Facial alveolar bone alterations and gray value changes based on cone beam computed tomography around maxillary anterior implants: A clinical retrospective study of 1-3 years

Clinical efficacy of a two-piece abutment conforming to the concept of one abutment one time in the posterior region: A clinical pilot study

OBJECTIVES

To assess the impact of a two-piece abutment workflow on enhancing the stability of the alveolar bone and gingiva surrounding the dental implant, and to determine the level of patient satisfaction.

MATERIALS AND METHODS

A total of 48 patients with dentition defect in the posterior region were included and divided into two groups: the two-piece abutment workflow (TAW) and the sealing screw with submerged healing workflow (SHW). Marginal bone level (MBL), soft tissue indicators, oral hygiene indicators, and patient satisfaction were assessed and recorded partially at 0, 3, 6, and 12 months after surgery. The primary outcome was the change of MBL in different time periods. A generalized linear mixed model (GLMM) was used to take into account the correlated nature of the data, and adjust for potential confounding factors within inter-group differences.

RESULTS

The survival rate of implants and prosthesis reached 100% at 12-month follow-up, with an average decrease of 0.25 mm (SD 0.23 mm) of MBL in the TAW group and 0.48 mm (SD 0.45 mm) in the SHW group. The change of MBL in the TAW group (0.15 ± 0.31 mm) was significantly lower than the SHW group (0.41 ± 0.41 mm) through the analysis of GLMM within 6 months, while no significance was found in 12 months. Moreover, less gingival pain and oppression during prosthesis loading, and less time consumption overall duration were showed in the TAW group through Visual Analogue Scale (VAS, p < 0.05).

CONCLUSIONS

Within a 6-month period, the two-piece abutment workflow showed superior efficacy in preserving the integrity of the marginal bone level. Furthermore, it streamlined treatment procedures and mitigated discomfort, hence increasing patient satisfaction.

Bone alteration and esthetics associated with implant-supported prostheses in the anterior maxilla under different implant placement timing: A retrospective clinical study of 1 to 3 years

STATEMENT OF PROBLEM

Different factors influence alterations in facial bone thickness and esthetic outcomes after implant placement. Whether the timing of implant placement influences alterations in the bone dimensional and esthetic outcomes is unclear.

PURPOSE

The purpose of this retrospective clinical study was to assess the influence of the timing of implant placement on alveolar bone alterations and esthetic outcome.

MATERIAL AND METHODS

Data were collected from 40 patients who had received guided bone regeneration (GBR) performed simultaneously with immediate, early, or delayed single-tooth implant placement in the anterior maxilla. Facial and palatal horizontal bone thicknesses (FHBT, PHBT) and vertical bone level (FVBL, PVBL) immediately after surgery (T0), at 6 months after implant placement (T1), and at 1 to 3 years follow-up (T2) were measured, and the changes calculated. The pink esthetic score (PES) and white esthetic score (WES) were evaluated at the 1- to 3-year follow-up. The Kruskal-Wallis followed by the Dunn t test was applied to evaluate bone alteration among groups, and the Bonferroni method was used for adjusting multiple comparisons. The 1-way ANOVA test was used to determine any significance in the esthetic outcome in the 3 groups (α=.05).

RESULTS

The reduction in the FHBT0 of the immediate, early, and delayed implant placement group (T2-T0) was -1.17 (-1.70, -0.61) mm, -1.53 (-1.69, -0.49) mm, and -1.47 (-2.30, -0.20) mm, respectively. The FHBT around the implant apices remained basically stable. No obvious changes in the PHBT around the implants of the immediate and delayed implant placement group were noted. The FVBL significantly decreased in each group during the follow-up period (-1.34 (01.88, -0.56) mm, immediate; -2.88 (-3.79, -1.07) mm, early; -1.26 (-2.52, -0.48) mm, delayed). The PVBL change in the early implant placement group (-2.18 (-3.26, -0.86) mm) was more significant than that in the immediate (-0.55 (-2.10, -0.17) mm) and delayed (-0.51 (-1.29, 0.02) mm) implantation groups (P =.013). The mean ±standard deviation PES/WES score of the immediate (15.6 ±1.84) and early (15.00 ±1.13) implant placement groups was higher than that of the delayed implant placement group (13.92 ±2.10) without significant difference.

CONCLUSIONS

Similar bone changes and esthetic outcomes were found around implants of the immediate, early, and delayed implant placement groups.

A nomogram prediction of implant apical non-coverage on bone-added transcrestal sinus floor elevation: A retrospective cohort study

OBJECTIVES

To identify the risk indicators and develop and validate a nomogram prediction model of implant apical non-coverage by comprehensively analyzing clinical and radiographic factors in bone-added transcrestal sinus floor elevation (TSFE).

MATERIAL AND METHODS

A total of 260 implants in 195 patients receiving bone-added TSFE were included in the study. The population was divided into a development (180 implants) and a validation (80 implants) cohort. According to 6 months post-surgery radiographic images, implants were categorized as "apical non-coverage" or "apical covered." The association of risk factors including clinical and radiographic parameters with implant apical non-coverage was assessed using regression analyses. A nomogram prediction model was developed, and its validation and discriminatory ability were analyzed.

RESULTS

The nomogram predicting bone-added TSFE's simultaneously placed implant's apex non-coverage after 6 months. This study revealed that sinus angle, endo-sinus bone gain, implant protrusion length, graft contact walls, and distal angle were predictors of implant apical non-coverage. The generated nomogram showed a strong predictive capability (area under the curve [AUC] = 0.845), confirmed by internal validation using 10-fold cross-validation (Median AUC of 0.870) and temporal validation (AUC = 0.854). The calibration curve and decision curve analysis demonstrated good performance and high net benefit of the nomogram, respectively.

CONCLUSIONS

The clinical implementation of the present nomogram is suitable for predicting the apex non-coverage of implants placed simultaneously with bone-added TSFE after 6 months.

Implant survival rate and marginal bone loss with the all-on-4 immediate-loading strategy: A clinical retrospective study with 1 to 4 years of follow-up

STATEMENT OF PROBLEM

Assessing peri-implant marginal bone loss (MBL) and its risk factors with cone beam computed tomography (CBCT) may clarify the risk factors for the all-on-4 (5 or 6) strategy and further improve its survival rate.

PURPOSE

The purpose of this retrospective clinical study was to evaluate the implant survival rate, MBL, and associated risk factors of all-on-4 (5 or 6) prostheses after 1 to 4 years of follow-up with CBCT.

MATERIAL AND METHODS

A total of 56 participants rehabilitated with 325 implants by using the all-on-4 (5 or 6) concept between October 2015 and December 2019 were included. Outcome measures were cumulative implant survival (life-table analysis) and MBL. Four CBCT scans, a scan immediately after surgery (T0), a scan 1 year after surgery (T1), a scan 2 years after surgery (T2), and a scan 3 to 4 years after treatment (T3), were obtained to evaluate the MBL. The Pearson correlation coefficient analysis and linear mixed models were performed to assess the potential risk factors for MBL (α=.05).

RESULTS

The implant survival rate was 99.38%, and the prosthesis survival rate was 100%. The reductions in the vertical buccal bone height (△VBBH) were 0.74 ±0.10 mm (T0-T1), 0.37 ±0.12 mm (T1-T2), and 0.15 ±0.14 mm (T2-T3). Except for T2-T3, the △VBBH showed a significant difference at T0-T1 and T1-T2 (P≤.05). The alterations in vertical mesial bone height (VMBH), vertical distal bone height (VDBH), and vertical lingual bone height (VLBH) were similar to the trend observed in VBBH. The △VBBH (T0-T3) was negatively correlated with the horizontal buccal bone thickness (HBBT) (T0) (r=-.394, P<.001). Linear mixed models revealed that factors such as smoking (P=.001), mandible implant site (P<.001), immediate implant (P=.026), tilted implant (P<.001), female sex (P=.003), systemic disease (P=.025), and bruxism (P=.022) negatively affected MBL. The cantilever length (CL) also had a negative effect on MBL around the implants at the distal extension (P<.001).

CONCLUSIONS

The high implant and prosthesis survival rates and low MBL confirmed the predictability of the all-on-4 (5 or 6) concept. Smoking, mandible implant site, systemic disease, bruxism, female sex, immediate implant, tilted implant, and CL were identified as potential risk factors for MBL.

Changes in bone graft height and influencing factors after sinus floor augmentation by using the lateral window approach: A clinical retrospective study of 1 to 2 years

STATEMENT OF PROBLEM

Recent systematic reviews have reported resorption of bone grafts after augmentation, but the influencing factors are numerous and uncertain. Different brands of bone graft and other factors may affect the bone formation effect after sinus floor augmentation.

PURPOSE

The purpose of this retrospective clinical study was to evaluate the graft material height changes after sinus floor augmentation with cone beam computed tomography (CBCT) and to investigate the potential influencing factors related to graft resorption.

MATERIAL AND METHODS

Four midsagittal cut CBCT images of 157 posterior maxillary implants after maxillary sinus floor elevation by using the lateral window approach with bone grafts from 116 patients were obtained. Four CBCT scans had been performed immediately (T0), 6 months (T1) and 12 months after bone grafting (T2), and 1.5 to 2 years after treatment (T3), and the distance between the implant platform and the grafted mucosa of the maxillary sinus floor was measured at 3 locations. Correlation coefficients of these parameters were calculated. A linear mixed model was used to investigate potential factors influencing graft height reduction, including the patient's sex, age, smoking status, periodontal status, graft brand, implant site, implant level, placement time, and residual bone height.

RESULTS

Mean ±standard deviation graft height at the mesial side of the implant (MeGH) was significantly decreased by 0.32 ±0.88 mm in the first 6 months, was gradually reduced after 6 months (0.26 ±0.43 mm), and then 1 to 2 years later increased to 0.39 ±0.97 mm. The changes in graft height at the center of the implant (CeGH) and graft height at the distal side (DiGH) groups were similar to those in the MeGH group. A significantly positive correlation was found among the height alterations in 3 locations (rs=0.954, P<.001). The linear mixed model showed that smoking was more likely to cause graft height reduction in MeGH (P=.034).

CONCLUSIONS

Graft height significantly decreased after maxillary sinus augmentation over 1 to 2 years. Smoking had a negative effect on graft height changes, while the 2 brands of graft and other factors had no significant effect.

Effectiveness and complications of transcrestal sinus floor elevation using the cushioned grind-out technique: A retrospective cohort study with up to 7 years of follow-up

AIM

To evaluate the effectiveness and complications of the cushioned grind-out technique. The primary outcome was endo-sinus bone gain (ESBG), while secondary outcomes included the Schneiderian membrane perforation rate and mid- to long-term implant survival.

MATERIALS AND METHODS

In this retrospective study, we compared the cushioned grind-out technique with the classic osteotome technique, establishing statistical models to assess ESBG, membrane perforation rate and implant survival rate.

RESULTS

A total of 259 patients and 340 implants were included. The mean ESBG was 5.31 mm for the cushioned grind-out group and 4.64 mm for the osteotome group. Multivariable regression analysis revealed that the cushioned grind-out technique significantly facilitated ESBG (p = .028). Nineteen preparation sites experienced membrane perforation, with rates of 5.5% and 6.4% for the cushioned grind-out and osteotome groups, respectively. However, the difference was not statistically significant (p = .920). Additionally, the cumulative survival rate of the implants for 7 years was 95.2% and 91.4%, respectively, with the surgical technique not significantly influencing the results.

CONCLUSIONS

With 6 months to 7 years of post-prosthetic restoration review data, our findings show that the cushioned grind-out technique facilitates a higher ESBG, with no significant difference in membrane perforation or implant failure rate.

Immediate implant placement with simultaneous bone augmentation versus delayed implant placement following alveolar ridge preservation: A clinical and radiographic study

OBJECTIVE

The present study aimed to evaluate the clinical and radiographic outcomes of immediate implant placement (IIP) with guided bone regeneration (GBR) as compared to delayed implant placement (DIP) following alveolar ridge preservation (ARP) and to identify the potential risk factors influencing these outcomes.

METHODOLOGY

A total of 56 patients (IIP = 28 vs. DIP = 28) with class I or II bony defects received 56 implants were included. GBR procedure using Bio-Oss® bone substitute mixed with advanced platelet-rich fibrin (A-PRF) and covered by Bio-Gide® membrane and additional A-PRF membrane was performed either simultaneously with the IIP or earlier at the time of ARP in DIP. Clinical and 3-D radiographic analyses of bone level, thickness, and density were performed at three-time intervals (T1, immediately; T2, 6-7 months; and T3, 1.5 to 2 years post-implantation), corresponding to the neck, coronal, middle, and apex of implants.

RESULTS

The survival rate was 100% in both groups. IIP showed significant favorable outcomes regarding distal marginal bone level (anterior maxilla, T1-T3) and neck and coronal horizontal facial bone thickness (HFBT) (posterior maxilla, T1; and anterior maxilla, T1-T3, respectively) compared to DIP. However, DIP showed significant facial bone density at the neck and coronal parts in the anterior maxilla (T1) and the coronal part in the posterior maxilla (T3). The facial marginal bone level change was positively correlated with HFBT change (P = 0.007), which is negatively correlated with the secondary implant stability (P = 0.019). The implant region (anterior or posterior maxilla) was the only factor affecting on Implant stability quotient value (ISQ) and change in HFBT (P ˂ 0.05).

CONCLUSION

Overall, the IIP combined with GBR in the post-extraction sites with pre-implant class I or II bony defects had some favorable outcomes compared to DIP after ARP. However, the clinical outcomes, ISQ value, and changes in bone level, thickness, and density from T1-T3 were comparable.

New Oral Surgery Materials for Bone Reconstruction-A Comparison of Five Bone Substitute Materials for Dentoalveolar Augmentation

This article presents a comparison of bone replacement materials in terms of their ability to produce living bone image at the place of their implantation. Five bone replacement materials are compared (Osteovit-porous collagen, Cerasorb Foam-collagen scaffolding of synthetic β tricalcium phosphate, Osbone-synthetic hydroxyapatite, Endobone-deproteinized bovine-derived cancellous bone hydroxyapatite, and Cerasorb-synthetic β tricalcium phosphate). Intraoral radiographs are taken immediately after implantation and 12 months later. The texture analysis was performed to assess (texture index, TI) the level of structure chaos (entropy) in relation to the presence of longitudinal elements visible in radiographs (run length emphasis moment). The reference ratio of the chaotic trabecular pattern (Entropy) to the number of longitudinal structures, i.e., trabeculae (LngREmph), is 176:100 (i.e., 1.76 ± 0.28). Radiological homogeneity immediately after the implantation procedure is a result of the similar shape of its particles (Osbone, Endobone and Cerasorb) or radiolucency (Osteovit, Cerasorb Foam). The particles visible in radiographs were similar in the LngREmph parameters applied to the reference bone, but not in the co-occurrence matrix features. The TI for Osteovit during a 12-month follow-up period changed from 1.55 ± 0.26 to 1.48 ± 0.26 (p > 0.05), for Cerasorb Foam from 1.82 ± 0.27 to 1.63 ± 0.24 (p < 0.05), for Osbone from 1.97 ± 0.31 to 1.74 ± 0.30 (p < 0.01), and for Endobone from 1.86 ± 0.25 to 1.84 ± 0.25 (p > 0.05), The observed structure in the radiological image of bone substitute materials containing calcium phosphates obtains the characteristics of a living bone image after twelve months.