Mini-implant mandibular overdentures under a two-step immediate loading protocol: A 4-6-year retrospective study.

OBJECTIVES: This retrospective study to evaluate the treatment outcomes of mandibular mini-implant overdentures (MIODs) placed under a two-step immediate loading protocol. BACKGROUND: The mini-implant overdenture emphasises the advantages of simplicity using flapless surgery and immediate loading. However, some mini-implant have lowe initial stability. MATERIALS AND METHODS: A total of 30 participants who used mandibular MIODs and maxillary removable complete dentures (RCDs) over 4 years were included. Four one-piece mini-implants (<3 mm in diameter) were placed by a flapless surgical approach after fabrication of new RCDs, and the O-ring attachment was attached at least 8 weeks after implant placement. RESULTS: The average observation period was 58.9 ± 9.2 months after mini-implant loading. The survival rate of the implants was 100.0%, and the overall change in mean marginal bone level (ΔMBL) was -0.9 ± 1.1 mm. The implant success rate was 83.3% at the implant level, and 66.7% at the patient level. The mean initial Periotest value was 0.9 ± 3.1, and it was positively associated with ΔMBL and implant success (P < .05). Patient satisfaction improved after conversion from RCDs to MIODs (P < .05), and mastication and pain showed greater satisfaction with longer loading time (P < .05). CONCLUSIONS: The mandibular MIODs could be chosen as an alternative treatment under a two-step immediate-loading protocol in edentulous patients with limited alveolar bone volume. To ensure superior treatment outcomes of MIODs, initial stability of implant must be obtained using as wide a diameter as possible within the anatomically allowable limits.

Complications of total temporomandibular joint replacement: a systematic review and meta-analysis.

The aim of this systematic review was to determine the most prevalent complications resulting from total temporomandibular joint (TMJ) replacement. An electronic search was performed using the Embase, LILACS, MEDLINE (via PubMed), SciELO, Scopus, and Web of Science databases up to June 2022. Prospective and retrospective clinical studies on patients who underwent TMJ replacement were included. Two reviewers performed the study selection, data extraction, and individual risk of bias assessment using the Joanna Briggs Institute Critical Appraisal Tools. The pooled prevalence of each complication was calculated through a proportion meta-analysis using the random-effects model. Twenty-eight studies met the eligibility criteria and were included in the review. All of the eligible studies had a low risk of bias. The results of the meta-analysis revealed that the most prevalent complication was paresis or paralysis of the facial nerve branches (7.8%; 95% confidence interval (CI) 2.6-15.1%, I2 = 94.5%), followed by sensory alterations (1.8%; 95% CI 0.6-4.9%, I2 = 88.8%), heterotopic bone formation (1.0%; 95% CI 0.1-2.5%, I2 = 75.8%), and infection (0.7%; 95% CI 0.1-1.6%, I2 = 22.7%). In conclusion, TMJ replacement has a low prevalence of complications, and most of them can be managed successfully.

Combination of surgical techniques and reconstructive devices as an alternative treatment after fibula free flap mandibular reconstruction failure: a case report

Loss of mandibular continuity and functionality in cancer patients undergoing extensive mandible resections is challenging. In these situations, the gold standard treatment is fibula free flap reconstruction. The major challenge occurs when there is a failure of the transplanted fibula. Here we report the case of a patient who underwent right hemimandibulectomy with disarticulation and immediate mandibular reconstruction with a fibula free flap. Subsequently, the flap viability was lost, and there was necrosis of the transplanted bone segment in the short-term follow-up. Considering the best form of rehabilitation for the patient, minimizing the risks of loss and optimizing the reconstructive quality, we opted to install a customized prosthesis including a condylecavity joint component associated with a new free flap and subsequent rehabilitation of the dental occlusion with an implant-supported fixed prosthesis.

Fatores associados ao interesse de usuários de prótese total mandibular em terapia implantossuportada e impacto da reabilitação com sobredentadura com implante único / Factors associated with the interest of users of complete mandibular dentures in implant-supported therapy and the impact of rehabilitation with single-implant overdentures

Este estudo objetivou identificar os fatores que influenciam na decisão de substituir uma prótese total convencional mandibular pelo tratamento com implantes dentários, assim como avaliar a satisfação, qualidade de vida e performance mastigatória (PM) após reabilitação com sobredentaduras com implante único (SIU) em pacientes adaptados e não-adaptados a prótese total convencional (PT) mandibular. Inicialmente, foi realizado um estudo transversal com 117 usuários de PTs bimaxilares, avaliados quanto aos desfechos relacionados à prótese (número de PTs mandibulares usadas previamente, tempo de uso e profissional que confeccionou a prótese atual, e quanto ao uso regular ou não da prótese mandibular) e aspectos centrados no paciente (período de edentulismo mandibular, altura óssea mandibular e interesse do paciente em se submeter a terapia com implantes). Do total da amostra, 78 pacientes manifestaram interesse na terapia implantossuportada, e desses apenas 22 foram selecionados e reabilitados com novas PTs bimaxilares. Após critérios de elegibilidade, foram alocados após pareamento em 2 grupos: adaptados à prótese mandibular (Grupo PTA - "adaptados à PT mandibular", n:10) e não adaptados (Grupo PTN - "não adaptados à PT mandibular", n:12). Em cada paciente, foi instalado um único implante na linha média e após o período de osseointegração as próteses mandibulares foram convertidas em sobredentaduras. O desempenho mastigatório foi avaliado pelo método das tamises, a altura óssea mandibular por medição em radiografia panorâmica, satisfação por escala quantitativa com questionário validado e o impacto da saúde oral na qualidade de vida pelo questionário OHIP-Edent-19. O teste Qui-quadrado foi utilizado para análise dos dados e as razões de prevalência ajustadas por meio da regressão multivariada de Poisson no primeiro estudo; para o segundo, a análise estatística em cada grupo e entre grupos foi baseada nos testes não-paramétricos de Wilcoxon e Mann-Whitney. O intervalo de confiança para os testes foi de 95%. A amostra foi predominantemente do sexo feminino, com 66,7% (n=78) dos participantes interessados em PT mandibular implantossuportada e com idade média de 65,68±6,38 anos. A PM não influenciou a escolha pela reabilitação com implantes. A preferência pela PT implantossuportada mandibular foi associada significativamente com maior experiência prévia com PT mandibular (p=0,021) e à insatisfação quanto à retenção (p=0,005). Após a intervenção com implante, todos os pacientes não adaptados passaram a condição de adaptados. Não houve diferença entre PTA e PTN para OHIP-Edent (p=0,276) e PM (p=0,222), a satisfação foi significativa apenas para o critério "conforto em arco inferior" (p=0,043). Para comparações pré e pós-tratamento com sobredentadura, a mediana do OHIP-Edent total diminuiu significativamente em ambos os grupos. Na comparação intragrupo, essa redução foi significativa em PTA apenas para a "limitação funcional" (p=0,026), e em PTN em quase todos os domínios, exceto "disfunção social" e "incapacidade" (p>0,05). Houve aumento estatisticamente significativo para a satisfação geral de 75,41 para 90,25 (p=0,012) em PTN e de 76,10 para 90,50 (p=0,007) em PTA. Os parâmetros "mastigação", "adaptação", "retenção" e "conforto" em arco inferior foram diferentes com significância em ambos os grupos, e "gustação", "fonação" e "dor" em arco inferior foram significativos apenas para o grupo não adaptado (p<0,05). Houve diferença significativa para PM em PTN (p=0,002) e PTA (p=0,047) ao se comparar tipo de reabilitação. Não houve correlação entre PM e OHIP antes e após a reabilitação (p>0,05). Pode-se concluir que a experiência prévia com PT mandibulares convencionais e a insatisfação com a retenção dessas, influenciam o interesse pela reabilitação com sobredentadura implantossuportada mandibular, assim como, a reabilitação com sobredentadura sobre implante único apresenta-se como alternativa aos pacientes não adaptados a PT convencional mandibular, auxiliando na aceitação do uso da prótese mandibular, assim como, comprovando efeito positivo na satisfação, qualidade de vida e performance mastigatória (AU).

This study aimed to identify the factors that influence the decision to replace a conventional mandibular complete denture by treatment with dental implants, as well as to evaluate satisfaction, quality of life and masticatory performance (MP) after rehabilitation with overdentures with a single implant in patients adapted and not adapted to conventional mandibular complete denture (CD). Initially, a cross-sectional study was carried out with 117 users of bimaxillaries CDs, who were evaluated for outcomes related to the denture (number of previous mandibular CDs, time of use and professional who made the current denture, and regarding regular use of the mandibular denture) and aspects centered patients (period of mandibular edentulism, mandibular bone height and the patient's willingness to undergo implant therapy). From the total sample, 78 patients expressed interest in implant-supported therapy, and of these, only 22 were selected and rehabilitated with new bimaxillary CDs. After eligibility criteria, they were allocated after pairing into 2 groups: adapted to mandibular prosthesis (PTA Group - "adapted to mandibular CD", n:10) and non-adapted (PTN Group - " not adapted to mandibular CD", n:12). In each patient, a single implant was installed in the midline and after the osseointegration period, the mandibular prostheses were converted into overdentures. Masticatory performance was evaluated by the sieve method, mandibular bone height by paranoid radiographic measurement, satisfaction by quantitative scale with a validated questionnaire and the impact of oral health on quality of life by the OHIP-Edent-19 questionnaire. The chi-square test was used for data analysis and the prevalence ratios adjusted by means of multivariate Poisson regression in the first study; on the second, the statistical analysis in each group and between groups was based on the non-parametric-Wilcoxon and Mann-Whitney tests. The confidence interval for the tests was 95%. The sample was composed predominantly by women, with 66.7% (n=78) of the participants interested in implantsupported mandibular CD, with mean age 65.68±6.38 years. MP was not influenced by the choice by dental implants rehabilitation. Preference for mandibular implant-supported CD was significantly associated with longer previous experience in mandibular CD (p=0.021) and with dissatisfaction regarding retention (p=0.005). After the implant intervention, all non-adapted patients became adapted. There was no difference between PTA and PTN for OHIP-Edent (p=0.276) and MP (p=0.222), satisfaction was significant only for the criteria "comfort in the lower arch" (p=0.043). For pre- and post-treatment comparisons with overdentures, the median total OHIP-Edent decreased significantly in both groups. In the intragroup comparison, this reduction was significant in PTA only for "functional limitation" (p=0.026), and in PTN in almost all domains, except "social dysfunction" and "disability" (p>0.05). There was a statistically significant increase in overall satisfaction from 75.41 to 90.25 (p=0.012) in PTN and from 76.10 to 90.50 (p=0.007) in PTA. The parameters "chewing", "adaptation", "retention" and "comfort" in the lower arch were significantly different in both groups, and "gustation", "phonation" and "pain" in the lower arch were significant only for the group not adapted (p<0.05). There was a significant difference for MP in PTN (p=0.002) and PTA (p=0.047) when comparing the type of rehabilitation. There was no correlation between MP and OHIP before and after rehabilitation (p>0.05). It can be concluded that the previous experience with conventional mandibular CD and the dissatisfaction with the retention of these, influence the rehabilitation with mandibular implant-supported overdenture, as well as the rehabilitation with overdenture on single implant presents itself as an alternative for patients not adapted to mandibular conventional CD, helping to accept the use of mandibular prosthesis, as well as proving a positive effect on satisfaction, quality of life and masticatory performance (AU).

A Novel Design Method of Gradient Porous Structure for Stabilized and Lightweight Mandibular Prosthesis.

Compared to conventional prostheses with homogenous structures, a stress-optimized functionally gradient prosthesis will better adapt to the host bone due to its mechanical and biological advantages. Therefore, this study aimed to investigate the damage resistance of four regular lattice scaffolds and proposed a new gradient algorithm for stabilized and lightweight mandibular prostheses. Scaffolds with four configurations (regular hexahedron, regular octahedron, rhombic dodecahedron, and body-centered cubic) having different porosities underwent finite element analysis to select an optimal unit cell. Meanwhile, a homogenization algorithm was used to control the maximum stress and increase the porosity of the scaffold by adjusting the strut diameters, thereby avoiding fatigue failure and material wastage. Additionally, the effectiveness of the algorithm was verified by compression tests. The results showed that the load transmission capacity of the scaffold was strongly correlated with both configuration and porosity. Scaffolds with regular hexahedron unit cells can withstand stronger loads at the same porosity. The optimized gradient scaffold showed higher porosity and lower maximum stress than the target stress value, and the compression tests also confirmed the simulation results. A mandibular prosthesis was established using a regular hexahedron unit cell, and the strut diameters were gradually changed according to the proposed algorithm and the simulation results. Compared with the initial homogeneous prosthesis, the optimized gradient prosthesis reduced the maximum stress by 24.48% and increased the porosity by 6.82%, providing a better solution for mandibular reconstruction.

The method of determining oral implantation sites based on an anatomical model of mandibular premolar area of a Beagle dog / 中国基层医药

Objective:To investigate the method of determining oral implantation sites based on an anatomical model of mandibular premolar area of a Beagle dog.Methods:This study was performed in the Second Affiliated Hospital of Zhejiang Chinese Medical University between January 2019 and October 2020. Mandibular anatomical structure and measurement data were compared between before and after removal of premolar teeth to determine safe implantation areas and oral implantation sites.Results:Among all mandibular premolars, the roots of the 1 st to 4 th premolars (P1-P4) gradually increased. The diameter of the mesial roots of the double root teeth P2, P3, and P4 was (2.72 ± 0.45) mm, (3.22 ± 0.32) mm, (4.16 ± 0.34) mm, respectively, which was significantly shorter than those in the distal roots [P2: (2.98 ± 0.29) mm, P3: (3.48 ± 0.27) mm, P4: (4.58 ± 0.22) mm]. The length of distal roots P2, P3 and P4 was (8.79 ± 0.41) mm, (9.21 ± 0.31) mm, (10.12 ± 0.36) mm), respectively, which was significantly shorter than that of mesial root [P2: (8.91 ± 0.69) mm, P3: (9.48 ± 0.27) mm, P4: (11.58 ± 0.24) mm]. Among all mandibles, the distance (H) from the mental foramen to the first molar and the width (W) of the alveolar crest increased successively [H1: (7.24 ± 0.49) mm, H2: (8.28 ± 0.71) mm, H3: (9.52 ± 0.37) mm, W1: (5.71 ± 0.81) mm, W2: (5.82 ± 0.28) mm, W3: (6.72 ± 0.54) mm]. Conclusion:The mental foramen and the distal part outside the canine apical area are safe implantation areas. In the safe implantation area, the length and diameter of the implant prosthesis do not exceed the root length in the implantation area and the maximum diameter in the buccal lingual direction.

Elastic deformation of the mandibular jaw revisited-a clinical comparison between digital and conventional impressions using a reference.

OBJECTIVES: Due to the partly strongly differing results in the literature, the aim of the present study was to investigate a possible deformation of the mandible during mouth opening using an intraoral scanner (IOS) and a conventional impression for comparison with a reference aid. MATERIALS AND METHODS: Four steel spheres were reversibly luted in the mandibular (n = 50) with a metallic reference aid at maximum mouth opening (MMO). Two digital impressions (Trios3), at MMO and at slightly mouth opening SMO and a conventional impression (Impregum), were taken as the measuring accuracy of the reference structure was already known. Difference between MMO-SMO for digital impressions and deviations between digital and conventional (SMO) were calculated. Furthermore, the angle between the normal vectors of two constructed planes was measured. Statistical analysis was performed with SPSS25. RESULTS: Deviations for linear distances ranged from -1 ± 3 µm up to 17 ± 78 µm (digital impressions, MMO-SMO), from 19 ± 16 µm up to 132 ± 90 µm (digital impressions, SMO), and from 28 ± 17 µm up to 60 ± 52 µm (conventional impressions, SMO). There were no significant differences for digital impressions (MMO-SMO), and there were significant differences between the conventional and digital impressions at SMO. CONCLUSIONS: Based on the results of the present study, no mandibular deformation could be detected during mouth opening with regard to the digital impressions. The results were rather within the measuring tolerance of the intraoral scanner. CLINICAL RELEVANCE: Based on the present study, no deformation of the mandibular during mouth opening could be observed at the level previously assumed. Therewith related, dental techniques related to a possible mandibular deformation therefore should be reconsidered.

Oral rehabilitation following fasciocutaneous free-flap reconstruction: A retrospective study.

AIM: The aim of this study is to retrospectively, observe a consecutive series of patients with segmental mandibulectomy defects reconstructed with fasciocutaneous free flaps and mandibular resection prostheses, and to review treatment concepts for the management of such patients. SETTINGS AND DESIGN: Observational study done at Memorial Sloan Kettering Cancer Center, New York, NY, USA. MATERIALS AND METHODS: Records were reviewed of all patients who had fasciocutaneous free-flap reconstruction and fabrication of mandibular resection prostheses following segmental mandibulectomy between 2000 and 2017 at a tertiary cancer center. Mandibular resection prosthesis fabrication interval data, as well as follow-up interval data, were recorded. STATISTICAL ANALYSIS USED: Descriptive statistics. RESULTS: Twenty-one consecutive patients had mandibular resection prostheses fabricated following segmental mandibulectomy and fasciocutaneous free-flap reconstruction during the study. The median time for mandibular resection prosthesis delivery following surgery was 9 months (range 4-41 months). There was a median of two-follow-up visits (range 0-4) within the first 90 days of mandibular resection prosthesis delivery. CONCLUSIONS: Oral rehabilitation with mandibular resection prosthesis following segmental mandibulectomy and fasciocutaneous free-flap reconstruction is an attainable treatment goal for the oncologic patient. Reviewing the proposed course of care is helpful for patient management.

Measuring the retention of removable mandibular prostheses by a standardized model: A technical report.

Three cases of mandibular implant overdentures (IODs) were measured for retention by a developed model. A nylon thread was tied through a hole at the midline of the IOD and seated it in the patient's mouth properly. Briefly, a facebow was set on the patient, with its arms firmly held by an assistant. The other end of the thread was tied into a loop, and the thread was inserted through a hole at the Camper's line of the facebow and hooked onto a portable force gauge. The thread was then pulled in parallel with the arms of the facebow by the force gauge until the prosthesis dislodged while the patient opened his mouth. Denture retention was measured five times, and the mean was calculated. Appropriate analysis for validity and reliability of the model was performed, and statistical results showed that it was valid and reliable for measuring the retention of removable mandibular prostheses.

A within-subject clinical trial on the conversion of mandibular two-implant to three-implant overdenture: Patient-centered outcomes and willingness to pay.

OBJECTIVES: To examine the impact of adding a third midline implant with stud attachment to a mandibular two-implant overdenture on patient-oriented outcomes. METHODS: In this pre-post design clinical trial, following the standard procedures, mandibular two-implant overdentures of 17 edentulous individuals (61.9 ± 6.6 years) were converted to three-implant overdentures by adding a stud attachment to an unloaded midline implant. Patient-oriented outcomes included patient expectations and satisfaction with implant overdenture as well as willingness to pay the cost of conversion. Data were collected at baseline and at the 6-week follow-up using visual analog and binary scales as well as open-ended questions. Statistical analysis included descriptive statistics, Spearman's correlation, Fisher exact test, Mann-Whitney U test, and the exact sign test. RESULTS: After connecting the third midline implant to the mandibular two-implant overdenture, there was a statistically significant decrease in the anteroposterior movement (p = 0.005) as evaluated by clinicians. Moreover, study participants reported an increase in perceived stability of the overdenture (95% CI; 0.68-1.00, p = 0.002) and in their ability to speak (95% CI; 0.63-1.00, p = 0.008). The addition of a third implant met the expectations of 94% of patients in regard to lower denture stability, 100% for retention, and 82.4% for comfort. The mandibular three-implant overdenture increased patient general satisfaction over a short period of time, but this improvement was not statistically significant. About 80% of patients would recommend this type of prosthesis to their peers but only 47% of them would agree to pay a large increase in the cost of treatment compared to a two-implant overdenture. CONCLUSIONS: The addition of a midline third implant to an existing mandibular two-implant overdenture resulted in several improved patient-reported outcomes.

A 30-Year Follow-Up of a Patient with Mandibular Complete-Arch Fixed Implant-Supported Prosthesis on 4 Implants: A Clinical Report.

Mandibular complete-arch fixed implant-supported prostheses are recognized as one of the earliest and most popular prostheses in implant dentistry. This prosthesis was the main focus in the early era of osseointegration. Despite its widespread popularity, few clinical reports have described long-term follow-up greater than 10 years for this type of prosthesis. This report describes a 30-year follow-up of a patient who underwent treatment for a mandibular complete-arch fixed implant-supported prosthesis with 4 machined surfaced implants, opposing a maxillary complete denture. This report documents a variety of photographs and radiographs taken over a period of 30 years to compare bone levels at various stages of care and maintenance, including de novo bone formation underneath the distal cantilevers due to functional loading. The biologic and biomechanical response to this treatment protocol and long-term clinical observations and prosthodontic outcome and maintenance needs are also addressed.

Mandibular reconstruction using customized three-dimensional titanium implant.

Mandibular defects lead to severe deformation and functional deficiency. Vascularized osteocutaneous tissue has been widely used to reconstruct the mandible. However, it is technically challenging to shape this type of grafts in such a manner that they resemble the configuration of the mandible. A 48-year-old female patient who underwent anterolateral thigh (ALT) flap coverage after a tongue cancer excision was diagnosed with a tumor recurrence during the follow-up. A wide excision mandibulectomy and mandibular reconstruction with an ALT flap and a titanium implant were performed. The prefabricated titanium implant was fixed to the condyle. Then, an ALT flap was harvested from the ipsilateral thigh and anastomosed. After confirming that the circulation of the flap was intact, the implant was fixed to the parasymphysis. On the radiograph taken after the surgery, the prosthesis was well positioned and overall facial shape was acceptable. There was no postoperative complication during the follow-up period, 1 year and 2 months. The prefabricated implant allows the restoration of facial symmetry without harvesting autologous bone and it is a safe and effective surgical option for mandibular reconstruction.

Temporomandibular joint reconstruction after condylar fracture complication related to osteosynthesis material.

Total condylar resorption and the failure of bone synthesis material as postoperative complications of condyle fracture are seldom reported in the literature. When these occur, they may severely limit temporomandibular joint (TMJ) function. In such cases, a reconstruction of the joint is indicated, which can be achieved by means of an alloplastic prosthesis. This article reports a rare case of impaction of osteosynthesis material in the region of the base of the skull associated with a mandibular condyle fracture treated with rigid internal fixation, which resulted in complications. There was progression to condylar resorption, requiring an alloplastic TMJ reconstruction, which was performed in a single surgical session.

Mandibular reconstruction using customized three-dimensional titanium implant

Mandibular defects lead to severe deformation and functional deficiency. Vascularized osteocutaneous tissue has been widely used to reconstruct the mandible. However, it is technically challenging to shape this type of grafts in such a manner that they resemble the configuration of the mandible. A 48-year-old female patient who underwent anterolateral thigh (ALT) flap coverage after a tongue cancer excision was diagnosed with a tumor recurrence during the follow-up. A wide excision mandibulectomy and mandibular reconstruction with an ALT flap and a titanium implant were performed. The prefabricated titanium implant was fixed to the condyle. Then, an ALT flap was harvested from the ipsilateral thigh and anastomosed. After confirming that the circulation of the flap was intact, the implant was fixed to the parasymphysis. On the radiograph taken after the surgery, the prosthesis was well positioned and overall facial shape was acceptable. There was no postoperative complication during the follow-up period, 1 year and 2 months. The prefabricated implant allows the restoration of facial symmetry without harvesting autologous bone and it is a safe and effective surgical option for mandibular reconstruction.

Evaluation of the inclination effect of non-splinted implants on the prosthetic behavior of overdentures in mandible edentulous patients / Evaluación del efecto de la inclinación de implantes no ferulizados sobre el comportamiento protésico de sobredentaduras en pacientes desdentados mandibulares

ABSTRACT. Introduction: the aim of this study was to evaluate the sagittal inclination of implants with respect to the occlusal plane of mandibular overdentures and their effect on the prosthetic behavior of the overdentures. Methods: 52 implants were evaluated in 26 fully mandible edentulous adults (two interforaminal implants per patient), rehabilitated with ball attachments and overdenture. Cephalometric tracing was conducted, evaluating the sagittal inclination of the implant to mandibular plane (MI), occlusal plane (OI), compensation angle (CA), and anterior facial height. The following clinical variables of prosthetic behavior were assessed: the need for prosthesis rebasing, changes in prosthetic accessories, and loosening of the prosthetic attachment. The variables were described with measurements of central tendency and dispersion. Intragroup comparisons were made with the Student's t test (p < 0.05) and correlations with the Pearson coefficient. Results: 26 patients were evaluated: 70.4% females and 29.6% males. The average age was 67.93 ± 8.6 years. The follow-up period ranged from 24 to 30 months. The average MI was 78.89 ± 10.9 degrees. There was a statistically significant correlation (r = 0.6) between MI and OI in patients who underwent a change in accessories and between MI and bone loss (r = 0.557) (p = 0.007). The average MI was higher in patients subjected to rebasing (89.70 ± 11.7 degrees), compared with those who were not subjected to rebasing (76.91 ± 9.8 degrees). A relationship with prosthetic pillar loosening could not be determined. Conclusions: the sagittal inclination of implants with respect to the occlusal plane in overdentures affects bone loss, leading to a change of accessories as well as prosthesis rebasing after two years of service.

RESUMEN. Introducción: el objetivo del presente estudio consistió en evaluar la inclinación sagital de los implantes con respecto al plano oclusal de sobredentaduras mandibulares y su efecto sobre el comportamiento protésico de las mismas. Métodos: se evaluaron 52 implantes en 26 adultos desdentados totales inferiores (dos implantes interforaminales por paciente), rehabilitados con pilares tipo bola y sobredentadura. Se realizaron trazos cefalométricos y se evaluó la inclinación sagital del implante con respecto al plano mandibular (MI), el plano oclusal (OI), el ángulo de compensación (CA) y la altura facial anterior. Se evaluaron variables clínicas de comportamiento protésico: necesidad de rebase de la prótesis, cambio de aditamentos retentivos y aflojamiento del pilar protésico. Las variables se describieron con medidas de tendencia central y dispersión. Las comparaciones intragrupales se hicieron con prueba t de Student (p < 0,05), y las correlaciones con el coeficiente de Pearson. Resultados: se evaluaron 26 pacientes: 70,4% mujeres y 29,6% hombres. La edad promedio fue de 67,93 ± 8,6 años. El rango de seguimiento fue de 24 a 30 meses. El MI promedio fue de 78,89 ± 10,9 grados. Hubo una correlación (r = 0,6) estadísticamente significativa entre MI y OI en los pacientes a quienes se les realizó cambio de aditamentos y entre MI y la pérdida ósea (r = 0,557) (p = 0,007). La MI promedio fue mayor en aquellos pacientes a quienes se les hizo rebase (89,70 ± 11,7 grados), en comparación con los que no tuvieron rebase (76,91 ±9,8 grados). No se pudo determinar la relación con el aflojamiento del pilar protésico. Conclusiones: la inclinación sagital de los implantes con respecto al plano oclusal de las sobredentaduras tiene un efecto sobre la pérdida ósea, lo que conlleva al cambio de aditamentos y rebase de la prótesis después de dos años de observación.

Single vs 2 Implants on Peri-implant Marginal Bone Level and Implant Failures in Mandibular Implant Overdentures: A Systematic Review With Meta-analysis.

BACKGROUND: As a consensus, the 2-implant supported overdentures (ODs) are considered as the first choice of treatment for the edentulous mandible. In the same context, there is increased evidence supporting the use of single-implant OD. The aim of any design is to preserve the remaining structures and allow the longevity of the treatment. OBJECTIVES: To evaluate the impact of single implant vs 2 implants on the peri-implant marginal bone loss (MBL) and number of implant failures in mandibular implant overdentures. METHODS: A literature search of electronic databases (PubMed and Cochrane) was performed up to March 2016 and complemented by hand search. Randomized clinical trials (RCTs) that evaluated MBL and number of implant failures relative to single-implant mandibular overdenture (MOD) were selected. The review and meta-analysis were performed using meta-analytic statistical package and in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. FINDINGS: Five RCTs met the inclusion criteria for systematic review and qualitative synthesis. The observation period ranged from 12 months to 5 years in the selected RCTs. The comparison included in the meta-analysis is single- vs 2-implant MODs. Pooled data revealed that single-implant MODs significantly decreased the MBL (mean difference: 0.27, 95% confidence interval: 0.20-0.34, P < .0001, I2 = 0%) and number of implant failures (risk ratio: 3.26, 95% confidence interval: 1.18-8.97), P = .02; I2 = 0%). CONCLUSIONS: Single-implant MOD was found to be better than 2-implant MOD in terms of MBL and number of implant failures. However, this result should be interpreted with caution due to limited number of analyzed studies with different loading protocols and short follow-up period.

Removable Partial Denture Using Anterior Implant-Supported Fixed Prostheses for Edentulous Patients: A Case Report

This case study was to report the possible increase in the denture retention and psychological relief using the implant-supported fixed prostheses in a completely edentulous patient. The implants were placed in the anterior portion of the mandible in a patient who had completely edentulous state following the extraction of residual abutment teeth, and consequently a distal extension removable partial denture was fabricated. The patient's adaptation and satisfaction to the new prosthesis was monitored and confirmed in terms of masticatory function and esthetics, by restoring the oral condition similar to initial status before the residual teeth extraction. After 6 months, radiographic examination confirmed that both the abutment teeth and the implants were stable and well maintained. Considering the relatively short clinical follow-up period, however, continuous long-term monitoring was required.

Accuracy of partially edentulous arch impressions obtained from different alginates and storage times

Purposes: This study aimed to assess the dimensional accuracy of five commercial alginates verified in stone casts. Methods: Each alginate impression (Cavex ColorChange, Cavex Holland BV; Jeltrate Plus, Dentsply; Hydrogum, Zhermack; Kromopan 100, Lascod; Ezact Kromm, Vigodent) was performed on partially edentulous standard stainless steel mandibular arch cast with reference points on teeth 33, 43, 37 and 47. On the stainless steel cast, the anteroposterior (33-37 and 43-47) and transverse (33-43 and 37-47) distances were measured in a stereomicroscope at 30x magnification and 0.5 µm accuracy. The distances between these points were measured three times, obtaining an average, which was analyzed statistically and compared with the distances obtained from the stone casts. For each alginate the casts were poured gypsum (n = 5) immediately and after a period of 1, 2, 3 and 5 days of the impression procedure. Results: The dimensional accuracy values of stone and stainless steel casts were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05). The results showed significant differences between the alginates; however, no differences in dimensional accuracy were found among the different storage times of alginate impression. Conclusions: It can be concluded that the alginate impressions can be stored for up to 5 days (AU)

Comparação dos sistemas de retenção para overdenture / Comparison of different attachment systems for overdenture

As próteses totais convencionais inferiores são as mais difíceis de adaptar, devido à perda óssea ser maior e consequentemente à baixa estabilidade e pouca retenção. Entretanto, com o aparecimento dos implantes osse-ointegráveis surgiram os tratamentos com próteses do tipo overdenture, as quais oferecem melhor estabilidade e retenção. O objetivo deste trabalho foi comparar os três principais tipos de sistemas de retenção para a pró¬tese overdenture encontrada na literatura. Para isso, foram realizadas pesquisas com os termos "overdenture"; "attachment", "implant-supported", "dental prosthesis", "denture" e "oral rehabilitation" nas bases de dados PubMed, Science Direct e Scielo. Os sistemas barra-clipe e esférico apresentaram semelhanças estatísticas quanto à retenção e estabilidade. Já o sistema magnético apresentou pouca retenção e baixa estabilidade

The conventional lower total prosthesis is the most difficult dental prosthesis to adapt in the patients mouth, due to bone loss be greater in this region, which consequently decreases stability and retention of the prosthe¬sis. However, the appearance of osseointegrated implants gave rise to treatments with overdenture prostheses, which offer better stability and retention to the prostheses. The aim of this study was to compare the three main types of overdenture prosthesis restraint systems found in the literature. For this research, we used the terms: "overdenture"; "attachment", "implant-supported", "dental prosthesis", "denture" and "oral rehabilitation" in the databases of PubMed, Science Direct and Scielo. The clip bar and spherical systems presented statistical similarities regarding retention and stability. Already, the magnetic system presented little retention and low stability