Interproximal Open Contacts Between Implant Restorations and Adjacent Teeth. Prevalence - Causes - Possible Solutions.

PURPOSE: To present the prevalence and contributing factors of interproximal contact loss (ICL) between implant restorations and adjacent teeth, and to provide recommendations for possible prevention and treatment of this complication. MATERIALS AND METHODS: The authors explored the dental literature on PubMed on ICL between implants and adjacent teeth, interproximal contacts, open contacts, teeth migration causes, facial bone formation, and facial bone changes. RESULTS: ICL between fixed implant prostheses and adjacent teeth has been reported. A literature search revealed 7 studies showing a high prevalence of ICL between implant prostheses and adjacent teeth. The literature indicates that this ICL is greater in the mesial aspect in comparison with the distal. As identified by the literature review, ICL in the maxilla ranged between 18% and 66% versus 37% to 54% in the mandible. ICL might occur as early as 3 months after prosthetic treatment. The literature review documented possible tooth migration causes, crown-related causes, and bone formation/growth-related causes of ICL. CONCLUSIONS: ICL is a common multifactorial implant complication. The clinical condition will dictate if the implant crown needs to be modified/replaced or the natural tooth needs to be restored to reestablish interproximal contact between an implant prosthesis and adjacent tooth. Periodic evaluations of interproximal contacts between implant restorations and the adjacent teeth and the use of screw-retained restorations due to ease of removal is recommended to diagnose and mitigate the problem. An orthodontic retainer or occlusal guard may help prevent ICL between the implant restoration and the adjacent tooth.

The role of parotid gland irradiation in the development of severe hyposalivation (xerostomia) after intensity-modulated radiation therapy for head and neck cancer: Temporal patterns, risk factors, and testing the QUANTEC guidelines.

BACKGROUND: The aims of this study were to investigate temporal patterns and potential risk factors for severe hyposalivation (xerostomia) after intensity-modulated radiotherapy (IMRT) for head and neck cancer (HNC), and to test the two QUANTEC (Quantitative Analysis of Normal Tissue Effects in the Clinic) guidelines. PATIENTS AND METHODS: Sixty-three patients treated at the Memorial Sloan Kettering Cancer Center between 2006 and 2015, who had a minimum of three stimulated whole mouth saliva flow measurements (WMSFM) at a median follow-up time of 11 (range: 3-24) months were included. Xerostomia was defined as WMSFM ≤25% compared to relative pre-radiotherapy. Patients were stratified into three follow-up groups: 1: <6 months; 2: 6-11 months; and 3: 12-24 months. Potential risk factors were investigated (Mann-Whitney U test), and relative risks (RRs) assessed for the two QUANTEC guidelines. RESULTS: The incidence of xerostomia was 27%, 14% and 17% at follow-up time points 1, 2 and 3, respectively. At <6 months, the mean dose to the contralateral and the ipsilateral parotid glands (Dmeancontra, Dmeanipsi) was higher among patients with xerostomia (Dmeancontra: 25 Gy vs. 15 Gy; Dmeanipsi: 44 Gy vs. 25 Gy). Patients with xerostomia had higher pre-RT WMSFM (3.5 g vs. 2.4 g), and had been treated more frequently with additional chemotherapy (93% vs. 63%; all 4 variables: p < 0.05). At 6-11 months, Dmeancontra among patients with xerostomia was higher compared to patients without (26 Gy vs. 20 Gy). The RR as specified by the one- and two-gland QUANTEC guideline was 2.3 and 1.4 for patients with <6 months follow-up time, and 2.0 and 1.2 for patients with longer follow-up (6-11 + 6-24 months). CONCLUSION: Xerostomia following IMRT peaks within six months post-radiotherapy and fades with time. Limiting the mean dose to both parotid glands (ipsilateral <25 Gy, contralateral <25 Gy) and reducing the use of chemotherapy will likely decrease the rate of xerostomia. Both QUANTEC guidelines are effective in preventing xerostomia.

The prevalence and risk factors associated with osteoradionecrosis of the jaw in oral and oropharyngeal cancer patients treated with intensity-modulated radiation therapy (IMRT): The Memorial Sloan Kettering Cancer Center experience.

OBJECTIVE: To determine the prevalence and correlation of various risk factors [radiation dose, periodontal status, alcohol and smoking] to the development of osteoradionecrosis (ORN). PATIENTS AND METHODS: The records of 1023 patients treated with IMRT for oral cavity cancer (OCC) and oropharyngeal cancer (OPC) between 2004 and 2013 were retrospectively reviewed to identify patients who developed ORN. Fisher exact tests were used to analyze patient characteristics between ORN patients with OCC and OPC. Paired Wilcoxon tests were used to compare the dose volumes to the ORN and contralateral non-ORN sites. To evaluate an association between ORN and risk factors, a case-control comparison was performed. One to 2 ORN-free patients were selected to match each ORN patient by gender, tumor site and size. General estimation equations models were used to compare the risk factors in ORN cases and matched controls. RESULTS: 44 (4.3%) patients developed ORN during a median follow-up time of 52.5months. In 82% of patients, ORN occurred spontaneously. Patients with OPC are prone to develop ORN earlier compared to patients with OCC (P=0.03). OPC patients received a higher Dmax compared to OCC patients (P=0.01). In the matched case-control analysis the significant risk factors on univariate analysis were poor periodontal status, history of alcohol use and radiation dose (P=0.03, 0.002 and 0.009, respectively) and on multivariate analysis were alcohol use and radiation dose (P=0.004 and 0.026, respectively). CONCLUSION: In our study, higher radiation dose, poor periodontal status and alcohol use are significantly related to the risk of developing ORN.

Prevalence of Interproximal Open Contacts Between Single-Implant Restorations and Adjacent Teeth.

PURPOSE: The aim of this study was to determine the prevalence of interproximal open contacts between singleimplant prostheses and adjacent teeth, as well as to provide guidelines to prevent interproximal contact loss (ICL). MATERIALS AND METHODS: This was a retrospective, cross-sectional study. One hundred twenty-eight patients (174 single-implant restorations) from Columbia University College of Dental Medicine and a private faculty clinic with a single-implant restoration in the posterior or anterior region were selected to participate in this study. Patients between the ages of 19 and 91, both male and female, were included in this pilot study. The period of evaluation after implant restoration insertion was between 3 months and 11 years. Participants were seen at random intervals to identify ICL. Interproximal contacts were evaluated with 0.07-mm-thickness dental floss and visual confirmation. Contact was considered open if floss passed without resistance from adjacent teeth. RESULTS: The results of this study revealed a significant percentage of ICL, 52.8%, between single-implant restorations and adjacent teeth; 78.2% were identified on the mesial surfaces and 21.8% on the distal surfaces. ICL was noted in 57.9% of the maxillary implant restorations and 49% of the mandibular implant restorations. Eight implant restorations in women demonstrated mesial and distal openings. Among the patients with ICL, a significant percentage, 40%, were aware of the presence of ICL and food impaction. CONCLUSION: In this study, 52.8% of implant restorations demonstrated ICL. This result dictates that ICL should be included as a prosthetic implant complication. The high prevalence of ICL is justification for proper informed consent, and associated clinical problems need to be addressed. Possible causative factors were presented, but further research is necessary to identify the causative factors for ICL. The authors suggest the use of an Essix retainer to prevent ICL between single-implant restorations and adjacent teeth. Evaluation of interproximal contact between implant restorations and the adjacent teeth should be periodically monitored.