Comparison of stress distribution around all-on-four implants of different angulations and zygoma implants: a 7-model finite element analysis

BACKGROUND

In recent years, zygomatic implants and the all-on-four treatment concept have been increasingly preferred for rehabilitation of atrophic maxillae. However, debate continues regarding the optimal configuration and angulation of the implants. The aim of this study was to analyze the biomechanical stress in implants and peri-implant bone in an edentulous maxilla with zygomatic implants and the all-on-four concept, using multiple implant configurations.

METHODS

A total of 7 models consisting different combinations of 4-tilted dental implants and zygomatic implants were included in the study. In each model, a total of 200 N perpendicular to the posterior teeth and 50 N with 45° to the lateral tooth were applied. A finite element analysis was performed for determination of stress distribution on implants and peri-implant bone for each model.

RESULTS

Higher stress values were observed in both cortical and trabecular bone around the 45°-tilted posterior implants in all-on-four models when compared to zygomatic implants. In cortical bone, the highest stress was established in an all-on-four model including 45°-tilted posterior implant with 4,346 megapascal (MPa), while the lowest stress was determined in the model including anterior dental implant combined with zygomatic implants with 0.817 MPa. In trabecular bone, the highest stress was determined in an all-on-four model including 30°-tilted posterior implant with 0.872 MPa while the lowest stress was observed in quad-zygoma model with 0.119 MPa. Regarding von Mises values, the highest stress among anterior implants was observed in an all-on-four model including 17° buccally tilted anterior implant with 38.141 MPa, while the lowest was in the including anterior dental implant combined with zygomatic implants with 20,446 MPa. Among posterior implants, the highest von Mises value was observed in the all-on-four model including 30°-tilted posterior implant with 97.002 MPa and the lowest stress was in quad zygoma model with 35.802 MPa.

CONCLUSIONS

Within the limits of the present study, the use of zygoma implants may provide benefit in decreasing biomechanical stress around both dental and zygoma implants. Regarding the all-on-four concept, a 17° buccal angulation of anterior implants may not cause a significant stress increase while tilting the posterior implant from 30° to 45° may cause an increase in the stress around these implants.

Promising results of surgical management of advanced medication related osteonecrosis of the jaws using adjunctive leukocyte and platelet rich fibrin

Background

Leukocyte- and platelet-rich fibrin (L-PRF) is an autologous matrix scaffold which regulates inflammation by stimulating cytokines and growth factors that are involved in the immune response. L-PRF is suggested as a viable adjunctive method to surgical interventions due to its advantages on tissue healing. This study aims to retrospectively evaluate the adjunctive role of L-PRF in surgically treated medication-related osteonecrosis of the jaws (MRONJ) patients.

Methods

Between January 2012 and December 2020, patients with AAOMS stage II and III MRONJ lesions, who were treated surgically with adjunctive use of L-PRF in the authors’ institution were enrolled. Surgical interventions consisted of either marginal resection or sequestrectomy with peripheral ostectomy (SPO) or curettage and L-PRF application. Medical records of these patients were retrospectively reviewed and healing was assessed according to certain parameters including mucosal closure and presence of infection, exposed bone, fistula or radiologic markers of disease progression for a minimum of 12 months.

Results

Thirteen patients (7 women and 6 men) with an average age of 72.4 years (± 10.61, range 54–84) were included in the study, nine of whom had AAOMS stage III and four stage II MRONJ. Three patients had a marginal resection, nine patients had sequestrectomy with peripheral ostectomy (SPO) and one patient underwent a curettage procedure. All marginal resection and six SPO patients showed complete healing while four patients, who had SPO or curettage experienced incomplete healing. Mean follow up was 20.1 ± 18.29 months.

Conclusion

The use of L-PRF may be a favorable adjunctive option in the treatment of MRONJ owing to its favorable effects on tissue repair, ease of application, minimally invasive and cost-effective character and autogenous nature.

Trial registration Retrospectively registered.

Extraoral approach to a bilateral unfavourable mandibular fracture under local anaesthesia: A case report

OBJECTIVE

To present a feasible treatment method for fractures of severely atrophic mandibles in high-risk patients undergoing general anaesthesia (GA).

CASE REPORT

A 77-year-old man presented with bilateral unfavourable fractures in an atrophic mandible. Pre-anaesthetic consultation revealed that the patient was at high risk for GA due to significant medical comorbid conditions of the patient, such as advanced age, chronic obstructive respiratory disease, diabetes mellitus and atherosclerosis. Thus, a modified treatment, consisting of open reduction and internal fixation using a combination of reconstruction plates and miniplates via an extraoral approach, was planned under local anaesthesia. The patient tolerated the surgical procedure well, without the need for sedation, and uneventful healing was achieved during postoperative period.

CONCLUSION

Local anaesthesia may be considered as the anaesthetic technique of choice when managing atrophic mandible fractures to reduce the risk of complications and shorten the time needed for recovery, especially in elders with significant medical comorbidities.

Evaluation of the course of the marginal mandibular branch of the facial nerve: a fresh cadaveric study

The aim of this study was to determine the course of marginal mandibular nerve (MMN) in relation to the inferior border of the mandible from the gonion until its terminal insertion to the depressor anguli oris, relating the position to a palpable anatomical landmark with emphasis on the depth of the nerve in relation to platysma and the deep cervical fascia. Twelve fresh adult cadavers were dissected and the mandibular base was contoured using needles with 5mm gaps, starting from the mandibular angle to the muscular termination point of the nerve bilaterally. The distance between the MMN and the mandibular base and total length of the nerve was measured bilaterally. The highest levels of MMN were measured 6.9mm and 6.5mm above, and the lowest levels were measured 4mm and 3mm below the mandibular base on right and left sides, respectively. The mean (SD) total length of the nerve until the muscular termination point was calculated 33.57 (3.41) mm on the right and 33.51 (4.88) mm on the left side. Previous publications that we had read all fell short of defining the schematic pathway of the nerve, as the described landmarks were of a combination of bone and soft tissue, which are not always clinically reliable. We have overcome this difficulty by standardising the inferior border of the mandible as a point in order to trace the marginal mandibular branch pathway. It originates along the gonion and ends at the second premolar tooth area.

Recurrent Aphthous Stomatitis as a Result of Zinc Deficiency

PURPOSE

The purpose of this study is to evaluate the results of patients, with a chief complaint of recurrent aphthous stomatitis (RAS), who were found to have zinc deficiency as the predisposing factor and received appropriate replacement therapy.

MATERIALS AND METHODS

A retrospective study was conducted using data from the medical records of patients with a chief complaint of RAS. Patients with potential ulcer-causing conditions were excluded. All patients were intraorally examined to rule out trauma-associated aetiologies. Blood tests were ordered to measure total blood count, serum transferrin, ferritin, zinc, folic acid and vitamin B12 levels.

RESULTS

A total of 48 patients, 34 with zinc deficiency and 14 with both zinc and iron deficiencies, were included in this study. Patients received an initial three-monthly replacement treatment and blood tests for the certain deficiencies were repeated at the end of this time interval. Two patients with zinc deficiency reported no relief due to incorrect intake of tablets with milk. Following correct instructions, all patients reached normal serum mineral levels and reported no recurrences. All patients remained asymptomatic and their mineral levels were monitored in every 3 months to detect any abnormalities. Overall mean follow-up for this study was 12.06 months (range: 8-28 months, SD: ± 5.7).

CONCLUSION

Zinc deficiency should be considered and investigated as part of the diagnostic process of RAS. A simple blood test may aid in correct diagnosis and complete resolution of this recurring condition rather than constant prescription of certain medicines to suppress the symptoms.

Proton pump inhibitor intake negatively affects the osseointegration of dental implants: a retrospective study

Objectives

This study sought to investigate the association between the systemic intake of proton pump inhibitors (PPI) and the early failure of dental implants.

Materials and Methods

A retrospective cohort study involving 1,918 dental implants in 592 patients (69 implants in 24 PPI users and 1,849 implants in 568 nonusers, respectively) was conducted. The effect of PPI intake on the osseointegration of dental implants was evaluated using patient- and implant-level models.

Results

Among 24 PPI users, two patients experienced implant failure, one of whom had three and the other of whom had one failed implant, respectively. Thus, the rate of failure for this population was 8.3%. Separately, 11 nonusers each experienced one implant failure, and the failure rate for these patients was 1.9%. Fisher's exact test revealed statistically significant differences between PPI users and nonusers at the implant level (P=0.002) but failed to show any significance at the patient level (P=0.094). The odds of implant failure were 4.60 times greater among PPI users versus nonusers. Dental implants that were placed in patients using PPIs were found to be 4.30 times more likely to fail prior to loading.

Conclusion

The findings of this study suggest that PPI intake may be associated with an increased risk of early dental implant failure.

Evaluation of the Efficacy of EDTA Chelation on Alveolar Bone Healing After Ultrasonic and Conventional Surgery Under Bisphosphonate Medication: A Rat Model

PURPOSE

The aims of the present study were 1) to investigate the effects of local ethylenediaminetetraacetic acid (EDTA) chelation on alveolar bone healing after systemic administration of bisphosphonates; and 2) to compare the healing in alveolar defects created with ultrasonic and conventional surgery.

MATERIALS AND METHODS

A total of 40 male Wistar rats were divided into 4 equal groups of 10 rats each (zoledronate and piezosurgery, zoledronate and bur, placebo and piezosurgery, and placebo and bur). The first 2 groups received weekly intraperitoneal injections of zoledronic acid (0.06 mg/kg), and the second 2 groups received saline solution for 4 weeks. After the last injections, horizontal defects 4 × 2 × 1 mm in size were created on the mandibular alveolar bone using piezosurgery or conventional bur surgery. The zoledronate groups received 10 minutes of local application of EDTA on 1 side and saline solution on the other side. In the placebo groups, only 1 side was treated (one half of the group with the bur and one half of the group with piezosurgery). All the rats were euthanized at 4 postoperative weeks for comparative histomorphometric evaluation of bone healing in the created defects.

RESULTS

Bone formation was found to be the greatest in the placebo groups (P < .05). Although a greater amount of bone formation was observed with piezosurgery and EDTA among the bisphosphonate-treated groups, the difference between the zoledronate groups was not statistically significant (P > .05). Similarly, no statistically significant difference was found between the use of piezosurgery and conventional bur surgery within the placebo groups (P > .05).

CONCLUSIONS

The findings of the present study revealed improved bone healing with the use of piezosurgery and EDTA chelation, although the difference did not reach statistical significance. Further research should be performed to clearly identify the role of EDTA as a chelating agent and in prevention of medication-related osteonecrosis of the jaws development.

Percutaneous treatment of orofacial vascular malformations

The aim of this study was to evaluate the efficacy of fluoroscopy-guided percutaneous injection of bleomycin as the primary treatment for low-flow vascular malformations. A total of 34 patients (mean (range) age 24 (8-51) years) with orofacial vascular lesions were treated in the Department of Interventional Radiology and Maxillofacial Surgery. There were 20 low-flow venous malformations, 11 lymphatic malformations, and three of mixed type. All patients were treated by fluoroscopy-guided percutaneous injection of a mixture of bleomycin (mean (range) 15 (5-15)mg) and a radio-opaque agent (Ultravist^® (iopromide), Bayer)/session. The number of sessions ranged from one to six. The clinical response was complete in 21 patients, obvious in nine, and of clinical benefit in four. Patients were reviewed within the first week, third week, and at three-month periods until 24 months. There were no serious complications such as pulmonary fibrosis. Fluoroscopy-guided intralesional injection of bleomycin should be considered as the first-line treatment for lymphatic malformations because it is effective and reliable with few complications.

Evaluation of temperature rise following the application of diode and ErCr:Ysgg lasers: an ex vivo study

Purpose

Erbium, chromium: yttrium, scandium, gallium, garnet (ErCr:Ysgg) lasers have been frequently used in oral surgical procedures and are almost seen as alternatives to diode lasers. The aim of this comparative study was to analyze in an animal model the thermal elevation induced by ErCr:Ysgg and diode lasers in soft tissue and bone.

Materials and methods

Thirty freshly dissected sheep mandibles containing bone and soft tissue were divided into 120 equal parts. Gallium-aluminum-arsenide (Ga-Al-As) diode laser (λ=940 nm) with 1, 2 and 5 W output powers and ErCr:Ysgg laser (λ=2780 nm) with 2.75, 4.5 and 6 W output powers were used on soft and bone tissues separately for 3 seconds with point application. Mean temperature values before and after application of the lasers were compared in soft tissue and bone.

Results

The minimum mean temperature value was observed with 2.75 W ErCr:Ysgg laser while irradiation with 5 W diode laser created the maximum values (p<0.05).

Conclusion

ErCr:Ysgg laser (λ=2780 nm) with 2.75 W power generates low levels of heat compared to diode lasers and may provide safer surgery in soft and bone tissues without destructive effects of temperature increase.

Esthetic evaluation of implant-supported single crowns: a comparison of objective and patient-reported outcomes

Background

This study investigated objective and patient-reported esthetic outcomes and their correlation for single-tooth implant restorations in the maxillary anterior region.

Methods

Nineteen patients were included. Gingival biotypes and smile lines were evaluated. Esthetic evaluation was performed according to the pink and white esthetic scores (PES and WES). Patients rated their satisfaction regarding the implant treatment using a subjective outcome questionnaire and a 10-cm visual analogue scale (VAS).

Results

The mean PES and WES were 10.7 (range 5–13, SD ± 2.24) and 8.6 (range 8–10, SD ± 0.60), respectively. The overall mean VAS was 8.54 ± 0.36 (range 3.8–9.8). No significant correlation was found between VAS and PES or WES (p = 0.475, p = 0.984, respectively). PES and WES scores for gingival biotypes failed to show any statistically significant difference (p = 0.701, p = 0.831). There was a significant negative correlation between the smile line and VAS; indicating that patients with lower smile lines expressed higher patient satisfaction (p = .001).

Conclusions

Professionally reported esthetic outcomes (PES and WES results) may not correlate with patient-reported outcomes. Smile line is a significant factor in patient satisfaction, which should be evaluated thoroughly prior to implant placement in the anterior maxilla.

Comparing the precision of panoramic radiography and cone-beam computed tomography in avoiding anatomical structures critical to dental implant surgery: A retrospective study

Purpose

The aim of this study was to evaluate the correlations between measurements made using panoramic radiography and cone-beam computed tomography (CBCT) based on certain anatomical landmarks of the jaws, with the goal of preventing complications due to inaccurate measurements in the pre-surgical planning phase of dental implant placement.

Materials and Methods

A total of 56 individuals who underwent panoramic radiography and a CBCT evaluation before dental implant surgery were enrolled in the study. Measurements were performed to identify the shortest vertical distance between the alveolar crest and neighboring anatomical structures, including the maxillary sinus, nasal floor, mandibular canal, and foramen mentale. The differences between the measurements on panoramic radiography and CBCT images were statistically analyzed.

Results

Statistically significant differences were observed between the measurements on panoramic radiography and CBCT for all anatomical structures (P<.05). The correlation coefficients (r) between the paired samples obtained from panoramic radiography and CBCT were closely correlated (P<.05), with r values varying from 0.921 and 0.979 for different anatomical regions.

Conclusion

The results of this study support the idea that panoramic radiography might provide sufficient information on bone height for preoperative implant planning in routine cases or when CBCT is unavailable. However, an additional CBCT evaluation might be helpful in cases where a safety margin cannot be respected due to insufficient bone height.

The potential clinical relevance of anatomical structures and variations of the maxillary sinus for planned sinus floor elevation procedures: A retrospective cone beam computed tomography study

BACKGROUND

Complications arising from sinus floor elevation (SFE) with lateral approach surgery can be avoided by means of maxillary sinus examination in the preoperative period.

PURPOSE

To investigate anatomical variations in the maxillary sinus by making use of cone beam computed tomography (CBCT) in terms of SFE with a lateral approach.

MATERIALS AND METHODS

Two hundred twenty eight maxillary sinuses in 114 patients were included. Parameters such as the position and diameter of the posterior superior alveolar artery (PSAA) canal, the frequency and localization of the septa or accessory maxillary ostium (AMO), and lateral wall thickness values were subjected to statistical analysis.

RESULTS

Septa were observed in 35.1% of sinuses. The majority of septa were determined in the middle region (48.8%). Additionally, 71.1% of PSAA canals were intraosseous, generally exceeding 1 mm in diameter (68.9%). The shortest mean perpendicular distance between the sinus floor and the PSAA canal was determined in the first molar region (9.22 ± 5.66 mm). Similarly, the highest mean sinus lateral wall thickness was determined in the first molar region, in the area 3 mm distant from the sinus floor (2.42 mm ± 0.88 mm). AMO was detected in 40.8% of sinuses.

CONCLUSION

CBCT-guided treatment planning may be beneficial prior to SFE procedures in order to avoid surgical complications.

Does the Intake of Selective Serotonin Reuptake Inhibitors Negatively Affect Dental Implant Osseointegration? A Retrospective Study

The success of osseointegration is influenced by several factors that affect bone metabolism and by certain systemic medications. Selective serotonin reuptake inhibitors (SSRIs) have been previously suggested to be among these medications. This study aims to investigate the association between systemic intake of SSRIs and failure of osseointegration in patients rehabilitated with dental implants. A retrospective cohort study was conducted, including a total of 2055 osseointegrated dental implants in 631 patients (109 implants in 36 SSRI \users and 1946 in 595 nonusers). Predictor and outcome variables were SSRI intake and osseointegration failure, respectively. The data were analyzed with Mann–Whitney test or Fisher exact test accordingly. Both patient-level and implant-level models were implemented to evaluate the effect of SSRI exposure on the success of osseointegration of dental implants. Median duration of follow-up was 21.5 months (range = 4–56 months) for SSRI users and 23 months (range –60 months) for nonusers (P = .158). Two of 36 SSRI users had 1 failed implant each; thus, the failure rate was 5.6%. Eleven nonusers also had 1 failed implant each; thus, the failure rate was 1.85%. The difference between the 2 groups failed to reach statistical significance at patient and implant levels (P = .166, P = .149, respectively). The odds of implant failure were 3.123 times greater for SSRI users compared with nonusers. Patients using SSRIs were found to be 3.005 times more likely to experience early implant failure than nonusers. The results of this study suggest that SSRIs may lead to increase in the rate of osseointegration failure, although not reaching statistical significance.

The effects of irrigation volume to the heat generation during implant surgery

Background

To evaluate the effects of the amount of irrigation on heat generated during implant site preparation.

Material and Methods

Ten freshly dissected sheep mandibles were sectioned into 30 equal bone blocks and transferred into a heat-controlled water tank. Implant socket preparations were performed with four consecutive drills. Temperature measurements were performed with a thermocouple inserted into the bone immediately before the preparation and after the drilling using three different physiologic saline irrigation set-ups: 1- No irrigation, 2- 12 ml/min and 3- 30 ml/min irrigation volume. The temperature differences between three different irrigation set-ups for implant drills 1, 2, 3 and 4, and the temperature differences between the drills for three different irrigation set-ups were separately compared.

Results

The temperature difference of no irrigation group was significantly higher than 12 ml/min and 30 ml/min groups for all four drills (p<0.05), whereas no statistically significant difference was found between 12 ml/min and 30 ml/min irrigation groups. (P >0.05) The temperature difference of drill 1 is significantly higher than drills 2, 3 and 4 for no irrigation group. (P <0.05) The temperature differences of drill 1, 2 and 3 were significantly higher than the temperature difference of drill 4 for 12 ml/min irrigation group. (p<0.05).

Conclusions

The heat generated during drilling is not directly proportional to the coolant volume. Given that certain amount of irrigation is applied, implant sites can be prepared safely without the need for additional irrigation, which may result in reduced visibility of the surgical site and therefore a suboptimal surgery.

Key words:Dental implants, irrigation, heat generation, drilling.

Comparison of the efficiency of irrigation of single and double-needle techniques of temporomandibular joint arthrocentesis: A cadaver study

OBJECTIVE

To compare the efficacy of the double- and single-needle arthrocentesis techniques in removing methylene blue from the temporomandibular joint (TMJ) space.

METHODS

This study was performed in 20 TMJs from 10 fresh cadavers. A total of 1 ml of 10 μM methylene blue solution was injected into the upper joint spaces, just prior to irrigation. Ten arthrocentesis procedures were carried out using the double-needle technique, and the remaining 10 were completed using the single-needle technique. The photo-absorbance values of methylene blue solution injected into and removed from the joint space were measured at a 665 nm wavelength. Statistical analysis was performed using Shapiro-Wilks test and t-test.

RESULTS

The t-test analysis showed no statistically significant difference between the two methods in the removal of methylene blue.

CONCLUSION

According to the results of the present study, the single-needle technique may be a good alternative with the advantages of easier application in cases where it is not possible to perform the double-needle technique.

The efficacy of Er,Cr:YSGG laser supported periodontal therapy on the reduction of peridodontal disease related oral malodor: a randomized clinical study

Background

This study aims to evaluate the efficacy of Er,Cr:YSGG laser assisted periodontal therapy on the reduction of oral malodor and periodontal disease.

Methods

Sixty patients with chronic periodontitis were included in the study and allocated into two groups each containing 30 patients. The study was planned in a double blind fashion. Conventional periodontal therapy was performed in group 1 and conventional periodontal therapy was performed in association with Er,Cr:YSGG application in group 2. Periodontal parameters of probing depth, clinical attachment level, plaque index and bleeding on probing were measured with a periodontal probe. Quantitative analysis of volatile sulphure compunds (VSCs) were measured with a calibrated halimeter at baseline level and at post-treatment 1st, 3rd and 6th months. P values <0.05 were accepted as statistically significant.

Results

There was a statistical significant reduction in VSC values in group 2 at post-treatment 3rd and 6th months (p < 0.05). Pocket depth values at post-treatment 1st month and bleeding on probing values at post-treatment 3rd and 6th months were significantly decreased in group 2 (p < 0.05). Intragroup statistical analysis revealed that there were statistically significant differences for all parameters (p < 0.01).

Conclusions

Er,Cr:YSGG laser assisted conventional periodontal therapy is more effective in reducing oral malodor and improving periodontal healing compared to conventional periodontal therapy alone.