The occurrence of peri-implant mucositis associated with the shift of submucosal microbiome in patients with a history of periodontitis during the first two years.

AIM: To investigate the dynamic changes of peri-implant microbiome in patients with a history of periodontitis and to construct a microbial prediction model. MATERIALS AND METHODS: The prospective study was performed at one month (T1), one year (T2) and two years (T3) after restoration. Clinical examinations [probing depth (PD), bleeding on probing (BOP), suppuration (SUP)], radiographic examinations and sample collection were conducted at three timepoints. Peri-implant sulcular fluid (PISF) was collected and analysed by 16S rRNA gene sequencing. Generalized linear mixed model (GLMM) was used to identify differences. RESULTS: Totally, 168 subjects were assessed for eligibility. Twenty-two patients were recruited in the longitudinal study. Eventually, 67 PISF samples from 24 implants of 12 patients were collected and analysed. Peri-implant microbiome showed increasing diversity and complexity over time. Disease-associated genera Porphyromonas, Tannerella, Treponema and Prevotella dramatically increased from T1 to T3. The prediction model for clinical suppuration at T1 showed a high accuracy of 90%. CONCLUSION: The dysbiosis of peri-implant microbiome increased with time during the two-year observation in patients with a history of periodontitis. Genera of Porphyromonas, Tannerella, Treponema and Prevotella were biomarkers of peri-implant mucositis. Microbiota at the early stage could predict subsequent microbial dysbiosis and clinical suppuration.

A three-year study on periodontal microorganisms of short locking-taper implants and adjacent teeth in patients with history of periodontitis.

OBJECTIVE: To analyze the change of six periodontal pathogens around short locking-taper implants and adjacent teeth in patients with different periodontal conditions for three years. METHODS: Sixty implants and 62 adjacent teeth from 24 patients with different periodontal conditions were included: 5 patients with history of aggressive periodontitis (AgP group), 14 patients with history of chronic periodontitis (CP group), and 5 patients with healthy condition or slight gingivitis (H group). Subgingival samples were collected at five timepoints: before implant placement (T1); before second stage operation (T2); one month after restoration (T3); one year after functional loading (T4) and two years after functional loading (T5). Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Fusobacterium nucleatum, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans were detected by polymerase chain reaction (PCR). RESULTS: Pathogens were hardly found around implants or adjacent teeth until T4. The detection rates of five pathogens other than A. actinomycetemcomitans raised up from T3 to T5. F. nucleatum and P. gingivalis were mostly detected followed by P. intermedia, T. forsythia, and T. denticola. The detection rate of P. gingivalis in implants were higher than natural teeth. There was significant correlation between pathogenic bacteria from implants and adjacent teeth. A. actinomycetemcomitans were only detected positively in peri-implant sites of AgP group. Peri-implantitis sites showed significantly higher detection rates of T. denticola, F. nucleatum at T4, and P. gingivalis, F. nucleatum at T5 than peri-implant mucositis and healthy groups. CONCLUSION: This three-year longitudinal study demonstrated that periodontal pathogens accumulate over time around short locking-taper implants and adjacent natural teeth after restoration. Adjacent teeth may become the microbial reservoir for peri-implant bacteria. Therefore, periodontally compromised patients may face higher risk for peri-implant disease. CLINICAL SIGNIFICANCE: Plaque control of implant should be intensified with time instead of diminished. Patients with history of periodontitis need more frequent and individualized implant maintenance. Treatment and maintenance for adjacent teeth is as important as for implants..

Ligature-induced peri-implant infection in crestal and subcrestal implants: a clinical and radiographic study in dogs.

Objective. The aim of this study was to assess the influence of implant-abutment interface (IAI) placement depths on peri-implant tissues in the presence of ligature-induced peri-implant inflammation. Materials and Methods. Two implants with screwed-in IAIs (SI) and two implants with tapped-in IAIs (TI) were inserted in one side of the mandible in six dogs eight weeks after tooth extraction. Four experimental groups were constituted: SI placed crestally, SI placed 1.5 mm subcrestally, TI placed crestally and TI placed 1.5 mm subcrestally. After 12 weeks, the healing abutments were connected. Four weeks later, cotton floss ligatures were placed around the abutments to promote plaque accumulation. Clinical and radiographic examinations were performed at 0, 6 and 12 weeks after ligature placement. The effects of the IAI placement depths on clinical and radiographic parameters were assessed. Results. The alterations of peri-implant probing depths, clinical attachment levels, distances from the IAI to the first bone-implant contact (IAI-fBIC) and depths of infrabony defect were significant larger in the subcrestal groups compared with the crestal groups during the plaque accumulation period. The alterations of clinical attachment levels, IAI-fBIC, depth of the infrabony defect and horizontal bone loss were not significantly different between the SI and TI groups after ligature placement. Conclusion. Tissue destruction in subcrestal implants may be more serious than that in crestal implants in the presence of inflamed peri-implant mucosa.

[Comparison of treatment effect between periodontal subgingival scaling with the special series of ultrasonic inserts and Gracey curette].

OBJECTIVE: To compare the special series of ultrasonic inserts with Gracey curettes in the effectiveness and efficiency for non-surgical periodontal treatment. METHODS: A total of 30 patients with moderate to advanced chronic periodontal disease were treated with both ultrasonic inserts (ultrasonic group) and Gracey curettes (Gracey group) according to a prospective, randomized, controlled, one-blind, "split-mouth" design. Twenty-six cases were available for the whole follow-up period. Plaque index (PLI), bleeding index(BI), probing depth (PD), attachment loss (AL) were evaluated before and 6 weeks after treatment. Treatment time was recorded. The severity of pain during treatment and teeth sensitivity after treatment were evaluated by the visual analogue scale (VAS). Differences in clinical parameters were analyzed with the Wilcoxon signed ranks test and Mann and Whitney U-test. RESULTS: No significant differences in any of the clinical parameters were observed at baseline between the two groups. The mean value of PD, BI, PLI, AL decreased in both ultrasonic group and Gracey group. At moderately deep site (initial PD between 4 mm and 5 mm), PD [M(Q(25), Q(75))] changed in the ultrasonic group from 4.0 (4.0, 4.5) mm to 3.0 (3.0, 3.0) mm (P < 0.001) and in the Gracey group from 4.0 (4.0, 5.0) mm to 3.0(3.0, 3.0) mm (P < 0.001). At deep sites (initial PD ≥ 6 mm) PD [M(Q(25), Q(75))] changed in the ultrasonic group from 7.0(6.0, 7.0) mm to 5.0(4.0, 7.0) mm (P < 0.001) and in the Gracey group from 7.0 (6.0, 7.0) mm to 5.0(4.0, 6.0) mm(P < 0.001). In the furcation area, PD [M(Q(25), Q(75))] changed from 5.0(4.0, 7.0) mm to 3.0(3.0, 5.0) mm (P < 0.001) in both Gracey group and ultrasonic group. However, the average time of active instrumentation was (2.41 ± 0.61) min/tooth in the ultrasonic scaling and (2.71 ± 0.61) min/tooth in the Gracey curette (P < 0.001). VAS scores [M(Q(25), Q(75))] of pain during treatment was 5.0(3.0, 6.7) in the ultrasonic group and 5.9 (4.9, 8.0) in the Gracey group (P = 0.001). VAS scores [M(Q(25), Q(75))] of sensitivity after treatment was 4.0 (1.8, 6.0) in the ultrasonic group and 4.9 (2.0, 8.0) in the Gracey group (P = 0.043). CONCLUSIONS: Treatment with the special series of ultrasonic inserts was as effective as the Gracey curette during initial therapy period in all clinical parameters measured and has the advantage of being quicker.

Influence of placement depth on bone remodeling around tapered internal connection implant: a clinical and radiographic study in dogs.

BACKGROUND: The aim of this study is to evaluate the influence of placement depth on bone remodeling around implants with two different types of tapered internal implant-abutment interface (IAI): tapped-in (TI) tapered internal IAI and screwed-in (SI) tapered internal IAI in dogs. METHODS: The second, third, and fourth premolars and the first molar in mandibles of six beagle dogs were extracted. After 8 weeks, two SI implants and two TI implants were placed in one side of the mandible. There were four experimental groups: 1) SI placed crestally (SIC); 2) TI placed crestally (TIC); 3) SI placed 1.5 mm subcrestally (SIS); and 4) TI placed 1.5 mm subcrestally (TIS). Healing abutments were connected 12 weeks after implant surgery. Implants and teeth were brushed every second day during the healing period. Clinical and radiographic parameters were recorded at 4, 10, and 16 weeks after second-stage surgery. RESULTS: Differences between SI and TI implants inserted in the same vertical position were not significant for peri-implant probing depth (PD), clinical attachment level (CAL), or bone resorption (P >0.05). Subcrestal placement of both implants had greater PD and CAL compared to crestal groups. However, distance from IAI to the first bone-implant contact was lower in subcrestal groups compared to crestal groups (1.27 ± 0.42 mm for SIC versus 0.46 ± 0.26 mm for SIS, P <0.05; 1.36 ± 0.31 mm for TIC versus 0.78 ± 0.42 mm for TIS, P <0.05). CONCLUSIONS: Tapered internal IAI configuration had no significant effect on crestal bone resorption. Moreover, subcrestal placement of tapered internal IAI had a positive impact on crestal bone preservation around the cervix of the implant.