Pink esthetic and radiological scores around immediate implants placed in the esthetic zone - Socket-Shield Technique versus Immediate Conventional Technique: A Pilot Study.

OBJECTIVE: It is irrefutable that the extraction of teeth inextricably results in definitive changes in the surrounding hard and soft tissues. Recently, Socket-Shield Technique (SST) has been used to keep the buccal two-third of the root intact in the socket. This buccal shield further preserves the periodontium-bundle bone complex and hence preserves the buccal hard and soft tissue. The purpose of the study was to do a statistical comparative analysis of two different types of flapless and graftless techniques using the esthetic (Pink Esthetic Index) and radiological parameters.
MATERIALS AND METHODS: A total of thirty nonrestorable tooth/root stumps (vital or nonvital) were selected and randomly allocated to two different groups: control group with immediate conventional implant placement (without SST) (Group C, n = 15) and test group with immediate implant placement using SST (Group S, n = 15). All of the sites received immediate chairside temporaries. All implants were restored either with screw- or cement-retained prostheses 4 months postoperative. Each control and test group was analyzed at two different durations: 15 days after placement of provisional and 15 days after placement of definitive prosthesis. Five parameters of Pink Esthetic Score (PES) were used for esthetic analysis, and digital periapical radiographs were used for radiographic analysis.
RESULTS: Within the time frame of the study (15 days postplacement of definitive prosthesis), a statistically significant difference (p < 0.05) was observed between PES of the two techniques. Test group S (mean = 9.07) showed better scores than control group C (mean = 6.87). It was observed that buccal bone was maintained in all the cases of test group S while there was loss of buccal bone in almost all the cases of control group C.
CONCLUSION: Within the limitations of this short-term pilot study, better soft-tissue parameters were observed with SST as compared to a conventional graftless technique whenever a restoration on immediate implant placement is considered. Copyright:

INTRODUCTION

An acceptable implant restoration is one that bears a resemblance to the natural tooth. It is crucial for the successful outcome and satisfaction of the patient and the clinician. Prosthetic rehabilitation of a missing tooth aims to achieve the balance between “the pink zone” and “the white zone,” especially in the esthetic areas. One of the sequelae of the extraction of the tooth is loss of buccal bone.[12] The reason behind the resorption of buccal bone is the loss of the periodontal ligament (PDL) which is one of the sources of blood supply to the bundle bone and the outer cortex. The buccal bone reduction further causes vertical and horizontal bone loss of the alveolar ridge and usually continues throughout life.[34] A variety of preventive procedures like extraction socket grafting techniques, and postridge collapse procedures, such as bone augmentation, soft-tissue augmentation, or a combination of these, have been used to compensate for this loss.[5]

To minimize the postextraction bone loss and to reduce overall procedure and restoration time, immediate implant placement procedures have been introduced. Although survival rate of immediate implant placements is similar to delayed implants; it is not successful in preventing the postextraction loss of vertical and horizontal buccal bone and often results in flattening of the interproximal bony scallop.[6] This results in unesthetic black triangles between restored teeth leading to the complex rehabilitation process.[7] The buccal bone recession and ridge collapse can lead to an esthetic compromise and can be disastrous in cases with high esthetic demand like the anterior maxillary teeth in young female patients, patients with high lip lines and/or thin gingival biotype or multiple mutilated nonrestorable teeth.[2]

Recently, the socket-shield technique (SST) has emerged as an alternative treatment modality to replace the hopeless teeth in the esthetic zone.[89] The objective of SST is to longitudinally section the root of the nonrestorable tooth and extract only the palatal part so that the buccal section remains intact in the socket with its attached PDL and buccal cortical plate. The rationale behind this procedure is to preserve the bundle bone by preserving the PDL. The remaining undamaged and immobile buccal root fragment prevents the expected postextraction socket remodeling and supports the buccal/facial hard and soft tissues.[10] SST is quoted by various other names as partial extraction therapy, root membrane technique, and partial root retention.[1011121314]

The aim of this study was to analyze and compare the Pink Esthetic Scores (PES) and radiological scores after the placement of provisional and definitive prosthesis using two flapless and graftless immediate implant techniques: conventional versus SST [Table 1].[151617]

Table 1

Pink Esthetic Score (PES) Index [151617]

Parameter	Score = 0	Score = 1	Score = 2
1. Mesial papilla (MP)	Absent	Incomplete	Complete
2. Distal papilla (DP)	Absent	Incomplete	Complete
3. Curvature of facial mucosa (CFM)	Major Discrepancy	Minor Discrepancy	No Discrepancy
4. Level of facial mucosa (LFM)	Major Discrepancy	Minor Discrepancy	No Discrepancy
5. Root convexity (RC)	Major Discrepancy	Minor Discrepancy	No Discrepancy

PES=MP + DP+ CFM + LFM + RC, Maximum PES=10. PES - Pink Esthetic Score

MATERIALS AND METHODS

Twenty patients (14 males and 6 females; mean age: 37 years) who had vital or nonvital nonrestorable tooth/root stumps and who reported to Department of Prosthodontics and Crown & Bridge, School of Dental Sciences, Sharda University, Greater Noida, India, between January 2017 and March 2018 were selected according to a predefined criterion. The study was approved by the Human Ethical Committee of the institution. The procedure was explained to all the patients in detail, and informed consent was obtained in writing from them. Thirty sites involving replacement of failing/fractured maxillary anterior teeth were used (tooth no. #13, #12, #11, #21, #22, and #23) for the study, and it included both root canal treatment treated and vital nonrestorable teeth/root stumps. Only firm teeth/root stumps with no buccal bone loss were selected for the study [Figures 1 and 2]. The exclusion criteria were all absolute and relative contraindications to implant surgery, sites with a multirooted tooth, perforated buccal bone, root stumps/tooth with mobility, periodontal loss, and the internal and external resorption of the involved tooth.

Figure 1

Preoperative clinical photograph (Group S)

Figure 2

Preoperative situation (Group C)

The sites were randomly segregated into two groups by flipping a coin method. The control group was Group C which received conventional immediate implant placement (without SST) (n = 15), and the test group was Group S that received immediate implant placement along with SST (n = 15). The null hypothesis (H0) was that no difference in PES scores will be observed between the control and test groups 15 days after the provisional and definitive prosthesis while the alternative hypothesis (Ha) was that a difference in PES scores will be observed between the control group (Group C) and the test group (Group S).

Clinical procedure

After the local anesthesia was administered, the tooth was sectioned till the gingival level. Using a long root resection bur, it was then divided into two parts: buccal and palatal. This tends to keep the buccal half of the root intact and undamaged. The PDL on the palatal aspect of root was carefully severed using periotomes. In all the sites in Group S, palatal section of the root was then gently extracted without mobilizing the buccal root section. Apex was removed along with the palatal part [Figure 3a and b]. The length of the shield was kept approximately two-third of the root length. The coronal end of the shield was kept at the level of the alveolar crest. The shield was carefully shaped, such that the shield width was in the range of 1.5–2 mm. A S-shaped bevel was prepared on the socket facing side of the coronal part of the shield. This provides adequate space for the prosthetic components.[181920]

Figure 3

(a) Atraumatic extraction of palatal half of root stump (Group S); (b) Palatal half of root stump (Group S)

The curettage of the extraction socket was then done thoroughly to remove any granulation tissue present, and the buccal root shield was checked for immobility. In all the sites in Group C, the whole of the root was atraumatically extracted. No flap was raised and no graft was inserted in any of the sites involved [Figures 3a and 4].

Figure 4

Atraumatic extraction of complete root (Group C)

The implant site was prepared according to the drilling sequence of the implant system. Lance drill was used first to engage the palatal aspect of the socket. After osteotomy, a 3.5-mm diameter implant (Megagen AnyRidge) with predetermined length was placed [Figures 5 and 6].

Figure 5

Implant placed palatal to the shield (Group S)

Figure 6

Implant placed (Group C)

Immediately after the implant placement, a chairside screw-retained temporary crown was fabricated using a titanium cylinder and bis-acryl composite resin (Luxatemp Star) [Figures 7a, b and 8]. A meticulous occlusal check was performed on the provisional restoration to ensure nonfunctional loading. Postsurgical instructions were explained to the patient. Chlorhexidine 0.12% oral rinses were prescribed, and after 15 days, the patient was recalled for postoperative evaluation. The site was clinically and radiographically evaluated. The patient was then recalled 3 months postoperatively for the final restoration.

Figure 7

(a) Provisional prosthesis (Group S); (b) Screw-retained provisional prosthesis (Group S)

Figure 8

Screw-retained provisional prosthesis (Group C)

Final prosthetic procedure

After 3.5 months, the screw-retained temporaries were removed and the gingival profile was evaluated for any inflammation [Figures 9 and 10]. In case of the implant placements with the socket shield, it was checked whether there was an exposure of shield or not. A putty index was made using provisional crown, and then using flowable pattern resin, impression copings were customized to make an exact replica of the emergence profile. Open-tray implant-level impressions were made using heavy body and light body additional silicone impression material in custom tray. The jig trial was done and customized zirconia abutments with lithium disilicate (Emax) crowns were placed 4 months postimplant placement [Figures 11a, b and 12]. The recall was done after 15 days after the placement of the definitive crown, and clinical and radiographic evaluations were done for bone and soft-tissue profile [Figures 13 and 14]. Oral hygiene instructions were given.

Figure 9

Emergence profile after 3.5 months (Group S)

Figure 10

Emergence profile after 3.5 months (Group C)

Figure 11

(a) Customized zirconia abutment (Group S); (b) Final prosthesis cemented (Group S)

Figure 12

Final prosthesis cemented (Group C)

Figure 13

Postoperative X-ray (Group S)

Figure 14

Postoperative X-ray (Group C)

Collection of data

Both the groups were analyzed at two different time intervals: 15 days after the placement of provisional restoration and 15 days after the placement of a definitive prosthesis. The clinical measurements and radiographic assessments were done and recorded by a different operator who did not participate in any other part of the study and was blinded for the procedure done on the patients.

Five soft-tissue parameters which were recorded for esthetic analysis using Pink Esthetic Index (PES) were mesial papilla, distal papilla, curvature of the facial mucosa, level of the facial mucosa, and root convexity (RC) at the buccal aspect of the implant site [Table 1]. These scores were analyzed on the standardized digital photographs obtained using the Digital SLR Camera (DSLR) (Canon 600D) and 100-mm macro lens (canon) at the fixed magnification of 1.5:1. All five PES parameters were assigned a score of 0, 1, or 2, so the maximum possible PES was 10.

The radiological scores were obtained from digital periapical radiographs. To avoid errors, the long-cone paralleling technique was used for radiographs. Measurements were noted between the proximal crestal bone level and the implant platform both mesially (AM) and distally (AD) in all the samples [Figure 15]. Since implant length is fixed, it was used as a reference length to calibrate for elongation or foreshortening of the radiographic image.

Figure 15

Radiological assessment of interproximal bone

Statistical analysis

Data obtained were tabulated on an MS Office Excel Sheet (version 2010, Microsoft Redmond Campus, Redmond, Washington, USA). Statistical analysis of the data was done using the Statistical Package for Social Sciences (SPSS) (SPSS version 21.0, IBM). Descriptive statistics such as frequencies and percentages for categorical data along with mean and standard deviation for numerical data were also depicted.

Using the Shapiro–Wilk test, it was found that the data followed a normal bell-shaped curve; therefore, parametric tests were used for comparisons. Data collected were subjected to intragroup comparison (two groups) using paired t-test and intergroup comparison using t-test. Chi-square test was done to compare the frequencies of different variables with group. For all the statistical tests, P < 0.05 was considered to be statistically significant.

RESULTS

In this study, thirty immediate extraction sites were treated with implant-retained prosthesis using two different surgical techniques. The test group (Group S) comprised 15 sites with SSTs and the control group (Group C) comprised 15 sites which were treated with conventional technique without a shield. At the 3-month period, when the patient was called for final impression procedures, in one of the cases of SST, the shield was exposed. The shield was trimmed gently, and the impression was made. All the implant sites showed uneventful healing. All patients received customized zirconia abutments with lithium disilicate (Emax) crowns.

Measurement of different soft-tissue parameters included in Pink Esthetic Score (PES) was done 15 days after the provisional prosthesis (PES1) and 15 days after permanent prosthesis (PES2) [Table 2].

Table 2

Table depicting the intragroup and intergroup comparison between PES in the control (Group C) and test (Group S) groups at two different time intervals (PES1 and PES2)

Site	Control (Group C)		Test (Group S)
	PES1	PES2	PES1	PES2
1	10	9	10	10
2	10	8	10	10
3	8	7	10	10
4	9	8	10	10
5	9	8	10	10
6	9	7	8	8
7	10	7	10	10
8	10	7	10	10
9	7	5	10	10
10	10	8	10	9
11	9	7	10	9
12	10	7	9	8
13	9	6	10	8
14	6	5	10	8
15	9	4	9	7
Total	135	103	146	137
Average	9	6.867	9.733	9.133

PES1: Pink Esthetic Score done 15 days after provisional prosthesis; PES2: Pink Esthetic Score done 15 days after permanent prosthesis

It was observed that in test group S, a range of PES2 scores was 7–10 with none of the individuals scoring <7. On the other hand, the range of PES2 scores for control group C was 4–9 with a peak of 7 [Table 2].

A high statistically significant difference was seen between the two techniques for the values (p < 0.01) for the PES score at second-time interval PES2 [Table 3 and Figure 16]. A statistically highly significant difference was also observed for the values for the difference of the mean values of PES (PES1-PES2) at the two different intervals [Table 4 and Figure 17]. From the statistical data, it was observed that across the two different time intervals, PES scores have worsened significantly in the control group (Group C) as compared to the test group (Group S). The null hypothesis was therefore rejected, and the alternative hypothesis was accepted.

Table 3

Table depicting the intergroup comparison between mean values, standard deviation, T value and P value of variable “PES2”

Group	n	Mean	SD	SEM	T	P
Control	15	6.87	1.357	0.350	4.9999	0.000*
Test	15	9.13	1.0333	0.262

*Statistically highly significant difference (P<0.01), SD - Standard deviation; SEM - Standard error of mean; n - Sample size; T - T value; P - P value of t test; PES - Pink Esthetic Score

Figure 16

Comparison of total values of variable “PES” among the two groups at two different time intervals (PES1 and PES2)

Table 4

Table depicting the intergroup comparison between mean values, standard deviation, T value and p value of change in variable “PES” (PES1-PES2) at two different time intervals

Group	n	Mean	SD	T	P
Control	15	2.1333	1.12546	−0.4250	0.000*
Test	15	0.6000	0.82808

*Statistically highly significant difference (P<0.01). SD - Standard deviation; n - Sample size; T - T value; P - P value of t test; PES - Pink Esthetic Score

Figure 17

The intergroup comparison between mean values of change in relation to variable “PES” (PES1-PES2) at two different time intervals

Radiographically, mesial (AM) and distal (AD) interdental bone levels were measured from the height of interproximal bone (both mesially and distally) to the implant platform 15 days after the provisional prosthesis (AM1, AD1) and 15 days after permanent prosthesis (AM2, AD2). No statistically significant difference was observed between the two techniques for the mean of radiological scores. Descriptive radiological scores of differences in the mean scores of bone height mesially (AM1–AM2) and distally (AD1–AD2) were significantly better for test group S as compared to control group C. Therefore, it was analyzed that within the limited time frame, group S shows less loss of interproximal bone than group C [Figures 18 and 19].

Figure 18

The intergroup comparison between change of mean values (AM1-AM2) in relation to variable “AM” at two different time intervals (interproximal bone mesially to implant platform)

Figure 19

The intergroup comparison between change of mean values (AD1-AD2) in relation to variable “AD” at two different time intervals (interproximal bone distally to implant platform)

DISCUSSION

An acceptable technique for rehabilitating a nonrestorable tooth is the one which is simple, minimally invasive, and is able to preserve the attached gingiva and soft-tissue contours. Retaining and maintaining the gingival contour is one of the most crucial factors in the esthetic rehabilitation of the maxillary anterior region. As implants can never exceed the natural tooth's ability to preserve the surrounding bone, immediate implant placements have been observed to be associated with socket and ridge remodeling. On the other hand, preserving the attachment apparatus of natural teeth can actually preserve and maintain the shape of alveolar bone along with the gingival and alveolar mucosa.

This clinical study presents a direct comparison of esthetics and soft-tissue evaluation between implants placed immediately after the extraction of the root stump using SST (15 sites) and without SST (15 sites). PES is a predictable measure of esthetics achieved with implant restorations.[151617] Measurement of different soft-tissue parameters and PES were found to show a positive correlation with the descriptive radiological scores.

According to the studies previously published, the preserved root shield preserves the bone-periodontal attachment apparatus that includes root cementum, PDL, periodontal fibers, blood supply, bundle bone, and alveolar bone. The vital and undamaged buccal root fragment prevents the expected postextraction socket remodeling and also supports the buccal/facial tissues.[2122] Contrary to this, when the complete root is extracted, buccal bone loses the blood supply that comes from the socket side and this results in the resorption of some buccal bone.

In the current study, when the intragroup comparison of RC scores was made, it was concluded that RC score was maintained in all the cases of Group S while a decrease was seen in all the cases of Group C. This means root convexity (hence the buccal bone) was maintained in all the cases of Group S.

Although the study affirms that SSTs can be chosen as a viable alternative to conventional implant placement techniques, more studies involving bigger sample sizes and having much longer follow-up periods are required.

CONCLUSION

It is concluded that better soft-tissue parameters can be achieved with the SST as compared to a conventional graftless technique whenever a restoration on immediate implant placement is considered. The SST serves as a reassuring technique in terms of preserving and maintaining pink esthetics and providing a definitive and predictable treatment modality for cases with high esthetic risk such as high lip line and maxillary anterior region. At the same time, the limited follow-up time period should be considered when looking at the outcomes of this study. Further multicentric studies with larger sample sizes and longer duration need to be carried out in order to validate the findings of the current study so that SST can be relied upon as a routine procedure for the immediate extraction cases in the esthetic zone.

Financial support and sponsorship

This study was financially supported by the Indian Council of Medical Research, Department of Health, Government of India, and Megagen Implants Co. Ltd., Korea.

Conflicts of interest

There are no conflicts of interest.