sequences so as to which side of the patient should receive the straight active implants (Group 1) and tilted non active implants (Group 2) will be done by independent personnel.

Step 4: Intervention-The study participants will be receiving two conventional implants per arch with  diameter range of 4-4.5mm with length range of 10-11.5mm.

Step 5:

The parameters to be assessed

1.Insertion torque

2.ISQ

3.Cumulative survival rate after 6 months and 12 months and 24 months’ year

4.Radiographic Evaluation-Marginal bone loss Baseline,3 months,12 months ,24 months, post loading of the groups radiographically by a blinded evaluator with the help of CBCT data.

5.Mechanical and biological complications

Inclusion criteria –

o   Subjects with posterior edentulous maxillary and mandibular arches

o   Age group 18 -75years

o   Gender: both male and female

o   Possibility of placing at least 4 -4.5mm *10-13 mm– implants

Exclusion criteria-

§  Subjects requiring bone augmentation procedure before or during implant placement

§  Microvascular complications such as nephropathy, neuropathy and retinopathy

§  Habit of smoking, pan chewing and chronic alcoholism

§  Pre-cancerous lesions and conditions

§  medical contra indication for implant surgery

§  Severe bony defects in the implantation site

§  Poor neuromuscular control

STATISTICAL ANALYSIS

´  SPSS (Statistical Package For Social Sciences) version 20. (IBM SPASS statistics [IBM corp. released 2011] will be used to perform the statistical analysis

´  Data will be entered in the excel spread sheet.

´  Descriptive statistics of the explanatory and outcome variables will be calculated by mean, standard deviation, median and IQR (based on data distribution- Normalcy test- Shapiro wilk test) for quantitative variables, frequency and proportions for qualitative variables.

 

 

´  Inferential statistics like

Chi-square test will be applied for qualitative variables (biological and mechanical complications).

´  ANOVA/ Kruskal-wallis test (based on data distribution) will be applied to check the statistical difference of marginal bone loss, insertion torque, ISQ, among the groups with post hoc Bonferroni / Mann-whitney test (based on data distribution) for inter group comparison.

´  Repeated measures ANOVA/ Friedman test (based on data distribution) will be applied to check the statistical difference of marginal bone loss within the groups with post hoc Bonferroni/ Wilcoxon sign test for comparison between subsequent time intervals.

´  The level of significance is set at 5%

´  Any other necessary tests found appropriate will be dealt at the time of analysis based on data distribution.