Clinical and Radiological Evaluation of Delayed and Early Loading of Single-Tooth Implant Placement: A 6-Month, Prospective, Randomized, Follow-up Clinical Study.

PURPOSE: The purpose of the study was to compare delayed and early loaded single-tooth implant technique.
MATERIALS AND METHODS: A randomized, prospective clinical trial was conducted to evaluate the clinical and radiological parameters of delayed and early loading of single-tooth implant placement. Fourteen male or female patients were selected randomly, who had single tooth missing in mandibular posterior region. A delayed implant placement technique was followed in these regions. A Hi-Tech implant (Life Care Implants) was performed. The patients were divided into two groups: delayed loading group and early loading group. In delayed loading groups, implants were loaded after 3 months, and in early loading groups, implants were loaded within 7 days to 2 months. Soft tissue and radiological bone loss were assessed at baseline, 3 months, and 6 months. The parameters assessed were plaque index, gingival index, probing pocket depth, thickness of peri-implant mucosa, and bone loss (radiographically).
RESULTS: The results show that there was no statistical difference in indexes taken between delayed loading and early loading groups.
CONCLUSION: In this study, after first 6 months there was no difference in success rate between delayed loading or early loading of implants. This study also showed that more bone loss occurred around delayed loading implants. So it can be concluded that early loading technique can be successfully practiced instead of delayed loading of implants.

INTRODUCTION

Modern dentistry has the goal to restore the patient to normal contour, function, comfort, esthetics, speech, and health by restoring caries tooth or replacing the missing tooth. Dental implant can fulfill most of the aforementioned goals.[1] These implants can be loaded in three types. These are immediate loading (i.e., within 1 week), early loading (i.e., between 1 week and 2 months), and delayed or conventional loading (i.e., after 2 months).[1] Studies show immediate loading of implant has higher failure rate.[2] But immediate or early loading protocols are practiced to reduce the interval between implant and prosthetic loading, which improves the patient comfort[3] and also allows the patient to return to their socioeconomic lives earlier.[4] Implant that is loaded after healing period (delayed loading) has high biologic stability, but it also has the disadvantage of prolonged treatment time.[5]

It would be worth comparing early versus delayed loading protocols to find if they have any meaningful difference. The soft and hard tissues around dental implants seem to have an important role in implant success. Monitoring marginal bone level and soft tissue around implants can help determine the success of implants.[6]

The aim of this study was to compare delayed versus early loading single-tooth implant placement technique.

MATERIALS AND METHODS

Fourteen partially edentulous patients in the age group of 20–50 years of either sex were selected from outpatient department of periodontics, JKK Nattraja Dental College, Komarapalayam, Tamil Nadu, India. These patients had single tooth missing in mandibular posterior region. These patients were divided into two groups: group 1 (delayed loading) and group 2 (early loading). Single-tooth implants were placed in these patients using either of the techniques mentioned earlier. Patients were excluded if they had any systemic conditions, insufficient bone quantity, inadequate opening of mouth, and insufficient vertical inter arch space to place the prostheses.[7] All the patients were evaluated radiographically [Figure 1]. On the basis of the analysis, the appropriate diameter and length of implants were selected. Delayed single-tooth implant placement was performed in mandibular posterior region [Figure 2]. In delayed loading group, the abutment and crown were placed after 3 months of implant placement [Figure 3]. In early loading group, the abutment and crown were placed after 7 days to 2 months of implant placement. The prosthetic crown was prepared and cemented with type II glass ionomer cement (GIC). Occlusal loading of an oral implant may result in loss of osseointegration.[8] So to avoid the risk of failure with early loaded implants, nonocclusal temporary prostheses are used as shown in Figure 4, which can be followed by occlusal loading.[9]

Figure 1

Pre-operative radiograph with stent

Figure 2

Implant placed

Figure 3

Final abutment placement

Figure 4

Cementation of prosthesis

Clinical parameters

Soft tissue around implants was assessed by a single examiner after crown cementation at baseline, 3 months, and 6 months. The parameters assessed were plaque index, gingival index, thickness of peri-implant mucosa [Figure 5], probing pocket depth (PPD) [Figure 6], and bone loss (radiographically) [Figure 7]. The significance between the groups at different time intervals was analyzed using Student t distribution.

Figure 5

Thickness of mucosa (millimeter)

Figure 6

Probing pocket depth (millimeter)

Figure 7

Radiological measurement of peri-implant bone loss

RESULTS

The results are shown in Tables 1–5 and Graphs 1–5. Statistically there was no significant difference (P > 1) between the early and delayed loaded groups at either baseline, 3 months, and 6 months when comparing the parameters like plaque index, gingival index, thickness of peri-implant mucosa, PPD, and peri-implant bone loss.

Table 1

Plaque index

Interval	Delayed loading	Early loading	Difference from baseline		t value		P value
	Mean ± SD	Mean ± SD	Delayed loading	Early loading	Delayed loading	Early loading	Delayed loading	Early loading
0 day	4.714 ± 0.371	4.986 ± 1.064
3 Months	4.686 ± 0.578	5.014 ± 1.024	0.028	0.028	0.133	0.110	0.1	0.1
6 Months	4.814 ± 0.839	4.886 ± 0.837	0.100	0.100	0.293	0.413	0.1	0.1
Interval	Delayed loading	Early loading	Difference		t value		P value		Significance
	Mean ± SD	Mean ± SD	Mean ± SD
3 Months	4.686 ± 0.578	5.014 ± 1.024	0.328 ± 0.446		0.803		0.1		NS
6 Months	4.814 ± 0.839	4.886 ± 0.837	0.072 ± 0.002		0.182		0.1		NS

NS = not significant, SD = standard deviation

Table 5

Peri-implant bone loss

Interval	Delayed loading	Early loading	Difference from baseline		t value		P value		Significance
	Mean ± SD	Mean ± SD	Delayed loading	Early loading	Delayed loading	Early loading	Delayed loading	Early loading
0 day	1.517 ± 0.435	1.179 ± 0.659
3 Months	1.764 ± 0.407	1.393 ± 0.722	0.247	0.214	3.600	3.922	0.005	0.005
6 Months	2.101 ± 0.368	1.789 ± 0.744	0.584	0.610	4.486	6.898	0.005	0.005
Interval	Delayed loading	Early loading	Difference		t value		P value		Significance
	Mean ± SD	Mean ± SD	Mean ± SD
3 Months	1.764 ± 0.407	1.393 ± 0.722	0.371 ± 0.315		1.122		0.1		NS
6 Months	2.101 ± 0.368	1.789 ± 0.744	0.312 ± 0.376		0.919		0.1		NS

NS = not significant, SD = standard deviation

Graph 1

Plaque index

Graph 5

Peri implant bone loss

DISCUSSION

A study conducted by Muthukumar et al. showed that immediate loading has higher failure rate compared to early loading.[2] Thus, early loading protocol was used in this study rather than immediate loading protocol.

Bauman et al.[10] stated that plaque is considered to be a primary etiological factor in peri-implant tissue destruction. Thus, it is appropriate to monitor oral hygiene to assess peri-implant tissue destruction through plaque indices. In this study, Table 1 showed that the plaque score was increased slightly from baseline in both the groups. But there was no statistically significant (P > 1) difference present in between mean plaque scores at 3 and 6 months. This could be because the patients maintained good oral hygiene and so there was only slight increase in plaque score. As per this study, there was no statistically significant (P > 1) difference in the mean gingival index at 3 and 6 months between the groups. But when compared to baseline, mean gingival index scores were increased in both the groups. Donati et al.[11] and Bauman et al.[12] stated that gingivitis was significantly correlated to plaque levels. So increase in mean gingival index score could be due to increased plaque score.

The study also showed that there was no statistically significant difference (P > 1) in mean thickness of peri-implant mucosa between the groups at 3 and 6 months. Both early and delayed loaded group had similar gingival biotype, i.e., 2 mm of mucosal thickness (thick biotype) at baseline, and there was slight change in it at 3 and 6 months in both groups as in accordance with the study by Jung et al.[13] He reported that 2 mm of mucosal thickness as thick biotype. A thick biotype is more fibrotic and has more vascularization, so it is more resistant to gingival recession and crestal bone loss. In thick biotype, less amount of crestal bone loss is caused when compared to thin biotype. Because the gingival biotype (thick) was the same, its effect on crestal bone loss difference between both the groups can be excluded. In this study, there was no statistically significant difference (P > 1) in mean PPD between groups at 3 and 6 months. PPD increased from the time of crown placement in both the groups, but not more than 6 mm. This was in accordance with the study conducted by Behneke et al.,[14] who stated that increase in levels of probing depth could be noted from baseline. Bauman et al.[12] stated that increase in PPD was due to undetected subgingival plaque accumulation. Another possible explanation for increased PPD could be the process of remodeling of peri-implant soft tissue for maintenance of “biological width” as stated by Koutouzis et al.[15]

The results of the study also showed that there was no significant statistical difference (P > 1) in bone loss between the groups at 3 and 6 months, but bone loss assessed using Radio Visio Graph, showed slightly more bone loss in the delayed loading group compared to the early loading group at 3 and 6 months. These results were similar to a study conducted by Guruprasada et al.[16] Meijer et al.[17] stated that increase in bone loss in delayed loading group was mainly as a result of disuse atrophy. In our study, as very minimum bone loss occurred in both the groups, no implants were lost during the 6-month study period.

CONCLUSION

From this study, the following conclusions can be arrived: (1)the success rate of single-tooth implants was the same in both the groups, (2) more bone loss can be seen in delayed loading group than in early loading group, and (3) very insignificant amount of bone loss occurred that did not affect the implant success during the initial 6 months of healing period.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Table 2

Gingival index

Interval	Delayed loading	Early loading	Difference from baseline		t value		P value		Significance
	Mean ± SD	Mean ± SD	Delayed loading	Early loading	Delayed loading	Early loading	Delayed loading	Early loading
0 day	0.857 ± 0.378	1.000 ± 0.000
3 Months	1.286 ± 0.488	1.571 ± 0.534	0.429	0.571	1.441	2.828	0.05	0.01
6 Months	1.213 ± 0.358	1.429 ± 0.534	0.429	0.429	1.441	2.121	0.05	0.025
Interval	Delayed loading	Early loading	Difference		t value		P value		Significance
	Mean ± SD	Mean ± SD	Mean ± SD
3 Months	1.286 ± 0.488	1.571 ± 0.534	0.085 ± 0.046		0.549		0.1		NS
6 Months	1.213 ± 0.358	1.429 ± 0.534	0.143 ± 0.046		1.000		0.1		NS

NS = not significant, SD = standard deviation

Table 3

Thickness of peri-implant mucosa

Interval	Delayed loading	Early loading	Difference from baseline		t value		P value		Significance
	Mean ± SD	Mean ± SD	Delayed loading	Early loading	Delayed loading	Early loading	Delayed loading	Early loading
0 day	2.286 ± 0.488	2.071 ± 0.449
3 Months	2.000 ± 0.577	1.928 ± 0.189	0.286	0.143	1.549	1.000	0.05	0.1
6 Months	1.857 ± 0.378	1.928 ± 0.189	0.429	0.143	2.121	1.000	0.025	0.1
Interval	Delayed loading	Early loading	Difference		t value		P value		Significance
	Mean ± SD	Mean ± SD	Mean ± SD
3 Months	2.000 ± 0.577	1.928 ± 0.189	0.072 ± 0.388		0.311		0.1		NS
6 Months	1.857 ± 0.378	1.928 ± 0.189	0.071 ± 0.189		0.420		0.1		NS

NS = not significant, SD = standard deviation

Table 4

Probing pocket depth

Interval	Delayed loading	Early loading	Difference from baseline		t value		P value		Significance
	Mean ± SD	Mean ± SD	Delayed loading	Early loading	Delayed loading	Early loading	Delayed loading	Early loading
0 day	2.714 ± 0.951	2.714 ± 1.704
3 Months	4.286 ± 1.113	3.571 ± 0.787	1.572	0.857	3.267	1.000	0.005	0.1
6 Months	5.000 ± 1.826	4.571 ± 0.787	2.286	1.857	3.361	3.122	0.005	0.01
Interval	Delayed loading	Early loading	Difference		t value		P value		Significance
	Mean ± SD	Mean ± SD	Mean ± SD
3 Months	4.286 ± 1.113	3.571 ± 0.787	0.715 ± 0.326		1.109		0.1		NS
6 Months	5.000 ± 1.826	4.571 ± 0.787	0.429 ± 1.039		0.701		0.1		NS

NS = not significant, SD = standard deviation