Morphometric predictors of lingual undercut depth in the posterior mandible and their relevance to immediate dental implant insertion: recommendations for CBCT / Predictores morfométricos de la profundidad de la «undecurt¼ lingual en la parte posterior de la mandíbula y su relevancia para la inserción inmediata de implantes dentales: recomendaciones para la CBCT

Deep lingual undercut (LU) is commonly encountered in the posterior mandible, and is considered a risk factor in dental implants. In this study we investigated the value of data extracted from OPGs in predicting LU depth. Such predictors might be valuable in reducing the chance of lingual plate perforation (LPP) by recommending CBCTs prior to dental implant insertion when deep LU is anticipated We aimed at assessing the following variables as potential predictors of LU depth: 1) alveolar process height (measured on OPGs), 2) alveolar process width (measured on CBCTs), and 3) the distance from apical region of dental alveoli to superior margin of IAN canal (measured on OPGs). 128 CBCTs and corresponding OPGs of posterior mandibles of 128 patients (70 females, 58 males; age range=18-87 years, mean age=45.8 years, SD=17.0 years) were used. Only dentate sites of lower first (LM1) and second molars (LM2) were considered. Four predictors of LU depth were found, the strongest was the ratio between alveolar process width (which could be assessed clinically) and alveolar process height as measured on OPGs (r=.454 at LM1 site, r=.592 at LM2 site). Predictors derived from OPG measurements might be valuable in anticipating LU depth and might be more valuable when combined with alveolar process width (which might be assessed clinically). We recommend considering the suggested predictors in assessing the need of CBCT prior to immediate dental implant insertion in posterior mandible.

El socavado lingual profundo (SLU) se encuentra comúnmente en la porción posterior de la mandíbula y es considerado un factor de riesgo en los implantes dentales. En este estudio, investigamos el valor de los datos extraídos de los OPG para predecir la profundidad del SLU. Dichos predictores podrían ser valiosos para reducir la posibilidad de perforación de la placa lingual (PPL) recomendando CBCT antes de la inserción del implante dental cuando se anticipa un SLU. El objetivo consistió en evaluar las siguientes variables como posibles predictores de profundidad de SLU: 1) altura del proceso alveolar (medida en OPG), 2) ancho del proceso alveolar (medido en CBCT) y 3) la distancia desde la región apical de los alvéolos dentales al margen superior del canal IAN (medido en OPG). Se utilizaron 128 CBCT y las OPG correspondientes de mandíbulas de 128 pacientes (70 mujeres, 58 hombres; rango de edad = 18-87 años, edad media = 45,8 años, SD = 17,0 años). Sólo se consideraron los sitios dentados de los primeros molares inferiores (LM1) y los segundos molares inferiores (LM2). Se encontraron cuatro predictores de profundidad de SLU, el más fuerte fue la relación entre el ancho del proceso alveolar (que podría evaluarse clínicamente) y la altura del proceso alveolar medida en OPG (r = 0,454 en el sitio LM1, r = 0,592 en el sitio LM2). Los predictores derivados de las mediciones de OPG podrían ser valiosos para anticipar la profundidad de SLU y podrían ser más valiosos cuando se combinan con el ancho del proceso alveolar (que podría evaluarse clínicamente). Recomendamos considerar los factores predictivos sugeridos para evaluar la necesidad de CBCT antes de la inserción inmediata del implante dental en la porción posterior de la mandíbula.

Lesiones del nervio dentario inferior en cirugías implantológicas del sector posterior mandibular / Inferior dental nerve injuries in implant surgeries on the posterior mandibular zone

Objetivo: se presenta este estudio para determinar el porcentaje de alteraciones nerviosas posteriores alas cirugías implantológicas del sector posterior mandibular. Pacientes y métodos: Se realizó un estudioretrospectivo de las cirugías implantológicas del sector posterior mandibular desde Enero de 2013 a Junio de 2015. Se incluyeron sólo las cirugías de rebordes cicatrizadosen brechas libres e intercalares. Resultados: Se colocaron 234 implantes en 106 pacientes en zonade premolares y molares inferiores. Se obtuvo un solo caso de alteración nerviosa post quirúrgica, determinandoun porcentaje de 0,43 por ciento (IC95: 0,08 por ciento a 2,38 por diento) por implante colocado, y un 0,94 por ciento (IC95: 0,17 por ciento a 5,15 por ciento) por paciente tratado. Esta alteración nerviosa revirtió a los 2 meses. No se registraron casos de alteraciones permanentes. Conclusión: El porcentaje de alteraciones nerviosas posteriores a cirugías implantológicasdifiere considerablemente en la literatura. Se han presentado valores en un rango de 0 a 40 por ciento.Indudablementeen una buena práctica quirúrgica, como se presenta en este estudio, los valores de alteracionesnerviosas deberían ser cercanos a cero.

Aim: this study was designed to determine the percentage of altered sensation in patients undergoing posterior mandibular endoseous implant placement. Patients and Methods: One hounded and six patients who underwent posterior mandibular implant placement, from January 2013 to June 2015, constituted thestudy group. Only surgeries performed in edentulou salveolar bone sites were included. Results: 234 implants were placed in premolar and molar areas. There was only one case of nerve injury that recovered two months after the surgery. The percentage of temporary altered sensation was 0.43% (IC95: 0.08% a 2.38%) per implant placed, and 0.94% (IC95: 0.17%a 5.15%) per patient treated. No cases of permanent altered sensation were observed. Conclusion: Thepercentage of altered nerve sensation after posterior mandibular implant placement varies considerably in the international literature. Studies have presented values ranging from 0 to 40%. By using proper treatment planning, as shown in this study, nerve injuries values should be close to zero.

A histological study of non-ceramic hydroxyapatite as a bone graft substitute material in the vertical bone augmentation of the posterior mandible using an interpositional inlay technique: A split mouth evaluation.

The aim of this study was to compare the influence of graft material (non-ceramic hydroxyapatite versus autologous bone) on bone behaviour and perform a resonance frequency analysis of implants placed in augmented sites to evaluate stability. For this study, 11 patients with bilateral edentulous areas in the mandibular posterior region were selected. Alveolar augmentation osteotomies were bilaterally (split mouth design) performed. In one hemiarch, the space generated by the osteotomy was grafted with an interpositional intra-oral autologous bone graft (control group). In the other hemiarch, the space generated by the osteotomy was grafted with an interpositional non-ceramic hydroxyapatite (ncHA) (test group). The groups were randomized. After 6 months of healing, a bone sample was retrieved from each side for histological evaluation using a trephine drill that was 2-mm in internal diameter. The implant stability quotient (ISQ) was measured by the resonance frequency immediately following implant placement at baseline and after 6 months of follow-up. Good incorporation of the graft was observed in both groups; however, in the test group, a residual-grafted material was observed. Bone density and marrow spaces were similar between groups. Correlations between the ISQ values and the histometric variables were not observed (p>0.05). The results of this trial suggest that both intra-oral autologous bone and ncHA may be elected as interpositional grafting materials to vertically augment posterior atrophic mandibles.

Stability of implants placed in augmented posterior mandible after alveolar osteotomy using resorbable nonceramic hydroxyapatite or intraoral autogenous bone: 12-month follow-up.

PURPOSE: This prospective, controlled split-mouth study evaluated the stability of dental implants placed in the augmented mandibular areas with alveolar segmental "sandwich" osteotomies using nonceramic hydroxyapatite (ncHA) or autogenous bone. MATERIAL AND METHODS: This study included 11 bilaterally partially edentulous mandibular patients in a split-mouth design. Alveolar augmentation osteotomies were performed bilaterally with interpositional ncHA graft (test group) or interpositional intraoral autogenous bone graft (control group). After 6 months of healing, four implants (two implants in each side) were placed in each patient. Forty-four implants were inserted and loaded after 6-month healing period. At 1-year follow-up, radiographic, prosthetic, and resonance frequency analysis parameters were assessed. Success criteria included absence of pain, sensitivity, suppuration, and implant mobility; absence of continuous peri-implant radiolucency; and distance between the implant shoulder and the first visible bone contact (DIB) < 2 mm. RESULTS: After a 1-year loading period, the overall implant survival rate was 95.45%, with two implant losses (one of each group). Among the surviving implants (42 out of 44), two did not fulfill the success criteria; therefore, the implant success was 90.90%. DIB was 0.71 ± 0.70 and 0.84 ± 0.72 mm for ncHA and autogenous bone grafts, respectively (p > .05). Implant stability measurements were similar between the groups during the 12-month follow-up (p > .05). CONCLUSION: Within the limits of this study, the implants placed either in sites augmented with ncHA or autogenous bone seem to represent a safe and successful procedure, at least, after 12-month follow-up.

Vertical splitting of the mandibular body as an alternative to inferior alveolar nerve lateralization.

The aim of this study was to present and evaluate a modified technique to inferior alveolar nerve lateralization (IANL) that allows the placement of longer implants in the posterior mandibular region. One hundred and forty-three consecutive patients were enrolled in this study; these patients had between 1.8 and 8mm residual crestal height above the mandibular canal. Vertical splitting of the mandibular body was performed using piezoelectric surgery followed by bone expansion and insertion of special conical implants of 10 and/or 12mm in length. Two hundred and sixty-nine osteotomies were performed and 636 implants were inserted, with a survival rate of 99% at the end of 12 months. Immediately postoperative there was an alteration of sensation in the lip/chin area in 8.5% of cases; 4.1% regained full sensation within 10-14 days, 2.6% after 8 weeks, and 0.7% had persistent paresthesia that did not affect their daily activities. Progressively increasing pain and numbness was present in 1.1%; the implants were removed 6 months postoperatively. This is a relatively simple procedure that has no limitations in clinical situations with minimal bone height. It allows for greater implant stability, and the risk of neurological disturbance is minimal.

Alveolar osteotomy associated with resorbable non-ceramic hydroxylapatite or intra-oral autogenous bone for height augmentation in posterior mandibular sites: a split-mouth prospective study.

BACKGROUND: The presence of the inferior alveolar nerve within the body of the mandible could jeopardize the placement of dental implants. Previous studies have shown that the interpositional osteotomy for posterior mandible ridge augmentation could be a predictable procedure. Nevertheless, there are few prospective, controlled, and randomized studies that evaluated this technique using different bone graft materials. PURPOSE: This prospective, controlled split-mouth study evaluated, using tomographic and Resonance Frequency Analyses (RFA), implants placed in the augmented mandibular area. MATERIAL AND METHODS: Alveolar augmentation osteotomies were performed bilaterally in 12 partially edentulous mandibular patients in a split-mouth design. The alveolar segmental osteotomies were assigned in two groups: test group, interpositional non-ceramic hydroxylapatite bone graft, and control group, interpositional intra-oral autogenous bone graft. After 6 months healing, implants were placed. The tomographic measurements of bone gain were recorded at baseline and 6 months after surgery, when the implants were placed. At 12 months after osteotomy, RFA were performed for each implant. RESULTS: The mean of bone gain 6.5 ± 2.4 mm and 7.0 ± 1.76 mm to control and test group, respectively (P > 0.05). RFA values between groups were similar at baseline and 12 months follow-up (P > 0.05). CONCLUSION: Alveolar osteotomies associated with sandwich interpositional bone graft, independently of bone graft, resulted in bone formation over a period of 12 months.