Interim tissue changes following connective tissue grafting and two-stage implant placement. A randomized clinical trial

Protein profile at newly restored implants compared to contralateral teeth over 12-months: a pilot study

OBJECTIVES

To determine crevicular fluid alterations in protein expression of newly restored implants during their first year of function and associate them with those of contralateral teeth.

MATERIALS AND METHODS

In ten non-smokers, successfully treated for periodontitis, one newly restored implant (baseline-T0) and one corresponding tooth were followed for 12-months (T1). Oral hygiene was monitored during the study. Periodontal clinical indices and crevicular fluid were collected from an implant-site (PICF) and a tooth-site (GCF). Total proteomic profiles of PICF and GCF were investigated using label-free quantitative proteomics.

RESULTS

Clinical recordings remained stable at 12-months on the tooth-/implant-site basis. The comparative analysis of protein enrichment between teeth and implants at T0 revealed 664 human proteins, with 93 found only in teeth and 217 exclusively in implants. Among the 354 overlapping proteins, 46 were upregulated (log2FC > 1) in teeth, while 61 in implants. At T1, 569 human proteins were exclusively identified, with 67 found only in teeth and 193 exclusively in implants. Of the 309 overlapping proteins, 22 were upregulated in teeth, while 48 were in implants. The over-representation enrichment analysis identified "interferon-alpha response" and "allograft rejection" pathways, as significantly regulated categories at T0, with the latter being over-represented at T1.

CONCLUSIONS

Peri-implant tissue maturation was evident during the study. Proteins expressed in crevicular fluid reflected unique patterns between implants and teeth that are worth studying.

CLINICAL RELEVANCE

Different proteomic patterns were observed at the implant-site compared to the contralateral tooth-site towards inflammatory processes that prevail within otherwise clinically healthy peri-implant tissues.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov ID: NCT06379022.

Association of Connective Tissue Grafts in Immediate Implants: Systematic Review and Meta-Analysis

BACKGROUND

The increase in soft tissue (ST) around implants can benefit peri-implant health and aesthetic results. The objective was to compare the gingival and esthetic health benefits of immediate implant placement (IIP) with simultaneous or delayed connective tissue graft (CTG) compared to IIP without CTG.

METHODS

A systematic review was carried out by two reviewers in Medline-Pubmed, Scopus, and Cochrane. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were considered. Randomized Clinical Trials (RCTs) that were published between April 2017 and February 2024 were used. Studies that analyzed the performance of a simultaneous or deferred CTG after the placement of an implant in the aesthetic zone, with or without immediate provisionalization, without previous regeneration, with a follow-up of 6 months, and that were performed in humans were included.

RESULTS

Quantitative analysis was performed using data provided by the RCTs. The five RCTs that were selected analyzed a total "n" of 245 subjects who met the inclusion criteria and focused on the subject of the study. In the quantitative analysis, four RCTs were included. The studies evaluated buccal gingiva levels when placing the IIP with and without CTG, obtaining a mean buccal gingiva level difference of 0.09 mm (95% CI: -0.54 to 0.72, p = 0.05), statistically not significant, but with a favorable trend.

CONCLUSIONS

The use of CTG associated with the II can maintain the gum level but not increase the volume. CTG is favorable for achieving successful esthetic results when immediate placement of an implant with a provisional prosthesis is planned.

Effect of peri-implant mucosal thickness on esthetic outcomes and the efficacy of soft tissue augmentation procedures: Consensus report of group 2 of the SEPA/DGI/OF workshop

OBJECTIVES

The aim of this study was to comprehensively assess the literature in terms of the effect of peri-implant mucosal thickness on esthetic outcomes and the efficacy of soft tissue augmentation procedures to increase the mucosal thickness with autogenous grafts or soft tissue substitutes.

MATERIAL AND METHODS

Two systematic reviews (SR) were performed prior to the consensus meeting to assess the following questions. Review 1, focused question: In systemically healthy patients with an implant-supported fixed prosthesis, what is the influence of thin as compared to thick peri-implant mucosa on esthetic outcomes? Review 2, focused question 1: In systemically healthy humans with at least one dental implant (immediate or staged implant), what is the efficacy of connective tissue graft (CTG), as compared to absence of a soft tissue grafting procedure, in terms of gain in peri-implant soft tissue thickness (STT) reported by randomized controlled clinical trials (RCTs) or controlled clinical trials (CCTs)? Review 2, focused question 2: In systemically healthy humans with at least one dental implant (immediate or staged implant), what is the efficacy of CTG, as compared to soft tissue substitutes, in terms of gain in peri-implant STT reported by RCTs or CCTs? The outcomes of the two SRs, the consensus statements, the clinical implications, and the research recommendations were discussed and subsequently approved at the consensus meeting during the group and plenary sessions.

CONCLUSIONS

There was a tendency of superior esthetic outcomes in the presence of a thick mucosa. The connective tissue graft remains the standard of care in terms of increasing mucosa thickness.

Efficacy of soft tissue augmentation procedures on tissue thickening around dental implants: A systematic review and meta-analysis

OBJECTIVES

The first focused question (FQ1) was: What is the efficacy of connective tissue graft (CTG), as compared to the absence of soft tissue grafting procedure, in terms of gain in peri-implant soft tissue thickness (STT) reported by randomized controlled clinical trials (RCTs) or controlled clinical trials (CCTs)? The second focused question (FQ2) was: What is the efficacy of CTG, as compared to soft tissue substitutes, in terms of gain in peri-implant STT reported by RCTs or CCTs?

MATERIALS AND METHODS

A manual and electronic search was performed for each question to identify RCTs and CCTs published up to July 2020. The primary outcome variable was changes in peri-implant STT and secondary outcomes were marginal bone level (MBL), clinical parameters for the diagnosis of peri-implant health, changes in the position of peri-implant soft tissues, esthetic outcomes, and patient-related outcome measures (PROMs). For primary and secondary outcomes, data reporting mean values and standard deviations for each study were extracted. Weighted mean differences (WMDs) or standardized mean differences as well as 95% confidence intervals (CIs) and prediction intervals (PIs) were calculated.

RESULTS

Eight trials were included to answer the first focused question and eight to answer the second one, providing data for 254 and 192 patients, respectively. For the first focused question, a statistically significant difference of 0.64 mm in STT was found in favor of the grafted group (n = 8; 95% CI [0.16; 1.13]; 95% PI [-1.06; 2.35]; p = .01). Moreover, sites treated with CTG exhibited statistically significant less recession than implants without a graft (n = 4; WMD = 0.50 mm; 95% CI [0.19; 0.80]; 95% PI [-0.70; 1.69]; p < .001). For the second focused question, the meta-analysis showed a statistically significant gain of STT in the CTG group when compared to soft tissue substitutes (n = 8; WMD = 0.51 mm; 95% CI [0.28; 0.75]; 95% PI [-0.09; 1.12]; p < .001). Furthermore, the use of CTG resulted in significantly higher pink esthetic score values (n = 3; WMD = 1.02; 95% CI [0.29; 1.74]; 95% PI [-3.67; 5.70]; p = .01) and less recession (n = 2; WMD = 0.50 mm; 95% CI [0.10; 0.89]; 95% PI [not estimable]; p = .014) when compared to soft tissue substitutes. No statistically significant differences between groups were observed for any of the following secondary variables: MBL, clinical parameters for the diagnosis of peri-implant health, position of the interproximal tissues, keratinized mucosa or PROMS (p > 0.05), except for medication intake, which was significantly higher when using CTG as compared to soft tissue substitutes (n = 2; WMD = 1.68; 95% CI [1.30; 2.07]; 95% PI [not estimable]; p < .001).

CONCLUSIONS

Soft tissue augmentation procedures are efficacious on soft tissue thickening and, in particular, CTG demonstrated a significant STT gain when compared to no graft or soft tissue substitutes.

Effect of customized healing abutments on the peri-implant linear and volumetric tissue changes at maxillary immediate implant sites: A 1-year prospective randomized clinical trial

BACKGROUND

Immediate implant placement (IIP) associated with the use of bone substitutes and collagen matrices (CM) seems to reduce the amount of resorption at peri-implant areas. Recently, customized healing abutments (CA) appeared as another solution in order to seal the socket and preserve the original soft tissue contour.

PURPOSE

To evaluate peri-implant tissues dimensional changes after using customized healing abutments compared with the use of xenogeneic collagen matrices as socket sealing options in flapless maxillary immediate implant placement.

MATERIAL AND METHODS

The present study was designed as a prospective, randomized, controlled clinical trial. Patients were allocated into two groups depending on the socket sealing option: in the CM group a collagen matrix was used and in the CA group a customized abutment. Digital impressions were taken prior to extraction, 1, 4, and 12 months after implant insertion and the digital files allowed to evaluate linear buccal changes (MBC) and the buccal volumetric variation (BVv) between the different time points at peri-implant tissue areas. Additionally, mucosa variation was computed assessing the papilla presence and the midfacial mucosa height. Statistical significance was set at 0.05.

RESULTS

Twenty-eight patients were observed during a 12-month period. Significant differences between mean values of BVv at the first month were observed at the CM and CA group (-9.75 ± 6.65% and -4.76 ± 5.29%, respectively) (p = 0.043). At the 1-year follow-up, no significant differences were found in terms of BVv between the two groups, although the thin bone phenotype (≤1 mm) significantly influenced the volumetric variations that occurred in each group. No significant differences were noticed in midfacial mucosa and papillae alteration between groups, after 1 year of treatment.

CONCLUSION

Both treatment options are predictable solutions for socket sealing in IIP, although a higher volumetric variation can be expected in the presence of thin bone phenotypes.

Volumetric changes at implant sites: A systematic appraisal of traditional methods and optical scanning-based digital technologies

AIM

To evaluate techniques for assessing soft tissue alterations at implant sites and compare the traditionally utilized methods to the newer three-dimensional technologies emerging in the literature.

MATERIALS AND METHODS

A comprehensive search was performed to identify interventional studies reporting on volumetric changes at implant sites following different treatments.

RESULTS

Seventy-five articles were included the following: 30 used transgingival piercing alone, one utilized calliper, six with ultrasonography, six on cone-beam computed tomography, and 32 utilized optical scanning and digital technologies. Optical scanning-based digital technologies were the only approach that provided 'volumetric changes,' reported as volumetric variation in mm³ , or the mean distance between the surfaces/mean thickness of the reconstructed volume. High variability in the digital analysis and definition of the region of interest was observed. All the other methods reported volume variation as linear dimensional changes at different apico-coronal levels. No studies compared volumetric changes with different approaches.

CONCLUSIONS

Despite the emergence of optical scanning-based digital technologies for evaluating volumetric changes, a high degree of variation exists in the executed workflow, which renders the comparison of study results not feasible. Establishment of universal guidelines could allow for volumetric comparisons among different studies and treatments.

The integrated stress response induces R-loops and hinders replication fork progression

The integrated stress response (ISR) allows cells to rapidly shutdown most of their protein synthesis in response to protein misfolding, amino acid deficiency, or virus infection. These stresses trigger the phosphorylation of the translation initiation factor eIF2alpha, which prevents the initiation of translation. Here we show that triggering the ISR drastically reduces the progression of DNA replication forks within 1 h, thus flanking the shutdown of protein synthesis with immediate inhibition of DNA synthesis. DNA replication is restored by compounds that inhibit eIF2alpha kinases or re-activate eIF2alpha. Mechanistically, the translational shutdown blocks histone synthesis, promoting the formation of DNA:RNA hybrids (R-loops), which interfere with DNA replication. R-loops accumulate upon histone depletion. Conversely, histone overexpression or R-loop removal by RNaseH1 each restores DNA replication in the context of ISR and histone depletion. In conclusion, the ISR rapidly stalls DNA synthesis through histone deficiency and R-loop formation. We propose that this shutdown mechanism prevents potentially detrimental DNA replication in the face of cellular stresses.