ORIGINAL RESEARCH

https://doi.org/10.5005/jp-journals-10019-1427
International Journal of Prosthodontics and Restorative Dentistry
Volume 13 | Issue 4 | Year 2023

Effect of Flap and Flapless Implant Surgical Techniques on Tissues around Dental Implants: An In Vivo Study

Sanjay Lagdive¹, Rupal J Shah², Nilesh B Gadiya³, Nilesh Patel⁴, Ami Panchal⁵, Real P Brahmbhatt⁶

^1–6Department of Prosthodontics & Crown & Bridge, Government Dental College & Hospital, Ahmedabad, Gujarat, India

Corresponding Author: Nilesh B Gadiya, Department of Prosthodontics and Crown & Bridge, Government Dental College & Hospital, Ahmedabad, Gujarat, India, Phone: +91 9512749274, e-mail: nbgadiya647@gmail.com

Received: 31 August 2023; Accepted: 30 November 2023; Published on: 30 December 2023

ABSTRACT

Purpose: To compare and evaluate the effect of flap and flapless implant placement on peri-implant hard and soft tissue health.

Materials and methods: A total of 40 implant sites in the mandibular molar region in 40 patients were chosen, with 20 for the conventional flap procedure and 20 for the flapless procedure. The parameters selected were radiographic marginal bone loss, implant mobility, modified plaque index, modified bleeding index (MBI), and probing depth measurement at the time of loading (baseline), 3, 6, and 12 months after loading. Descriptive statistics and repeated measures of analysis of variance (ANOVA) tests were done to evaluate significant differences at different time intervals.

Results: The flapped technique showed higher mesial and distal crestal bone loss at 3, 6, and 12 months (p = 0.001). The bleeding index was also higher in flapped implants at 3, 6, and 12 months (p = 0.002). Probing depth was significant for flapped implants on all sides at different intervals (p-values ranging from 0.001 to 0.024). The plaque index was not significant. The mobility index was 0 ± 0 for both techniques after 12 months, with significant p-values of 0.025 and 0.001 for flapless and flapped techniques, respectively.

Conclusion: Marginal bone loss is lower in flapless implant surgical placement. No clinically significant difference was observed between flap and flapless surgery in terms of implant mobility and plaque index. The probing depth and bleeding index around implants placed using the flap technique showed significant changes compared to the flapless technique.

How to cite this article: Lagdive S, Shah RJ, Gadiya NB, et al. Effect of Flap and Flapless Implant Surgical Techniques on Tissues around Dental Implants: An In Vivo Study. Int J Prosthodont Restor Dent 2023;13(4):222–227.

Source of support: Nil

Conflict of interest: None

Keywords: Dental implant, Flapped implant surgical placement, Flapless implant surgical placement, Marginal bone loss, Modified plaque index

INTRODUCTION

Implant dentistry has advanced from a functional treatment to a discipline focused on esthetics. As a result, clinicians have adopted techniques to reduce treatment time, such as immediate implant placement, immediate loading, and flapless surgical procedures.¹ When placing implants, a flap is typically elevated to expose the area and identify key anatomical landmarks. This allows for the reduction of knife-edge ridges to develop a crystal table for small-diameter implants. This method results in minimal loss of keratinized tissue since the flap is replaced and sutured after surgery.²

However, there is a slight bone loss associated with raising a surgical mucoperiosteal flap for dental implants, which can lead to scarring and other complications in the esthetic zone.³^,⁴ To overcome this, the flapless surgical approach was introduced by Ledermann et al.⁵ This approach offers advantages over traditional techniques, such as decreased surgical time, maintenance of both soft and hard tissues, decreased bleeding and pain, faster recovery, and improved patient comfort.⁶

Many studies have compared the clinical efficacy of flap and flapless techniques but had some limitations, like they didn’t use digital radiographic methods and did not compare soft and hard tissue simultaneously.⁷–¹⁰

The purpose of this study was to compare and evaluate the effects of flap and flapless implant placement on peri-implant hard and soft tissues. The null hypothesis (H0) posits that there would be statistically insignificant difference in the clinical outcome between the flap and flapless techniques.

MATERIALS AND METHODS

Study Design

The study conducted was a retrospective cohort study that selected patients from the outpatient Prosthodontics Department of the Government Dental College and Hospital, Ahmedabad. Ethical clearance for the study was obtained with clearance number IEC GDCH/PROS.4/2021 on 24^th March 2021. The recruitment for the study was done between April and July 2021. The study involved observations over the course of 1 year.

Sample Size Estimation

The sample size calculation was calculated as 40. It was done using G*Power software with an effect size of 0.6, with 5% type I error and 90% power. Samples were randomly divided into two groups using a coin flip method. The double-blind study ensured allocation concealment was done by the sequentially numbered, opaque, sealed envelope (SNOSE) method.

In the mandibular molar region, a total of 40 implant sites were selected in 40 patients. Out of these, 20 patients underwent the conventional flap procedure, and the remaining 20 received the flapless procedure. Prior to the initiation of the study, all subjects were made aware of the procedure, and its associated risks and written consent was diligently obtained.

Inclusion and Exclusion Criteria

To be eligible for the study, patients should be 18 years of age or older, present with partial edentulism requiring a minimum of one implant, exhibit missing lower posterior teeth, systemically healthy with good oral hygiene, and possess enough available bone of at least D2 or D3 quality. Furthermore, they should be willing and capable of providing informed consent. Patients having a history of diabetes or any other debilitating systemic disease, which required ridge augmentation following implant placement, were excluded. Patients with a history of parafunctional habits such as bruxism or clenching, who had an anterior deep bite or unstable occlusion, or who had a history of smoking were also excluded from the study.

Presurgical Preparation

After the initial examination and treatment planning, the chosen subjects underwent phase I therapy. Patients were given detailed instructions regarding proper self-performed plaque control measures.

Each patient underwent radiographic examinations using sectional cone beam computed tomography of the area of interest. If needed, conventional periapical radiographs and orthopantomogram were also used. Implant sizes were selected based on these readings. Additionally, an Alginate impression (Pyrax®, Mumbai, India) of both the upper and lower arch was made, and study casts were prepared for each patient. Customized stents were created for implant placement on the study casts using self-cure acrylic resin.

Surgical Protocol

Before surgery, each patient received a preprocedural rinse using 0.2% chlorhexidine gluconate mouthwash to lower the chance of bacteremia. For the flapless technique, the proposed implant site’s soft tissue was punched using soft tissue punches (Dentium, Seoul, South Korea) of diameters based on the implant size (4.5 width and 10 mm length) (Dentium, Seoul, South Korea). This procedure was under using local anesthesia (2% lidocaine 1:100,000 epinephrine).

In the conventional technique, the full-thickness flap after the envelope incision was elevated for complete exposure of the bone site. The drilling procedure followed the guidelines of the implant manufacturer (Dentium, Seoul, South Korea). All implants were placed equicrestally. Following the placement of the implant, periapical radiographs were taken using the paralleling technique to ensure proper angulation and equicrestal placement. Healing abutments were immediately connected to the fixtures to expose the coronal aspect of the abutment to the oral cavity.

Clinical and Radiographic Examination

Peri-implant Crestal Bone Loss

Radiographs were taken during prosthetic loading at baseline, and patients were later followed up at 3, 6, and 12 months. To ensure consistency, a silicone putty bite index (AFFINIS, Coltene, Mumbai, India) and an extension cone paralleling film holder (Rinn XCP, Dentsply Sirona, Charlotte, North Carolina, United States of America) was used with a long cone paralleling technique (Fig. 1) for radiographs. Intraoral photosensitive plate was used with paralleling technique through a film holder for radiographic evaluation.¹¹ Analysis was performed using the computer software program (Cruxcan, CRUXELL Corp., Daejeon, South Korea). The coronal aspect of the implant surface was taken as a reference, and a line perpendicular line was placed on the mesial and distal side aspect implant to the site with a first implant-to-bone contact (Fig. 2). A single investigator observed the radiographs under the same light conditions. The average of three readings was taken on both the mesial and distal sides.¹¹

Fig. 1: Rin XCP used for standardization of radiograph

Fig. 2: Digital length measurement tool used to determine crestal bone loss

Implant Mobility Index

The mobility of the implant was measured by the clinical implant mobility scale by Misch et al.¹² The mobility of the implant, two rigid instruments were used to apply a labiolingual force of approximately 500 gm at the time of loading, that is baseline. Patients were then recalled for follow-up visits at 3, 6, and 12 months after the procedure.

Plaque Index

To assess peri-implant health, a plaque index by Mombelli et al.¹³ was used. This involved a numerical scale ranging from 0 to 3, which depended on the amount of visible plaque present or by running a probe (Williams Colorvue™ Probe Kit, Hu-Friedy, Chicago, United States) over the implant surface. Follow-up appointments were scheduled for patients at 3, 6, and 12 months after implant loading.¹⁴

Modified Bleeding Index

The modified bleeding index (MBI) developed by Mombelli et al.¹³ was used. The measurements were taken 0, 3, 6, and 12 months after implant loading.

Probing Depth Measurements

Probing depth measurements were taken at 0, 3, 6, and 12 months after implant loading. The implants’ buccal, lingual, mesial, and distal surfaces were measured using a plastic periodontal probe kit with a probing force of 0.2 N. The average of these measurements was considered.¹³

Postsurgical Protocol

After surgery, patients were put on a strict maintenance schedule, and recall appointments were scheduled to record their parameters and oral prophylaxis. A clinical evaluation was conducted every 4 weeks to thoroughly analyze the peri-implant soft tissues and check for any signs of inflammation or infection.

Statistical Analysis

Data was analyzed using the Statistical Package for the Social Sciences (SPSS) (IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 26.0. Armonk, New York: IBM Corp.), and the level of significance was set at p < 0.05. Descriptive statistics and repeated measures of analysis of variance (ANOVA) tests were done to evaluate significant differences at different time intervals.

RESULTS

The study found significant differences in bone loss between flapless and flapped implant surgery (Table 1). Flapless implants had less mesial (0.09 mm at baseline, 0.44 mm in 12 months) and distal crestal bone loss (0.07 mm at baseline, 0.43 mm in 12 months). Flapped implants had more mesial (0.12 mm at baseline, 0.66 mm in 12 months) and distal crestal bone loss (0.09 mm at baseline, 0.63 mm in 12 months).

**Table 1:** Repeated measure ANOVA comparing mean value at different time intervals for each category
Category	Site	Technique	Mean ± standard deviation					p-value
Category	Site	Technique	Baseline	3 months	6 months	12 months	Total	p-value
_{Crestal bone loss}	_Mesial	_Flapless	_{0.09 ± 0.08}	_{0.17 ± 0.1}	_{0.26 ± 0.13}	_{0.44 ± 0.1}	_{0.24 ± 0.17}	_0.001*
	_Mesial	_Flap	_{0.12 ± 0.08}	_{0.29 ± 0.12}	_{0.48 ± 0.11}	_{0.66 ± 0.12}	_{0.39 ± 0.23}	_0.001*
	_Distal	_Flapless	_{0.07 ± 0.07}	_{0.17 ± 0.11}	_{0.24 ± 0.1}	_{0.43 ± 0.13}	_{0.23 ± 0.17}	_0.001*
	_Distal	_Flap	_{0.09 ± 0.07}	_{0.28 ± 0.12}	_{0.46 ± 0.13}	_{0.63 ± 0.1}	_{0.36 ± 0.23}	_0.001*
_{Mobility index}		_Flapless	_{0 ± 0}	_{0 ± 0}	_{0 ± 0}	_{0 ± 0}	_{0 ± 0}	_0.025*
_{Mobility index}		_Flap	_{0 ± 0}	_{0 ± 0}	_{0 ± 0}	_{0 ± 0}	_{0 ± 0}	_0.001*
_{Plaque index}	_Mesial	_Flapless	_{0.15 ± 0.37}	_{0.2 ± 0.41}	_{0.2 ± 0.41}	_{0.45 ± 0.51}	_{0.25 ± 0.44}	_0.118
	_Mesial	_Flap	_{0.35 ± 0.49}	_{0.35 ± 0.49}	_{0.35 ± 0.49}	_{0.45 ± 0.51}	_{0.37 ± 0.49}	_0.893
	_Distal	_Flapless	_{0.3 ± 0.47}	_{0.4 ± 0.5}	_{0.55 ± 0.51}	_{0.55 ± 0.51}	_{0.45 ± 0.5}	_0.304
	_Distal	_Flap	_{0.4 ± 0.5}	_{0.45 ± 0.51}	_{0.6 ± 0.5}	_{0.65 ± 0.49}	_{0.53 ± 0.5}	_0.343
	_Buccal	_Flapless	_{0.15 ± 0.37}	_{0.3 ± 0.47}	_{0.35 ± 0.49}	_{0.35 ± 0.49}	_{0.29 ± 0.46}	_0.453
	_Buccal	_Flap	_{0.25 ± 0.44}	_{0.35 ± 0.49}	_{0.5 ± 0.51}	_{0.5 ± 0.51}	_{0.4 ± 0.49}	_0.299
	_Labial	_Flapless	_{0.35 ± 0.49}	_{0.4 ± 0.5}	_{0.45 ± 0.51}	_{0.45 ± 0.51}	_{0.41 ± 0.5}	_0.904
	_Labial	_Flap	_{0.35 ± 0.49}	_{0.4 ± 0.5}	_{0.5 ± 0.51}	_{0.6 ± 0.5}	_{0.46 ± 0.5}	_0.409
_{Bleeding index}		_Flapless	_{0 ± 0}	_{0 ± 0}	_{0 ± 1}	_{1 ± 1}	_{0 ± 1}	_0.002*
_{Bleeding index}		_Flap	_{0 ± 0}	_{0 ± 1}	_{1 ± 1}	_{1 ± 1}	_{1 ± 1}	_0.001*
_{Probing depth}	_Mesial	_Flapless	_{1 ± 0.32}	_{1 ± 0.32}	_{1 ± 0.32}	_{1 ± 0.32}	_{1 ± 0.32}	₁
	_Mesial	_Flap	_{1.1 ± 0.45}	_{1.35 ± 0.49}	_{1.45 ± 0.69}	_{1.65 ± 0.59}	_{1.39 ± 0.58}	_0.024*
	_Distal	_Flapless	_{1 ± 0.46}	_{1.1 ± 0.55}	_{1.25 ± 0.44}	_{1.25 ± 0.44}	_{1.15 ± 0.48}	_0.465
	_Distal	_Flap	_{1.1 ± 0.55}	_{1.4 ± 0.5}	_{1.6 ± 0.6}	_{2.05 ± 0.39}	_{1.54 ± 0.62}	_0.001*
	_Buccal	_Flapless	_{1.1 ± 0.45}	_{1.15 ± 0.49}	_{1.15 ± 0.49}	_{1.15 ± 0.49}	_{1.14 ± 0.47}	_0.983
	_Buccal	_Flap	_{1.1 ± 0.45}	_{1.2 ± 0.52}	_{1.35 ± 0.49}	_{1.9 ± 0.85}	_{1.39 ± 0.67}	_0.001*
	_Labial	_Flapless	_{0.95 ± 0.22}	_{1.05 ± 0.39}	_{1.05 ± 0.39}	_{1.05 ± 0.39}	_{1.02 ± 0.35}	_0.903
	_Labial	_Flap	_{0.95 ± 0.51}	_{1.15 ± 0.67}	_{1.25 ± 0.44}	_{1.5 ± 0.61}	_{1.21 ± 0.59}	_0.025*

*p < 0.05 is significant

Both flapless implant placement (p = 0.025) and flapped surgery (p = 0.001) had a mobility index of 0 ± 0 after 12 months (Table 1). The plaque index for mesial, distal, buccal, and lingual sides of implants placed with flapless and flapped techniques was not significant at different intervals (0, 3, 6, and 12 months) (Table 1).

The bleeding index for flapless implant at 0, 3, 6, and 12 months was 0 ± 0, 0 ± 0, 0 ± 1, and 1 ± 1 and it was significant (p = 0.002). The flapped implant had a bleeding index of 0 ± 0, 0 ± 1, 1 ± 1, and 1 ± 1; the value is significant (p = 0.002) (Table 1).

Probing depth around implants that were placed using the flapless technique did not show any significant changes at 3, 6, and 12 months. However, the depth of probing around implants placed using the flap technique showed significant changes after 3, 6, and 12 months (Table 1).

Crestal bone loss and probing depth comparing flap and flapless technique at specific implant sites were presented in Table 2. Bleeding and plaque index comparing flap and flapless technique at specific implant sites was presented in Table 3.

**Table 2:** Mean crestal bone loss and probing depth at each implant site
Site	Technique	Crestal bone loss		Probing depth
Site	Technique	Mesial	Distal	Mesial	Distal	Buccal	Labial
36	Flapless (N = 8)	0.26 ± 0.15	0.24 ± 0.14	0.87 ± 0.34	1.22 ± 0.42	1.22 ± 0.42	1.09 ± 0.3
36	Flap (N = 6)	0.4 ± 0.24	0.4 ± 0.25	1.38 ± 0.49	1.33 ± 0.64	1.12 ± 0.61	1 ± 0.42
37	Flapless (N = 0)	–	–	–	–	–	–
37	Flap (N = 5)	0.39 ± 0.24	0.34 ± 0.2	1.4 ± 0.5	1.5 ± 0.51	1.55 ± 0.69	1.25 ± 0.72
46	Flapless (N = 7)	0.21 ± 0.17	0.23 ± 0.19	1.14 ± 0.36	1.11 ± 0.63	1.14 ± 0.36	1 ± 0
46	Flap (N = 4)	0.39 ± 0.23	0.39 ± 0.23	1.38 ± 0.5	1.94 ± 0.68	1.56 ± 0.63	1.5 ± 0.52
47	Flapless (N = 5)	0.25 ± 0.18	0.19 ± 0.17	1 ± 0	1.1 ± 0.31	1 ± 0.65	0.95 ± 0.6
47	Flap (N = 5)	0.36 ± 0.22	0.34 ± 0.23	1.4 ± 0.82	1.5 ± 0.51	1.4 ± 0.68	1.2 ± 0.62
Total	Flapless (N = 20)	0.24 ± 0.17	0.23 ± 0.17	1 ± 0.32	1.15 ± 0.48	1.14 ± 0.47	1.02 ± 0.35
Total	Flap (N = 20)	0.39 ± 0.23	0.36 ± 0.23	1.39 ± 0.58	1.54 ± 0.62	1.39 ± 0.67	1.21 ± 0.59

**Table 3:** Mean plaque and bleeding index at each implant site
Site	Technique	Plaque index				Bleeding index
Site	Technique	Mesial	Distal	Buccal	Labial	Bleeding index
36	Flapless (N = 8)	0.25 ± 0.44	0.31 ± 0.47	0.25 ± 0.44	0.59 ± 0.5	0 ± 1
36	Flap (N = 6)	0.54 ± 0.51	0.46 ± 0.51	0.29 ± 0.46	0.38 ± 0.49	1 ± 1
37	Flapless (N = 0)	–	–	–	–	–
37	Flap (N = 5)	0.05 ± 0.22	0.6 ± 0.5	0.65 ± 0.49	0.25 ± 0.44	0 ± 1
46	Flapless (N = 7)	0.04 ± 0.19	0.61 ± 0.5	0.29 ± 0.46	0.36 ± 0.49	0 ± 0
46	Flap (N = 4)	0.75 ± 0.45	0.44 ± 0.51	0 ± 0	1 ± 0	1 ± 0
47	Flapless (N = 5)	0.55 ± 0.51	0.45 ± 0.51	0.35 ± 0.49	0.2 ± 0.41	0 ± 1
47	Flap (N = 5)	0.2 ± 0.41	0.6 ± 0.5	0.6 ± 0.5	0.35 ± 0.49	0 ± 0
Total	Flapless (N = 20)	0.25 ± 0.44	0.45 ± 0.5	0.29 ± 0.46	0.41 ± 0.5	0 ± 1
Total	Flap (N = 20)	0.37 ± 0.49	0.53 ± 0.5	0.4 ± 0.49	0.46 ± 0.5	1 ± 1

DISCUSSION

Implant placement can be done by the conventional technique, by raising a mucoperiosteal flap and placing the implant. However, this technique has several disadvantages, such as increased bone resorption during the initial healing phase, postoperative scarring, etc.¹^,¹⁵^,¹⁶

In contrast to this, flapless implant surgery has numerous advantages, such as preservation of blood circulation because, in flapless implant placement, the elevation of the flap is not done.¹⁷ Maintenance of soft tissue architecture as only a small tissue punch is done to access the alveolar bone.¹⁸ Maintenance of hard tissue volume at the site because the flap is not elevated, and the blood supply to the underlying alveolar bone is not hampered.¹⁵ Decreased surgical time for the procedure and no requirement of sutures. These will ultimately lead to better patient comfort and increased recuperation and allow the patient to perform routine oral hygiene procedures after the implant placement.¹⁰

The present study aimed to determine the effects of flapped vs. flapless implant placement technique on the hard and soft tissue profiles around dental implants after prosthetic loading. Albrektsson success criteria,¹⁹ had reported that the average marginal bone loss of implant should be <1.5 mm in 1st year of function. The flapless implant surgery reported marginal bone loss ranging from 0.4 to 1.2 mm 1st year.²⁰

In the present study, 40 implant sites in the mandibular molar region in 40 patients were chosen, with 20 for the conventional flap procedure and 20 for the flapless procedure. Hard and soft tissue changes were compared around dental implants for 1 year. The crestal bone loss with flapless implant placement was lower at the end of 12 months compared to flapped implant surgery. Many previous studies had a similar conclusion.¹^,²¹–²⁸

The reason for the increased success rate may be in the flapless procedure; there was the preservation of the periosteum, which may help in better healing of the peri-implant tissue. Another reason may be that there was effective plaque control in the flapless procedure, which caused less crestal bone loss in the present study. There is also immediate cleaning possible around implants in flapless procedures.¹ However, many studies got inconclusive results and found no clinically significant differences between the two techniques.⁶^,¹⁶^,²⁷–²⁹

The present study could not find any clinically significant difference in soft tissue health between the two techniques in terms of plaque index. Similar results were found by Lee et al.³⁰ and Oh et al.³¹ This may be explained based on the maintenance of good healing conditions in the soft tissue adjacent to flapless implants and the maintenance of proper oral hygiene by the patients, contributing to the resulting stable soft tissue profiles.¹⁰^,¹⁵^,¹⁷^,¹⁸

In the present study, the probing depth and bleeding index around implants placed using the flap technique showed significant changes compared to the flapless technique. In the present study, in the 6 months observation period, no implant failure, implant mobility, and peri-implant inflammation or pain have been reported. Interestingly, a study by Wittwer et al.,³² associated only two implant failures out of 78 implants with the transmucosal flapless procedure rather than following the navigated surgical protocol. They noted that this technique might not be suitable for all bone morphologies, that is, uneven bone surfaces, which may lead to bone fenestration.

The clinical outcomes, specifically in terms of marginal bone loss, probing depth, and bleeding index, around implants placed using the flap technique exhibited a clinically significant difference compared to the flapless technique. As a result of these findings, the H0 is rejected.

The alternate hypothesis asserts that there is a statistically significant difference in the clinical outcomes, encompassing marginal bone loss, probing depth, and bleeding index, around implants placed using the flap technique in comparison to the flapless technique.

This study has some limitations that need to be considered. The sample size in this study was limited, which may impact the generalizability of our findings to a broader patient population. Additionally, the study focused on a specific implant site. Moreover, the duration of observation was relatively short, spanning only 1 year. To address these limitations and provide more comprehensive insights, future research should aim for long-term studies with a larger and more diverse patient population. These studies can help confirm and build upon the present study’s initial findings, offering a more robust understanding of the factors influencing outcomes in different patient groups and over extended time periods.

CONCLUSION

From this study, it can be concluded that marginal bone loss is lower in flapless implant surgical placement. No clinically significant difference was observed between flap and flapless surgery in terms of implant mobility and plaque index. The probing depth and bleeding index around implants placed using the flap technique showed significant changes compared to the flapless technique.

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