Radiographic evaluation of hard tissue changes in open flap technique versus flapless technique for implant placement

Introduction

Traditionally, access for implant placement has been by elevation of full thickness mucoperiosteal flap approach.1 This approach allows the clinician to directly visualize the alveolar bone and assess bone morphology of the ridge. 2 However, this technique is relatively invasive and causes patient discomfort and marginal bone loss due to decreased supraperiosteal blood supply. 3 When flaps are reflected for the placement of implants, blood circulation from the soft tissue to the bone is disrupted, which results in poorly vascularized bone, thus promoting bone resorption during the initial healing phase almost at crestal region. 4

To overcome the limitations of elevation of mucoperiosteal flap which may lead to postoperative peri-implant tissue loss and to overcome the challenge of the soft tissue management during or after surgery, the concept of flapless implant surgery was introduced for patients with sufficient bone volume in implant recipient site. 5 In recent years, it has been noted that flapless implant surgical procedure is a predictable procedure with a high success rate if patients are properly selected and an appropriate width of bone is available for implant placement, as well as if sufficient quantity of keratinized gingiva is also present.6

Aim and Objectives

To evaluate radiographically various hard tissue changes at different time intervals around implants

Materials and Methods

A randomized, split mouth, radiograph study was conducted to evaluate the hard tissue changes in open flap technique versus flapless ṭechnique around implants at the different time interval. Screening of partially edentulous patients with at least two missing teeth was done in patients who visited the Outpatient Department, Department of Periodontics, Institute of Dental Studies & Technologies Modinagar, Uttar Pradesh.

Methodology

Pre-surgical CBCT imaging was done to assess the width and height of the implant to be placed at all the thirty edentulous sites in fourteen patients. Also the quality of bone was assessed using this CBCT scan. (Figure 1 A, B and Figure 2)

Figure 1

Preoperative site for implant placement

Figure 2

Preoperative CBCT (before implant placement)

Chart 1

Flow chart of the study protocol

Figure 3

Incision and full thickness flap elevation

Figure 4

Marking implant site with soft tissue punch

Figure 5

Osteotomy site preparation

Figure 6

Site after implant placement

Figure 7

Post-operative CBCT (immediately after implant placement)

Figure 8

Placement of prosthesis

Figure 9

CBCT with Prosthesis in place

Figure 10

Baseline (immediately after implant placement)

Figure 11

At the time of prosthetic loading

Figure 12

Three months after prosthetic loading

Result

Crestal bone level (Mesial)

Intragroup comparison

Group I (Open flap technique)

The mean Crestal Bone Level (mesial) for the implants placed in Group I was 11.20±1.66 at Baseline (BL_R) i.e. at the time of implant placement, which decreased to 10.93±1.62 at the time of prosthetic loading and further decreased to 10.69±1.61 at 3 months after prosthetic loading. (Table 1,Figure 14)

The inter-interval comparison of Crestal Bone Loss (mesial) was done using Student t- test. The Crestal Bone Loss (mesial) increased significantly from baseline till the time of prosthetic loading (0.27±0.11, p-value 0.001) and from the time of prosthetic loading to 3 months after prosthetic loading (0.24±0.11, p-value 0.001). (Table 1, Graph 2)

Group II (Flapless technique)

The mean Crestal Bone Level (mesial) for the implants placed in Group II was 10.93±1.03 at baseline i.e. at the time of implant placement, decreased to 10.87±1.12 at the time of prosthetic loading and further decreased to 10.71±1.14 at 3 months after prosthetic loading. (Table 1 1,Figure 14 )

The inter-interval comparison of Crestal Bone Loss (mesial) was done using Student t- test. The Crestal Bone Loss (mesial) increased significantly from baseline till the time of prosthetic loading (0.06±0.24, p-value 0.108) and from the time of prosthetic loading to 3 months after prosthetic loading (0.16±0.06, p-value 0.001). (Table 1, Graph 2)

Intergroup comparison

The mean Crestal Bone Level (Mesial) at baseline i.e. at the time of implant placement, at the time of prosthetic loading and from 3 months after prosthetic loading between Group I and Group II was done using unpaired t-test. There was significant difference in mean Crestal Bone Level (Mesial) at baseline (at the time of implant placement) (0.27, t-test 0.529, p-value 0.601), at the time of prosthetic loading (0.05, t-test 0.105, p-value 0.917) and 3 months after prosthetic loading (-0.03, t-test -0.052, p-value 0.959) between Group I and Group II. (Table 1, Graph 1) there was significance difference in Crestal Bone Loss (mesial) from the time of implant placement till of prosthetic loading (0.21, t value=3.083, p value= 0.005) and from the time of prosthetic loading till 3 months from prosthetic loading. (0.08, t value=2.518, p value=0.018) (Table 1 Graph 2)

Table 1

Intragroup and intergroup changes in crestal bone levels (mesial) at different time intervals

Time interval	Group I		Group II		Intergroup comparison
					Mean Difference	t-test value	p-value
	Mean	Std. Deviation	Mean	Std. Deviation
BLR	11.20	1.66	10.93	1.03	0.27	0.529	0.601
3-4 Month after BLR	10.93	1.62	10.87	1.12	0.05	0.105	0.917
6-7 Month after BLR	10.69	1.61	10.71	1.14	-0.03	-0.052	0.959
BLR-3-4 Month after BLR	0.27	0.11	0.06	0.24	0.21	3.083	0.005*
	p-value = 0.001*		p-value = 0.108
3-4 Month after BLR - 6-7 Month after BLR	0.24	0.11	0.16	0.06	0.08	2.518	0.018*
	p-value = 0.001*		p-value = 0.001*

[i] Paired t-test and Student t-test applied, *p-value significant at <0.05, # non-significant

Graph 1

Intragroup and intergroup changes in crestal bone levels (mesial) at different time intervals

Graph 2

Intragroup and intergroup changes in crestal bone loss (mesial) at different time intervals

Crestal bone level (Distal)

Intragroup comparison

Group I (Open flap technique)

The mean Crestal Bone Level (distal) was 11.20±1.66 at baseline i.e. at the time of implant placement, decreased to 10.85±1.63 at the time of prosthetic loading and further decreased to 10.59±1.64 at 3 months after prosthetic loading. (Table 2,Figure 15)

The Crestal Bone Loss (distal) increased significantly from baseline till the time of prosthetic loading (0.35±0.14, p-value 0.001) and from the time of prosthetic loading to 3 months after prosthetic loading (0.25±0.15, p-value 0.001). (Table 2, Figure 17)

Group II (Flapless technique)

The mean Crestal Bone Level (distal) was 10.93±1.03 at baseline (at the time of implant placement) which decreased to 10.81±1.18 at the time of prosthetic loading and further decreased to 10.66±1.15 at 3 months after prosthetic loading. (Table 2, Figure 16)

The Crestal Bone Loss (distal) increased significantly from baseline till the time of prosthetic loading (0.12±0.29, p-value 0.001) and from the time of prosthetic loading to 3 months after prosthetic loading (0.15±0.09, p-value 0.001). (Table 2, Figure 17)

Intergroup comparison

There was significant difference in mean Crestal Bone Level (distal) at baseline (at the time of implant placement) (0.27, t-test 0.529, p-value 0.601), at the time of prosthetic loading (0.03, t-test -0.064, p-value 0.949) and 3 months after prosthetic loading (-0.07, t-test -0.129, p-value 0.898) between Group I and Group II. There was significant difference in Crestal Bone Loss (distal) from the time of implant placement till the time of prosthetic loading (0.23, t value=2.797, pvalue=0.009) and from the time of prosthetic loading to 3 months after prosthetic loading (0.10; t value=2.250; pvalue=0.032) (Table 2, Figure 17)

Table 2

Intragroup and intergroup changes in crestal bone levels (distal) at different time intervals

Time interval	Group I		Group II		Intergroup comparison
					Mean Difference	t-test value	p-value
	Mean	Std. Deviation	Mean	Std. Deviation
BLR	11.20	1.66	10.93	1.03	0.27	0.529	0.601
3-4 Month after BLR	10.85	1.63	10.81	1.18	0.03	0.064	0.949
6-7 Month after BLR	10.59	1.64	10.66	1.15	-0.07	-0.129	0.898
BLR-3-4 Month after BLR	0.35	0.14	0.12	0.29	0.23	2.797	0.009*
	p-value = 0.001*		p-value = 0.406
3-4 Month after BLR - 6-7 Month after BLR	0.25	0.15	0.15	0.09	0.10	2.250	0.032*
	p-value = 0.001*		p-value = 0.001*

[i] Paired t-test and Student t-test applied, *p-value significant at <0.05, # non-significant

Graph 3

Intragroup and intergroup changes in crestal bone levels (distal) at different time intervals

Graph 4

Intragroup and intergroup changes in crestal bone loss (distal) at different time interval

Discussion

In our study, in both the groups, the mean crestal bone loss (mesial and distal) from the time of implant placement till the time of prosthetic loading was less as compared to the crestal bone loss from the time of prosthetic loading till the time of 3 months post prosthetic loading indicating that physiologic remodelling does take place during first 3 months of implant placement and thereafter functional loading may lead to increase crestal bone loss. According to Hermann JS et al 7 many procedural and biomechanical factors like implant design, micro movement and second stage surgery may lead to disruption of junctional epithelium leading to more crestal bone resorption after loading.

In intergroup comparison, there was no significant difference in mean crestal bone loss (mesial) and (distal) at from the time of implant placement till the time of prosthetic loading and from the time of prosthetic loading to 3 months after prosthetic loading. These results were in accordance with the previous research by Sunitha and Sapthagiri 8 who observed that the mean bone loss was greater with the open flap group as compared with the flapless group.

Shibu et al 9 noted that flapless implant surgery has improved crestal bone levels and osseointegration compared with the conventional technique. A study by Abdul-Saheb et al 10 concluded that with flapless implant placement there is less bone level reduction when compared with the flap technique. 11 The findings of the present study demonstrate that the mean bone loss was less after flapless implant surgery and that no implants failed to osseointegrate. 12 The lower rate of crestal bone loss in the present study may be due to use of a tissue punch that was narrower than the implant itself.13 Another explanation for the high success rate may be that when flaps are not reflected, the periosteum is preserved, which may help to optimize the healing of the periimplant tissue. 14 Therefore, the flapless technique can be considered as a better treatment approach for the placement of implants. 15

Conclusion

It can be concluded that flapless procedure may be considered as a better treatment option as compared to implant placed with open flap technique in terms of minimal pain, inflammation and less crestal bone loss associated with flapless technique than open flap technique.16 Proper evaluation of bone type, height and width of the residual ridge, amount of available keratinized tissue and clinical acumen of the clinician determines the success of flapless procedure. 17

Source of Funding

None.

Conflict of Interest

None.