Peri-implant soft tissue phenotype modification and its impact on peri-implant health: A systematic review and network meta-analysis

Design of customized soft-tissue substitutes for posterior single-tooth defects: A proof-of-concept in-vitro study

OBJECTIVES

Soft-tissue volume augmentation treatments do not provide the satisfactory long-term functional and esthetic outcomes. The aim of the study was to develop a standardized digital procedure to design individual soft-tissue substitutes (STS) and apply mathematical modeling to obtain average shape STS for single posterior tooth defects.

MATERIAL AND METHODS

Thirty-three casts from 30 patients were scanned. STS were designed with a computer-aided design software and a systematic procedure standardized the measurements across all STS using 3D-analysis software. The occlusal, mesial-distal, and buccal-lingual planes were defined to partition, each STS and produce a mesh. The thickness values of each 3D slice were documented in a coordinate system chart to generate a scatter graph. Graphs were embedded into images (Orange software) and images were analyzed via hierarchical clustering.

RESULTS

Three STS groups were identified according to shape. Two shapes corresponded to the maxilla defects: a square (n = 13) with dimensions of 10 mm in a lingual-buccal (length) and 7-10 mm in a mesial-distal (width) direction; a rectangle (n = 11) of 11 mm in length and 4-7 mm in width. The average shape for mandible defects (n = 9) was smaller (6-8 mm in length, 5-10 mm in width). The highest thickness in all STS was in the buccal portion, above the alveolar ridge, with median values of 2 mm. The lowest thickness of 0.2 mm was at the edges.

CONCLUSIONS

The study developed novel methodology to design customized, as well as average shape STS for volume augmentation. Future STS harboring adapted geometry might increase volume augmentation efficiency and accuracy, while reducing surgical time.

Regenerative Medicine Technologies to Treat Dental, Oral, and Craniofacial Defects

Additive manufacturing (AM) is the automated production of three-dimensional (3D) structures through successive layer-by-layer deposition of materials directed by computer-aided-design (CAD) software. While current clinical procedures that aim to reconstruct hard and soft tissue defects resulting from periodontal disease, congenital or acquired pathology, and maxillofacial trauma often utilize mass-produced biomaterials created for a variety of surgical indications, AM represents a paradigm shift in manufacturing at the individual patient level. Computer-aided systems employ algorithms to design customized, image-based scaffolds with high external shape complexity and spatial patterning of internal architecture guided by topology optimization. 3D bioprinting and surface modification techniques further enhance scaffold functionalization and osteogenic potential through the incorporation of viable cells, bioactive molecules, biomimetic materials and vectors for transgene expression within the layered architecture. These computational design features enable fabrication of tissue engineering constructs with highly tailored mechanical, structural, and biochemical properties for bone. This review examines key properties of scaffold design, bioresorbable bone scaffolds produced by AM processes, and clinical applications of these regenerative technologies. AM is transforming the field of personalized dental medicine and has great potential to improve regenerative outcomes in patient care.

Is there any biomaterial substitute for peri-implant soft tissue phenotype modification? A network meta-analysis of the appraisal literature

Evidence shows that an increased width and thickness of the keratinized mucosa favours peri-implant health. The aim of this network meta-analysis was to compare the clinical effects of alternative biomaterials for peri-implant soft tissue phenotype modification (PSPM) in patients with dental implants when compared to autologous tissue grafts. An electronic search without language or date limitations was performed in four databases and the grey literature for articles published until November 2020. The eligibility criteria included randomized clinical trials (RCTs) evaluating the clinical outcomes of biomaterials for PSPM. A pairwise and network meta-analysis was conducted for each parameter to assess and compare the outcomes between the different treatment arms for the primary and secondary outcomes. A total of 11 RCTs were included in this review. The free gingival graft (FGG) showed the best clinical effect for increasing keratinized mucosa width (KMW). When compared in a network, the FGG demonstrated the best treatment ranking of probability results, followed by connective tissue graft (CTG), acellular dermal matrix (ADM), and xenogeneic collagen matrix (XCM). For the parameters 'mucosa thickness' and 'participant satisfaction with aesthetics', the results were CTG > ADM > XCM and XCM > ADM > CTG, respectively. Autogenous tissue grafts (FGG/CTG) demonstrate the best results in increasing KMW and mucosa thickness when compared to the other biomaterials.

Patient-reported outcome measures and clinical outcomes following peri-implant vestibuloplasty with a free gingival graft versus xenogeneic collagen matrix: a comparative prospective clinical study

BACKGROUND

The objective of this study was to compare patient-reported outcome measures (PROMs) and clinical outcomes after augmentation with xenogeneic collagen matrix (XCM) or free gingival graft (FGG) during different postoperative phases.

METHODS

Forty-two patients (21 per group) with keratinized mucosa width (KMW) of < 2 mm at buccal implant sites in the posterior mandible were enrolled. All underwent vestibuloplasty and were allocated to either FGG (control) or XCM (test) group. Intraoperative morbidity of pain, stress, nausea, tolerance to time, and acceptance of surgery were evaluated immediately after surgery. The severity and duration of subjective pain, swelling, and bleeding were compared within a 2-week postoperative period. The willingness to retreat and satisfaction were assessed at 6 months. All PROMs were obtained using questionnaires and visual analog scales. The buccal KMW and other peri-implant parameters were also evaluated.

RESULTS

No significant between-group differences were observed in PROMs immediately after surgery, except acceptance of surgery (0, 0-30.0 vs. 30, 0-50.0, p = 0.025). At 2 weeks, pain severity (46.7 ± 25.9 vs 61.9 ± 20.2, p = 0.040) and duration (5.52 ± 3.57 vs 8.48 ± 2.80, p = 0.005) were significantly lower in the test group, and pain perception during speaking and chewing was significantly higher for FGG, with no significant between-group differences in swelling and bleeding. At 6 months, the test group showed a higher willingness to retreat (76% vs 43%, p = 0.021); however, satisfaction with treatment outcomes was similar in both groups. At 6 months, the gain of KMW was significantly higher in FGG than in XCM (XCM: 1.57 ± 1.69 mm, FGG: 2.68 ± 1.80 mm, p = 0.003). Other peri-implant parameters did not show significant differences.

CONCLUSIONS

Within the limitation of the present nonrandomized study, XCM demonstrated more positive PROMs than FGG during different postoperative phases, mainly for less pain perception during the early healing stage, but was inferior to FGG in terms of gain of KMW. For KMW augmentation in the posterior mandible, XCM may be indicated when patients can bear little pain.

CLINICAL TRIAL REGISTRATION

ChiCTR1900022575 , date of registration: 17/4/2019, retrospectively registered.

Clinical evaluation of xenogeneic collagen matrix versus free gingival grafts for keratinized mucosa augmentation around dental implants: A randomized controlled clinical trial

AIM

To evaluate the outcomes of an apically repositioned flap (ARF) plus xenogeneic collagen matrix (XCM) in augmenting keratinized mucosa width (KMW) around dental implants when compared with ARF plus free gingival grafts (FGG).

MATERIALS AND METHODS

Twenty-six participants with at least one site with KMW ≤2 mm were randomized into FGG or XCM group. Clinical examinations were performed at baseline and at 2 and 6 months after surgery, including KMW, keratinized mucosa thickness, gingival index (GI), and probing depth (PD). Post-operative pain and patient satisfaction were also evaluated.

RESULTS

At 6 months, FGG attained a greater increase of KMW and thicker mucosa than XCM (4.1 ± 1.6 mm vs. 1.8 ± 1.0 mm, p < .001; 1.7 ± 0.6 mm vs. 1.2 ± 0.3 mm, p < .01). Regarding GI, PD, post-operative pain, aesthetic outcomes, and patient satisfaction, no significant difference could be detected. Moreover, the operation time of XCM group was shorter (60 ± 9 min vs. 39 ± 8 min, p < .001).

CONCLUSIONS

FGG could result in greater increase of KMW than XCM, though both could increase KMW, maintain peri-implant health, and attain comparable aesthetic outcomes. The use of XCM was associated with reduced operation time.

Osteoconductive Properties of a Volume-Stable Collagen Matrix in Rat Calvaria Defects: A Pilot Study

Volume-stable collagen matrices (VSCM) are conductive for the connective tissue upon soft tissue augmentation. Considering that collagen has osteoconductive properties, we have investigated the possibility that the VSCM also consolidates with the newly formed bone. To this end, we covered nine rat calvaria circular defects with a VSCM. After four weeks, histology, histomorphometry, quantitative backscattered electron imaging, and microcomputed tomography were performed. We report that the overall pattern of mineralization inside the VSCM was heterogeneous. Histology revealed, apart from the characteristic woven bone formation, areas of round-shaped hypertrophic chondrocyte-like cells surrounded by a mineralized extracellular matrix. Quantitative backscattered electron imaging confirmed the heterogenous mineralization occurring within the VSCM. Histomorphometry found new bone to be 0.7 mm² (0.01 min; 2.4 max), similar to the chondrogenic mineralized extracellular matrix with 0.7 mm² (0.0 min; 4.2 max). Microcomputed tomography showed the overall mineralized tissue in the defect to be 1.6 mm³ (min 0.0; max 13.3). These findings suggest that in a rat cranial defect, VSCM has a limited and heterogeneous capacity to support intramembranous bone formation but may allow the formation of bone via the endochondral route.

Histologic composition of marginal mucosal tissue augmented by a resorbable volume-stable collagen matrix in soft tissue thickening procedures in humans: a morphometric observational study

AIM

This study aims to examine the composition of lining and masticatory mucosa at the pre- and post-soft tissue augmentation procedures with a volume-stable cross-linking collagen matrix (VCMX) in humans.

MATERIALS AND METHODS

In 12 patients, single implant sites were augmented with a VCMX. Biopsies were obtained including masticatory (MM) and lining (LM) mucosa before augmentation and at 12 weeks post-augmentation procedures. Rete pegs density (RPD), length (RPL), and blood vessel density (BVD) were histomorphometrically analyzed at both time points. Picrosirius red staining under polarized light microscopy was used to evaluate collagen fiber organization. The effects of time and tissue type were evaluated by ANOVA with repeated measures.

RESULTS

Both MM and LM areas demonstrated an increase in mean RPL following augmentation, 382.6 µm ± 95.1 vs. 290.5 µm ± 79.3 and 335.6 µm ± 94.2 vs. 292.9 µm ± 77.0, respectively (p < .05). There was a significant difference in the numbers of RP per 1 mm length (RPD) between the MM (9.2 ± 1.7) and LM (6.1 ± 2.8) mucosa but not between the pre- and post-VCMX augmentation time points. The mean BVD in the LM was greater than in the MM (5.5 ± 2.4 and 6.3 ± 2.4 vs. 3.4 ± 3.3 and 3.7 ± 1.8, respectively, p < .05) but not between time points. The collagen fiber arrangements pre- and post-augmentation were not significantly different.

CONCLUSION

Augmentation with VCMX did not alter the composition of lining and masticatory mucosa at implant sites.

CLINICAL RELEVANCE

A thick soft tissue phenotype around the implant neck is an important factor to maintain peri-implant health. A non-autogenous cross-linking collagen matrix is proposed as an alternate graft substitute in soft tissue augmentation procedures in order to improve implant soft tissue phenotype.

Role of thin gingival phenotype and inadequate keratinized mucosa width (<2 mm) as risk indicators for peri-implantitis and peri-implant mucositis

BACKGROUND

There is growing evidence on the impact of thin gingival phenotype (TnP) and inadequate keratinized mucosa width (KMW <2 mm) around dental implants on peri-implant health. This study investigated the role of TnP and inadequate KMW (<2 mm) as risk indicators for peri-implantitis and mucositis and on dental patient-reported outcomes.

METHODS

Sixty-three patients with 193 implants (mean follow-up of 6.9 ± 3.7 years) were given a clinical and radiographic examination and a questionnaire to assess patient awareness of food impaction and pain/discomfort. Chi-squared tests and regression analysis for clustered data were used to compare outcomes.

RESULTS

Implants with TnP had a statistically higher prevalence of peri-implantitis (27.1% versus 11.3%; PR, 3.32; 95% confidence interval (CI), 1.64-6.72; P = 0.001) peri-implant mucositis (42.7% versus 33%; PR, 1.8; 95% CI, 1.12-2.9; P = 0.016) and pain/discomfort during oral hygiene (25% versus 5%; PR, 3.7; 95% CI, 1.06-12.96; P = 0.044) than thick phenotype. Implants with inadequate KMW had a statistically higher prevalence of peri-implantitis (24.1% versus 17%; PR, 1.87; 95% CI, 1.07-3.25; P = 0.027) and peri-implant mucositis (46.6% versus 34.1%; PR, 1.53; 95% CI, 1-2.33; P = 0.05) and pain/discomfort during oral hygiene (28% versus 10%; PR, 2.37; 95% CI, 1.1-5.1; P = 0.027) than the adequate KMW. TnP was strongly associated with inadequate KMW (PR = 3.18; 95% CI, 1.69-6.04; P <0.001).

CONCLUSION

TnP and inadequate KMW (<2 mm) may be significant risk indicators for peri-implant disease and pain/discomfort during brushing.

Ibero-Panamerican Federation of Periodontics Delphi study on the trends in diagnosis and treatment of peri-implant diseases and conditions: A Latin American consensus

BACKGROUND

The social diversity, heterogeneous culture, and inherent economic inequality factors in Latin America (LA) justify conducting a comprehensive analysis on the current status and future trends of peri-implant diseases and conditions. Thus, the aim of this Delphi study was to predict the future trends in the diagnosis and treatment of peri-implant diseases and conditions in LA countries for the year 2030.

METHODS

A Latin American steering committee and group of experts in implant dentistry validated a questionnaire including 64 questions divided into eight sections. The questionnaire was run twice with an interval of 45 days, with the results from the first round made available to all the participants in the second round. The results were expressed in percentages and data was analyzed describing the consensus level reached in each question.

RESULTS

A total of 221 experts were invited to participate in the study and a total 214 (96.8%) completed the two rounds. Moderate (65%-85%) to high consensus (≥ 85%) was reached in 51 questions (79.69%), except in the questions dealing with "prevalence", where no consensus was reached. High and moderate consensus was attained for all the questions in three fields (risk factors and indicators, diagnosis and treatment of peri-implant conditions and deficiencies, and prevention and maintenance).

CONCLUSIONS

The present study has provided relevant and useful information on the predictions in the diagnosis and treatment of peri-implant diseases with a high level of consensus among experts. Nevertheless, there is still a lack of agreement in certain domains.

Is the use of platelet-rich fibrin effective in the healing, control of pain, and postoperative bleeding in the palatal area after free gingival graft harvesting? A systematic review of randomized clinical studies

OBJECTIVE

A systematic review (SR) was conducted to answer the following focused question based on PICO strategy: In patients who were submitted to harvesting palatal free gingival graft, could platelet-rich fibrin (PRF) application in comparison with another method improve the healing, pain, and control of postoperative bleeding in the palatal area in randomized clinical trials?

METHODS

A SR was conducted according to the PRISMA guidelines. The MEDLINE (PubMed), Scopus, Embase, and Web of Science databases were searched, and hand searches were made, covering the period up to August 2020, for randomized clinical trials (RCTs) reporting the effect of PRF membrane in postoperative palatal healing management compared with any other methods. The risk of bias (RoB) of the studies included was assessed by using the RoB 2 tool.

RESULTS

The electronic search strategy identified 150 articles. After title screening and abstract reading, 141 studies were excluded, and 9 full-text publications were comprehensively evaluated. Finally, 8 articles were included in the systematic review. Six studies showed that the PRF membrane was effective in improving wound healing during the first 2 weeks. As regards patient-centered outcomes, five studies showed that PRF promoted less postoperative pain. Finally, five studies that evaluated bleeding showed that the PRF membrane improved control of postoperative bleeding. RoB was classified as low in 4 studies, 3 with some concerns, and only one study did not describe the outcome data, and as this was missing, it was not possible to verify the protocol of data analysis for this study; therefore, it was classified as having high RoB.

CONCLUSION

Within the limitations of this study, the collective evidence emerging from this SR may support the use of PRF membrane in the palatal area after free gingival graft harvesting. The results of this review must be interpreted with caution, due to the low number of RCTs included and high degree of heterogeneity among the PRF protocols. Further well-designed RCTs with accurate protocol and standard PRF parameters are required in order to gain clear understanding of the influence of PRF on wound healing and patient-centered outcomes.

CLINICAL RELEVANCE

The use of PRF membrane for the protection of the palatal donor site following free gingival graft harvesting procedures improves wound healing and patients' quality of life.

Clinical evaluations of free gingival grafting before implant placement to increase keratinized tissue width in molar regions: A retrospective case series

OBJECTIVES

To evaluate the dimensional changes of the keratinized tissue width (KTW) in molar regions after augmentation by free gingival grafts (FGG) before implant placement.

MATERIAL AND METHODS

In seventeen patients, twenty implant sites in molar regions with KTW ≤3 mm at the buccal aspect received FGG 2 months before implant placement. KTW at the buccal aspect was measured before FGG (T0), immediately before implant placement (T1), at the time of impression taking for final prosthesis fabrication (T2), and at the end of the follow-up period after loading (T3, 12-48 months). Changes in KTW before and after FGG, as well as the alterations during the follow-up period after loading, were analyzed. Shapiro-Wilk test, paired Student's t test, and Wilcoxon signed-rank test were used for the data analysis at α = 0.05.

RESULTS

KTW at the buccal aspect of the alveolar ridge was observed with a significant gain of 5.9 ± 1.3 mm at T1 (p < .001). The shrinkage of KTW from T2 to T3 was 8.5%, which was limited but statistically significant (p = .008). KTW at the buccal aspect of implant restorations was 5.0 ± 1.5 mm at T3.

CONCLUSIONS

Within the limitations of the present study, our data suggest that using FGG to increase KTW in molar regions before implant placement had a predictable result. The buccal KTW had a limited reduction and was ≥3 mm with more than 12 months of follow-up after loading.

Ultrasonographic tissue perfusion analysis at implant and palatal donor sites following soft tissue augmentation: A clinical pilot study

AIM

To describe the application of power Doppler Ultrasonography (US) for evaluating blood flow at implant and palatal donor sites following soft tissue augmentation with the connective tissue graft (CTG).

MATERIALS AND METHODS

Five patients exhibiting a peri-implant soft tissue dehiscence received treatment with a coronally advanced flap and corresponding CTG. Power Doppler US was used for assessing blood volume at baseline, 1 week, 1 month, 6 months and 12 months post-surgery for assessing blood-flow dynamics at the implant and palatal donor sites. The speed-weighted and power-weighted colour pixel density (CPPD) were computed from colour velocity (CV) and colour power (CP), respectively.

RESULTS

A mean increase in CV of 199.25% was observed at the midfacial region of the implant sites after 1 week compared to baseline. CV and CP were increased in all sites at 1 week and 1 month. At 6 and 12 months, the mean CV appeared lower than baseline at the implant sites. CCPD was increased at the palatal donor sites and at the great palatine foramen areas at the 1-week and 1-month post-operative evaluations.

CONCLUSIONS

Power Doppler US is a non-invasive and valuable tool for estimating tissue perfusion and CPPD variation during different phases of intra-oral soft tissue graft healing.

Comparison of peri-implant clinical outcomes of digitally customized and prefabricated abutments: A systematic review and meta-analysis

BACKGROUND

Digitally customized abutments are increasingly used in contemporary implant prosthodontics.

PURPOSE

This systematic review and meta-analysis aimed at comparing the peri-implant clinical outcomes of digitally customized and prefabricated abutments.

MATERIALS AND METHODS

The search strategies included electronic databases (PubMed, Embase, Scopus, and Cochrane clinical trials database) and related journals up to September, 2020. A qualitative and quantitative synthesis was performed on data extracted from the included studies.

RESULTS

Three RCTs (number of patients = 120; number of dental implants = 120) and two prospective cohort studies (number of patients = 144; number of dental implants = 144) with one to three-year follow-up periods were included. The quantitative analyses did not demonstrate a significant difference between digitally customized and prefabricated abutments for peri-implant pocket depth (P = 0.62), plaque index (P = 0.67), bleeding on probing (P = 0.43), keratinized mucosa width (P = 0.75), and pink aesthetic score (P = 0.30) at one-year follow-up visit. The qualitative analyses for marginal bone level change, calculus accumulation, implant survival rate, implant success rate, white aesthetic score, and patient-reported outcomes did not demonstrate a significant difference between two groups during 1 to 3-year follow-up visits.

CONCLUSION

The current data do not provide evidence of significant differences between two abutment fabrication methods in terms of peri-implant clinical outcomes within short-term period (CRD42020170807).

Implant soft tissue Dehiscence coverage Esthetic Score (IDES): A pilot within- and between-rater analysis of consistency in objective and subjective scores

OBJECTIVES

To introduce an esthetic index for assessing the outcomes of peri-implant soft tissue dehiscence/deficiency (PSTD) coverage and test its within- and between-reviewer reliability.

MATERIALS AND METHODS

Photographs of 51 single PSTDs at baseline and after treatment were provided to four periodontists from three centers. The examiners were asked to rate each case at two timepoints with the Implant soft tissue Dehiscence/deficiency coverage Esthetic Score (IDES) that involved the evaluation of the post-treatment level of the soft tissue margin, peri-implant papillae height, mucosa color, and mucosa appearance (summing up to a total score of 10). Variance components analysis was conducted using multilevel regression fit in a Bayesian framework for obtaining uncertainty intervals for fractional variance contributions and intraclass correlation values (ICC) of the IDES, and for each of its four clinical variables.

RESULTS

Regression models showed reproducible esthetic evaluation among the examiners (inter-reliability) and negligible intra-reviewer variability (assessment of the same case at different timepoints). The ICC for the variability in the assessment of the overall IDES was 0.86, and for the individual components ranged from 0.78 to 0.87. Additionally, there was a strong similarity between the raters' IDES values, and their subjective esthetic response, by the same raters.

CONCLUSION

The IDES showed persistent judgment among the 4 reviewers, and only a slight intra-reviewer variability across timepoints. Within its limitations, this study suggests that the proposed novel score can be a reliable tool for evaluating the esthetic outcomes of PSTD coverage, which can aid in standardization of esthetic assessments following the treatment of a PSTD.

The peri-implant phenotype and implant esthetic complications. Contemporary overview

OBJECTIVE

To provide a contemporary and comprehensive overview of the hard and soft tissue biological structures surrounding an osseointegrated dental implant (peri-implant referred to as the peri-implant phenotype), in the context of peri-implant esthetic complications.

OVERVIEW

The individual components of the peri-implant phenotype (keratinized mucosa width, mucosal thickness, supracrestal tissue height, and the peri-implant buccal bone) have been linked to different aspects of implant esthetics, as well as health-related aspects. At the time of implant therapy, respecting the biology of the peri-implant hard and soft tissues, and anticipating their remodeling patterns can alleviate future esthetic complications.

CONCLUSIONS

While the current literature may not allow for a point-by-point evidence based-recommendation for the required amount of each peri-implant structure, bearing in mind the proposed values for the components of the peri-implant phenotype, at the time of and prior to implant therapy can lead to more predictable treatment outcomes, and the avoidance of esthetic complications.

CLINICAL SIGNIFICANCE

Knowledge of hard and soft tissue components surrounding and osseointegrated dental implant, and their underlying biological remodeling process is crucial for carrying out a successful therapy and alleviating possible future esthetic challenges.