Comparison of the effect of zirconia and titanium abutments on peri-implant hard and soft tissues

Abstract

Aim:

The primary objective of this research was to assess and compare the impact of customized zirconia (Zr) and titanium (Ti) abutments, placed on early loaded dental implants, on both hard tissue (as measured crestal bone level) and soft tissue (as assessed by sulcular bleeding index [SBI], probing depth [PD], and Pink Esthetic Score [PES]), through clinical and radiographic evaluation.

Settings and Design:

This research involved a sample of 15 patients who had partially dentulous mandibular arch. Within this group, a total of 30 implants were surgically placed. Specifically, each patient received two implants in the posterior region of the mandible, and the bone density in this area was classified as D2 type. In each patient, one implant was loaded with Zr abutment and the other was loaded with Ti abutment. The bone quality in the area of implant placement was Type D2. Two groups were created for this research. Each group consisted of 15 early loaded dental implants with customized Zr abutments and customized Ti abutments respectively.

Materials and Methods:

Hard- and soft-tissue changes were evaluated in both the groups. Evaluation of crestal bone loss (CBL) with cone beam computed tomography and SBI, PD and PESs were evaluated by various indices at 2, 4, and 6 months postloading.

Statistical Analysis Used:

After obtaining the readings, data were subjected to statistical analysis and comparison of quantitative data was done, paired t-test was used.

Results:

The mean CBL in the Ti abutment is higher; the difference between the two groups was not statistically significant. SBI and PD for Zr were higher, but there was no statistically significant difference between the two groups. Zr had a higher PES than Ti abutment and the difference between the two groups was statistically significant. In the literature till date, the PES of Zr abutments were proven better for provisional restorations in implant prosthesis, but very few literatures support the same for the final implant restorations.

Conclusion:

The study did not reveal a clear advantage of either Ti or Zr abutments over the other. Nevertheless, Zr abutments tended to produce a more favorable color response in the peri-implant mucosa and led to superior esthetic outcomes as measured by the PES.

INTRODUCTION

The field of dental implant has expanded significantly in the past few decades, bringing innovation with increasing the range of available treatments. One aspect of this advancement is specifically related to the prosthetic abutments. The prosthetic abutment attaches to the implant platform and serves as a connection point between the future superstructure or prosthesis and the fixture. In systematic reviews, titanium (Ti) has maintained a leading position as an abutment material. Due to their well-documented biocompatibility and mechanical characteristics, Grade 5 Ti alloys are typically used to create custom Ti abutments. However, the optical result may be harmed if the metallic color of Ti continues to shine through the mucosa. A dull gray shine through, even if placed sub gingivally, could make the soft tissue appear artificial.[1]

The development of tooth-colored ceramic and personalized implant abutments is a result of consumer demand for extremely esthetic restorations. From an esthetic standpoint, especially for patients with thin, mucosal tissues, and customized zirconia (Zr) implant abutments are advised. Zr is superior to Ti, having less plaque accumulation with similar soft-tissue response, probing depths (PDs), bleeding on probing, and marginal bone level.[2] Although, Ti abutments are still considered better mechanically and more reliable as compared to Zr when exposed to long term clinical function.[1]

Literature provides very limited evidence on comparative clinical evaluation of customized Zr and Ti abutments. Hence, this in vivo research aimed to compare and evaluate the hard- and soft-tissue response around early loaded dental implants with customized Zr and Ti abutments.

MATERIALS AND METHODS

The Institutional Ethical Committee gave its Clearance under number IDST/IEC/2020-23/28. The Clinical Trial Registry of India received the study registration. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp. Released 2012 was used to estimate the sample size. Fifteen partly edentulous individuals (male and female) between the ages of 30 and 50 years had 30 dental implants implanted. Two groups were created for the investigation. Fifteen early loaded dental implants in Group 1 had a customized Zr abutment, while 15 early loaded implants in Group 2 had a customized Ti abutment. An appointment for diagnosis marked the beginning of the trial regimen. According to the inclusion, exclusion, and laboratory investigation criteria, all 15 patients were chosen.

Inclusion criteria

• Age 30–50 years

• Partially edentulous sites

• Extraction socket that has healed

• No occlusal disharmony

• Sufficient height and quantity of bone for implant placement

• COVID-19 (reverse transcription polymerase chain reaction report) negative

• Having good dental and general wellness.

Exclusion criteria

• Immunocompromised state

• Chronic bone diseases

• Psychiatric disorders

• Uncontrolled diabetes

• Pregnant or lactating females.

A thorough clinical examination, radiographic assessment involving the cone beam computed tomography (CBCT) was done [Figure 1]. All treatment options were thoroughly discussed with the patients. The relative advantages and disadvantages of implant treatment were informed. The surgical procedure was adequately explained and thereafter, a written consent was taken from all the patients.

Figure 1.

Preoperative cone beam computed tomography field of view

After making diagnostic impressions with alginate, Type 2 dental stone was used to pour the cast, bite registration was recorded and semi adjustable articulator was used to mount the cast. With the help of vacuum forming machine, thermoplastic material was applied to the cast, and stents were made to direct the surgical drills during surgery.

A presurgical prophylactic dose of 2 g Amoxicillin 1 h before the surgery was prescribed to the patient. The patient was instructed to do intraoral rinses with 0.12% chlorhexidine after the surgical site was prepped with 5% betadine paint.

Local anesthesia (2% Lignocaine with 1:100,000 adrenaline) was administered using disposable syringe and a mid-crestal incision was given in mandibular posterior region with no. 15 BP blade [Figure 2]. Two releasing incisions were placed on the mesial and distal aspect to raise a full thickness mucoperiosteal flap. Surgical guide was then placed in position, and the initial osteotomy was performed using pilot drill. The complete osteotomy was obtained after using all the required surgical drills in the progressively increasing diameter. The depth of the osteotomy site was measured with the help of implant depth gauge.

Figure 2.

Mid crestal incision and flap raised wrt 46, 47 region

Then, using an implant driver and a torque wrench, implants were placed [Figure 3] at the site of the osteotomy with an insertion torque of 30–50 Ncm, according to the available bone density, healing abutments were attached and primary closure of the surgical site was achieved [Figure 4]. The healing abutments were then taken out and the closed tray impression copings were attached for making closed tray implant level impressions with the help of polyvinyl siloxane (putty and light body consistency) (Photosil DPI, India) impression material. At the end, healing abutments were reattached followed by postoperative instructions and medications were prescribed to the patient.

Figure 3.

Implant placement done wrt 46, 47 region

Figure 4.

Healing abutment attached and suturing done

Final impression attached with lab analog was sent to the laboratory where the master casts were poured with Type IV Gypsum products and the scan bodies were attached to the cast followed by which the designing of the abutment was done according to the type of implants placed in the patient and milling of the abutments (Zr and Ti) were done with the help computer-aided-design/computer-aided-manufacturing software (3 Shape) [Figures 5 and 6]. The Porcelain Fused to Metal (DMLS) crowns were also fabricated in the laboratory.

Figure 5.

Designing of zirconia and titanium abutments wrt 46, 47

Figure 6.

Zirconia and titanium abutments

In the next appointment, the sutures were removed and customized Zr and Ti abutments were attached to the implants and were loaded functionally within a week [Figures 7 and 8].

Figure 7.

Zirconia and titanium abutment wrt 46, 47

Figure 8.

Implant loading with porcelain fused to metal (DMLS) crowns wrt 46, 47

At the 2^nd, 4^th, and 6^th months after loading, standardized follow-up exams were planned to evaluate both hard- and soft-tissue changes [Figure 9].

Figure 9.

Postoperative IOPA X- ray wrt 46, 47

Crestal bone loss was assessed with CBCT (Papaya 3D Plus, Genoray Korea Japan) postoperatively at 0, 2, 4, and 6 months to assess the hard-tissue changes for both the groups. At 2, 4, and 6 months postloading PD, bleeding index (BI), Pink Esthetic Score (PES), which includes the mesio-distal papilla, alveolar process deficiency, soft-tissue level, contour, color, and texture were all recorded to assess any change in both groups using the Hu-Friedy Colorvue plastic probe.

RESULTS

Data were collected and compiled methodically, converted from a pro forma with precoded fields to a computer, and a master table was created. The complete amount of data were thoughtfully distributed and displayed as separate tables and graphs.

Intergroup comparison of mean sulcular BI (SBI) at 2, 4, and 6 months was done using paired t-test. It was found that SBI for Group 1 is higher at recorded time intervals in comparison to Group 2. P value at 2 months was 0.650, at 4 months 0.825, and at 6 months 0.532, but the difference between the two groups was statistically not-significant [Table 1 and Graph 1].

Table 1.

Intergroup comparison of sulcular bleeding index

Groups	n	Mean	SD	P
At 2 months
Group 1	15	0.7833	0.18581	0.650, NS
Group 2	15	0.7500	0.21129
At 4 months
Group 1	15	0.5333	0.18581	0.825, NS
Group 2	15	0.5167	0.22093
At 6 months
Group 1	15	0.2333	0.11443	0.532, NS
Group 2	15	0.2000	0.16903

SBI: Sulcular bleeding index, NS: Not significant, SD: Standard deviation

Graph 1.

Intergroup comparison of sulcular bleeding index. SBI: Sulcular bleeding index

Intergroup comparison of mean PD at 2, 4, and 6 months was done using paired t-test. It was found that PD for Group 1 is higher at recorded time intervals in comparison to Group 2. P value at 2 months was 0.906, at 4 months 0.748, and at 6 months 0.683, but the difference between the two groups was not statistically significant [Table 2 and Graph 2].

Table 2.

Intergroup comparison of probing depth

Group	n	Mean	SD	P
At 2 months
Group 1	15	3.9500	0.33004	0.906, NS
Group 2	15	3.9333	0.42748
At 4 months
Group 1	15	3.4833	0.56273	0.748, NS
Group 2	15	3.4167	0.56432
At 6 months
Group 1	15	3.2500	0.60504	0.683, NS
Group 2	15	3.1667	0.49701

PD: Probing depth, NS: Not significant, SD: Standard deviation

Graph 2.

Intergroup comparison of probing depth

Intergroup comparison of mean PES at 2, 4, and 6 months was done using paired t-test. It was found that PES for Group 1 is higher at recorded time intervals in comparison to Group 2. P value at 2 months was 0.004, at 4 months 0.004, and at 6 months 0.008 and statistically significant difference was found in both the groups [Table 3 and Graph 3].

Table 3.

Intergroup comparison of Pink Esthetic Score

Group	n	Mean	SD	P
At 2 month
Group 1	15	7.8667	1.12546	0.004 (significant)
Group 2	15	6.5333	1.18723
At 4 months
Group 1	15	9.8000	1.20712	0.004 (significant)
Group 2	15	8.4667	1.12546
At 6 months
Group 1	15	11.4000	0.91026	0.008 (significant)
Group 2	15	10.3333	1.11270

PES: Pink Esthetic Score, SD: Standard deviation

Graph 3.

Intergroup comparison of Pink Esthetic Score. PES: Pink Esthetic Score

Intergroup comparison of mean crestal bone loss (CBL) at 2, 4, and 6 months was done using the paired t-test. It was found that mean CBL for Group 2 is higher at recorded time intervals in comparison to Group 1. P value at 2 months was 0.443, at 4 months 0.950, and at 6 months 0.170 and there was no significant difference in both the groups [Table 4 and Graph 4].

Table 4.

Intergroup comparison of crestal bone loss

Group	n	Mean	SD	P
At 2 month
Group 1	15	0.2340	0.16211	0.443, NS
Group 2	15	0.2823	0.17769
At 4 months
Group 1	15	0.4576	0.18525	0.950, NS
Group 2	15	0.4626	0.24331
At 6 months
Group 1	15	0.6829	0.20007	0.170, NS
Group 2	15	0.5706	0.23524

CBL: Crestal bone loss, SD: Standard deviation, NS: Not significant

Graph 4.

Intergroup comparison of crestal bone loss. CBL: Crestal bone loss

Obtained data showed bleeding on probing was higher for customized Zr abutment at recorded time intervals than customized Ti abutment, PD was less for customized Ti abutment compared to customized Zr abutment, PES was higher for customized Zr abutment at recorded time intervals and crestal bone loss was less for customized Zr abutment than customized Ti abutment.

DISCUSSION

The objective of this in vivo study was to examine and assess the hard- and soft-tissue response to early loaded dental implants with custom-made Zr and Ti abutments.

The CBCT was done to evaluate hard-tissue changes. The measuring tools used were provided within the Triana Software. Linear measurements were calculated using ruler tool to calculate distance on mesial and distal aspect to measure bone loss in coronal section and lingual and buccal aspect in sagittal section, respectively. Bone measurements calculated on 0, 2, 4, and 6 months postloading of implants were compared by using this tool to calculate bone loss at a given time. The soft-tissue changes were evaluated by using Hu-Friedy Colorvue plastic probe for the both groups.

According to the study's findings, Group 1 (customized Zr abutment) had higher mean SBI scores than Group 2 (customized Ti abutment) at the recorded time points of 2, 4, and 6 months; however, there was no significant difference in both the groups. Because of the young junctional epithelium around the dental implants, initial bleeding on probing was greater, although this gradually subsided over time.

The percentage reduction in the SBI decreased more quickly in Group 2 (Ti) than in Group I (Zr) from the 2^nd to 8^th months and from the 4^th to 6^th months, although the difference was not statistically significant.

Sailer et al. concluded that there was more bleeding on probing at the prosthesis supported by Zr abutment in comparison to Ti abutment.[3] However, Zembic et al.,[2] Lops et al.,[4] and Hosseini et al. (2013)[5] reported no significant difference in BOP around Zr and Ti abutments.

Payer et al. evaluated SBI around two-piece Zr implants with Ti abutments for 24 months and concluded that there was no statistical difference among both the groups.[6]

At the recorded time intervals of 2, 4, and 6 months, it was discovered that Group 2 (Ti) had lower mean scores for PD, but this difference between the two groups was once again not statistically significant. This may possibly be related to the initially immature junctional epithelium around the dental implants, which improve gradually overtime.

The percentage reduction in PD also showed a faster reduction from 2^nd to 4^th months and from 4^th to 6^th months in Group 2 (Ti) compared to Group 1 (Zr), but the difference was not statistically significant.

Sailer et al. and Carrillo de Albornoz et al. showed mean PD for Zr abutment (3.5 mm) was more than mean PD for Ti abutment (3.3 mm) at 1 year follow-up, but difference was not statistically significant between two groups.[3,7]

In contrast Lops et al. reported that mean PD for Zr abutment was less than mean PD for Ti abutment, but difference was not statistically significant between two groups.[4]

While considering the mean scores for PES, it was found that scores were considerably higher for Group 1 (Zr) at recorded time interval (2, 4, and 6 months) and there was a significant difference in both the groups.

The percentage increase in PES also showed a faster increase from 2^nd to 4^th months and from 4^th to 6^th months in Group 1 (Zr) compared to Group 2 (Ti) and the difference was statistically significant.

Payer et al. recorded PES to evaluate Zr and Ti abutments. The mean score for Zr abutments were higher after 24 months, showing a significant difference between the two.[6]

Zembic et al. - Papilla Index, Hosseini et al. (2013) - Copenhagen Index Score, and Carrillo de Albornoz et al. - Implant Crown Aesthetic Index reported that no significant difference was found between the two.[2,5,7]

Mean CBL was less for customized Zr abutment at recorded time intervals, but only for initial two follow-ups which were 2^nd and 4^th months. For the 3^rd follow-up which was at 6^th month, lesser CBL was found for customized Ti abutment than customized Zr abutment, but the difference between the two groups was nonsignificant.

Zembic et al., Lops et al., Hosseini et al. (2013), Payer et al., and Carrillo de Albornoz et al. reported on interproximal CBL. Studies that were included reported no significant differences in CBL among both the abutments.[2,4,5,6,7]

From observations, it can be deduced that the PD, bleeding on probing and CBL around implants were comparable with no statistical significant difference.

Significant difference was found in the PES among both the groups confirming the hypothesis that the Zr abutments can improve the esthetics around the dental implants compared to Ti abutment.

Furthermore, it was observed that the survival rate of early loaded implant was around 97% at 6 months. Occlusal loading 4–21 days after implant surgery is defined as “early loading.”

Pigozzo et al. stated that the overall survival rates were 97.5% for early loading at 1 year and 97.6% at 3 years.[8] Ganeles et al. stated that implant survival rate is around 97% for early loading protocol at 12 months.[9] Several studies supported early loading and stated that it is a good treatment alternative more esthetic and less time taking procedure.[10]

Limitation of this study was the short follow-up period and sample size was small. Further investigations including a large sample size and a long follow-up period to enhance the significance of the conclusion concerning the use and predictability of the Zr abutment.

CONCLUSION

Following conclusions were made based on the limitations of this study:

1. SBI was higher for customized Zr abutment at recorded time intervals than customized Ti abutment, but there was no significant difference between both the groups

2. PD was less for customized Ti abutment at recorded time intervals than customized Zr abutment, but there was no statistically significant difference between both the groups

3. PES was considerably higher for customized Zr abutment at recorded time interval than customized Ti abutment with statistically significant difference among both the groups. It showed potential to improve the esthetics with Zr abutments and the overall quality of the soft tissue was also improved around implants

4. Crestal bone loss was less for customized Zr abutment, but only for initial two follow-ups which were 2^nd and 4^th months. At the 6^th month, CBL was less for customized Ti abutment than customized Zr abutment, but the difference was statistically nonsignificant among both the groups.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.