Factor In Resorption Research Articles

Prognostic Factors for Clinical Outcomes in Autotransplantation of Teeth with Complete Root Formation: Survival Analysis for up to 12 Years

IntroductionTooth autotransplantation is a treatment option that has the potential to restore masticatory function and esthetics to edentulous spaces resulting from extracted teeth. The purpose of this study was to investigate the prognostic factors and clinical outcomes for autotransplanted teeth with complete root formation. MethodsPatients who had received tooth autotransplantation in the Department of Conservative Dentistry, Yonsei University Dental Hospital, Seoul, Korea, from July 2001 to August 2010 were electronically searched, and a total of 105 cases of autotransplanted teeth met the inclusion criteria. Tooth survival, inflammatory root resorption (IRR), ankylosis, and related prognostic factors were assessed by using the survival analysis that was based on clinical and radiographic examination. ResultsThe cumulative tooth survival rate was 68.2% at 12 years after the tooth autotransplantation. According to the Cox proportional hazard regression analysis, patient age, donor position, and extraoral time were significantly associated with tooth survival (P < .05). Donor extraction type was significantly associated with IRR (P < .05), and transplantation timing and initial stability were significantly associated with ankylosis (P < .05) ConclusionsPatients less than 45 years of age, maxillary donor teeth, and an extraoral time of less than 15 minutes were associated with significantly higher tooth survival. Surgical extraction of the donor tooth was associated with a significantly higher incidence of IRR. Immediate transplantation after the extraction of the recipient site's tooth and low initial stability were associated with a significantly lower incidence of ankylosis

La canine maxillaire incluse augmente le risque de résorption radiculaire des dents adjacentes : un problème de proximité anatomique

Our objectives were to investigate the prevalence, resorption location and extent, and potential risk factors for impacted canine-associated root resorption (ICARR) in Chinese patients, who, unlike white patients, have predominantly buccal maxillary canine impactions. Pretreatment cone-beam computed tomography scans of 170 Chinese subjects (ages, 12-30 years; mean, 14.5 years) with impacted maxillary canines (101 buccal and 69 palatal impactions) and 170 age- and sex-matched subjects without impactions were used. All cone-beam computed tomography records were evaluated in software programs by 1 rater. The prevalence, location, and extent of ICARR at the maxillary lateral incisor, central incisor, and first premolar were analyzed. To identify risk factors for ICARR, the subjects with impacted canine were divided into 2 groups (with and without root resorption). Measurements of 10 variables were individually compared between the groups and then tested together by using binary logistic regressions for each tooth. Compared with the control subjects and the side of nonimpaction, root resorption was significantly more prevalent in the canine-impaction subjects and the side of impaction (P\0.01), with overall prevalence rates of 27%, 18% and 10% at the maxillary lateral incisor, the central incisor, and the first premolar, respectively. Predominantly affecting the apical third of all teeth, ICARR, if present, reached the pulp of the maxillary lateral incisor, the central incisor, and the first premolar at rates of 36%, 57%, and 0%, respectively. Individually, variables reflecting the proximity to the impacted maxillary canine had different measurements (P\0.05) between the impaction sites (maxillary quadrants) with and without root resorption for each tooth, whereas the canine development stage factor was only significant for the maxillary central and lateral incisors. No significant difference of ICARR prevalence was found between subjects with buccal and palatal impactions. Combined, the contact relationship was the dominant predictor for ICARR at all teeth, with "in contact" (\1 mm separation) having the largest and most significant increase of root resorption likelihood compared with "out of contact" ($1 mm separation); odds ratios were 9.9, 3.7 and 5.9 for the maxillary lateral incisor, the central incisor, and the first premolar, respectively. Maxillary canine impaction increases the risk of root resorption at adjacent teeth (incisors and first premolars). Physical proximity (\1 mm) between the impacted canine and an adjacent root is the most important predictor for root resorption, and this characteristic is largely similar in Chinese patients to that in white people.

Prevention of root resorption in hypofunctional teeth by occlusal function recovery.

To clarify whether occlusal hypofunction is one of the key determinants for root resorption during tooth movement and root resorption is prevented by its recovery. The rats were randomly divided into one control and two experimental groups: hypofunctional and recovery groups. In the hypofunctional group, an anterior metal cap and bite plate were attached to the maxillary and mandibular incisors to simulate occlusal hypofunction. In the recovery group, the appliances were removed 7 weeks after their use, and the rats were allowed to bite for 4 weeks after removal. At the age of 16 weeks, the upper first molars were moved and after 0, 7, 14, and 21 days, the maxillae were resected. The resorption area was quantified morphohistologically and tartrate-resistant acid phosphatase (TRAP)-positive cells on the root surface were counted. We also examined the expressions of receptor activator of nuclear factor-κB ligand (RANKL), macrophage-colony stimulating factor (M-CSF), and interleukin (IL)-8 immunohistochemically. The amount of root resorption and the number of TRAP-positive cells were significantly greater in the hypofunctional group than in the control and recovery groups. Moreover, immunoreactivity for RANKL, M-CSF, and IL-8 was detected in the periodontal ligament and on the root surface in the hypofunctional group. Occlusal hypofunction is one of the critical factors for root resorption; however, root resorption may be prevented by recovery of occlusal function.

Influence of periodontal tissue thickness on buccal plate remodelling on immediate implants with xenograft

To evaluate the influence of gingival thickness and bone grafting on buccal bone plate remodelling after immediate implant placement in sockets with thin buccal bone, using a flapless approach. The gingiva of eight dogs was thinned at one side of the mandible, mandibular premolars were extracted without flaps, and four implants were installed on each side at 1.5 mm from the buccal bone. The sites were randomly assigned into: TG (test group) = thin gingiva; TG + GM (TG with grafting material); CG (control group) = normal gingiva; and CG + GM (CG with grafting material). After 12 weeks the dogs were sacrificed and the samples were processed for histological analysis. All animals exhibited a thin buccal bone initially. In all the experimental groups the buccal gap was filled with newly formed bone and the buccal bone level was slightly apical to the implant shoulder. There were no statistically significant differences among the groups for the histomorphometric parameters. The thickness of the buccal bone was a fundamental factor in buccal bone plate resorption, even with flapless implantation. The gingival thickness or the addition of a biomaterial in the gap did not influence the results.

Complications of cranioplasty using a bone flap sterilised by autoclaving following decompressive craniectomy.

Increasing use of decompressive craniectomies has led to a corresponding number of cranioplasties performed to replace the subsequent bone defect created. We aimed to evaluate the morbidity associated with cranioplasty using an autologous bone flap sterilised in an autoclave. We retrospectively analysed data from 149 patients who underwent cranioplasty following decompressive craniectomy during the time period January 1998 to December 2012. Autologous bone flaps were sterilised in an autoclave and stored in a refrigerator at a temperature of 8 degrees above zero until cranioplasty was performed. Complications were registered and patient data were analysed in order to identify risk factors for surgical site infection and bone flap resorption after cranioplasty. Only the patients with a follow-up period of >24 months were included in the analysis of bone flap resorption (110 patients). Surgical side infection occurred in only five patients (3.3%), whereas bone flap resorption developed in 22 patients (20%). The multivariate analysis of the presented data identified the operating time of >120 min (p = 0.0277; OR, 16.877; 95% CI, 1.364-208.906) and the presence of diabetes mellitus (p = 0.0016; OR, 54.261; 95% CI, 4.529-650.083) as independent risk factors of development of infection and the presence of ventriculo-peritoneal (VP) shunt (p < 0.0001; OR, 35.564; 95% CI, 9.962-126.960) as independent risk factor of development of the bone flap resorption. Reimplantation of the autoclaved autologous bone flap following decompressive craniectomy is a simple and cheep alternative to other techniques and is available to any institution that provides autoclaving sterilisation services. This method is associated with a low rate of surgical site infection, but with a significant rate of the bone flap resorption.

Bone Flap Resorption Following Cranioplasty after Decompressive Craniectomy: Preliminary Report.

ObjectiveResorption of autologous bone flap grafts is a known long-term complication of cranioplasty following decompressive craniectomy (DC). We analyzed our data to identify risk factors for bone flap resorption (BFR) following cranioplasty.MethodsA total of 162 patients who underwent cranioplasty following DC due to life-threatening elevated intracranial pressure between October 2003 and December 2012, were included in our investigation. Follow-up exceeded one year.ResultsBFR occurred as a long-term complication in 9 of the 162 patients (5.6%). The affected patients consisted of individuals who had undergone DC for traumatic brain injury (TBI; n=4), for subarachnoid hemorrhage (SAH; n=3), for cerebral infarction (n=1), and intracerebral hemorrhage (n=1). Logistic regression analysis identified no significant risk factors for BFR.ConclusionTBI and SAH as initial diagnoses are more often associated with BFR than other diagnoses. This finding may influence future surgical decision making, especially in patients with possible risk factors for BFR. A prospective study with a large number of patients is needed to identify potential predictors of BFR such as bone flap sterilization and preservation.

Analyses Using Micro-CT Scans and Tissue Staining on New Bone Formation and Bone Fusion According to the Timing of Cranioplasty via Frozen Autologous Bone Flaps in Rabbits : A Preliminary Report.

ObjectiveThe timing of cranioplasty and method of bone flap storage are known risk factors of non-union and resorption of bone flaps. In this animal experimental study, we evaluated the efficacy of cranioplasty using frozen autologous bone flap, and examined whether the timing of cranioplasty after craniectomy affects bone fusion and new bone formation.MethodsTotal 8 rabbits (male, older than 16 weeks) were divided into two groups of early cranioplasty group (EG, 4 rabbits) and delayed cranioplasty group (DG, 4 rabbits). The rabbits of each group were performed cranioplasty via frozen autologous bone flaps 4 weeks (EG) and 8 weeks (DG) after craniectomy. In order to obtain control data, the cranioplasty immediate after craniectomy were made on the contralateral cranial bone of the rabbits (control group, CG).The bone fusion and new bone formation were evaluated by micro-CT scan and histological examination 8 weeks after cranioplasty on both groups.ResultsIn the micro-CT scans, the mean values of the volume and the surface of new bone were 50.13±7.18 mm3 and 706.23±77.26 mm2 in EG, 53.78±10.86 mm3 and 726.60±170.99 mm2 in DG, and 31.51±12.84 mm3 and 436.65±132.24 mm2 in CG. In the statistical results, significant differences were shown between EG and CG and between DG and CG (volume : p=0.028 and surface : p=0.008). The histological results confirmed new bone formation in all rabbits.ConclusionWe observed new bone formation on all the frozen autologous bone flaps that was stored within 8 weeks. The timing of cranioplasty may showed no difference of degree of new bone formation. Not only the healing period after cranioplasty but the time interval from craniectomy to cranioplasty could affect the new bone formation.

Predisposing factors for severe incisor root resorption associated with impacted maxillary canines

Severe incisor root resorption (SIRR) associated with impacted maxillary canines is rare but has important implications. Early diagnosis and treatment are imperative. In this investigation, we aimed to identify predisposing factors for impacted canine-linked SIRR. Clinical and radiographic data of 55 consecutive patients (77 canines) with SIRR of 96 incisors were compared with data from 57 consecutive control subjects (72 canines). The studied variables were age, sex, position of the impacted canine, size of the dental follicle, and incidence of anomalous lateral incisors. Lateral incisors were more often affected than central incisors, and bilateral SIRR was common. When each variable was examined separately, SIRR was significantly associated with female sex, severely mesiodistally displaced and vertically positioned canines in the middle third of the adjacent incisor root, dental follicles wider than 2 mm, and normal lateral incisors. The multivariate statistical analysis showed that the risk for SIRR was significantly higher in female subjects (4.2 times) with enlarged dental follicles (8.3 times) and normal lateral incisors (5.8 times). SIRR should be carefully screened in female patients with enlarged dental follicles and normal lateral incisors. A greater degree of canine displacement might also be associated with SIRR.

The effects of improved metabolic risk factors on bone turnover markers after 12 weeks of simvastatin treatment with or without exercise

ObjectiveEmerging evidence supports an association between metabolic risk factors and bone turnover. Statins and exercise independently improve metabolic risk factors; however whether improvements in metabolic risk factor affects bone turnover is unknown. The purpose of the present study was to: 1) evaluate the relationship between metabolic risk factors and bone turnover; and 2) determine if improvements in metabolic risk factors after 12weeks of statin treatment, exercise or the combination affect bone turnover. MethodsFifty participants with ≥2 metabolic syndrome defining characteristics were randomly assigned to one of three groups: statin (STAT: simvastatin, 40mg/day), exercise (EX: brisk walking and/or slow jogging, 45minutes/day, 5days/week), or the combination (STAT+EX). Body composition and whole body bone mineral density were measured with dual energy X-ray absorptiometry. Serum markers of bone formation (bone specific alkaline phosphatase, BAP; osteocalcin, OC), resorption (C-terminal peptide of type I collagen, CTX) and metabolic risk factors were determined. Two-factor (time, group) repeated-measures ANCOVA was used to examine changes of metabolic risk factors and bone turnover. General linear models were used to determine the effect of pre-treatment metabolic risk factors on post-treatment bone turnover marker outcomes. ResultsParticipants with ≥4 metabolic syndrome defining characteristics had lower pre-treatment OC than those with 3 or fewer. OC was negatively correlated with glucose, and CTX was positively correlated with cholesterol. STAT or STAT+EX lowered total and LDL cholesterol. The OC to CTX ratio decreased in all groups with no other significant changes in bone turnover. Higher pre-treatment insulin or body fat predicted a greater CTX reduction and a greater BAP/CTX increase. ConclusionMetabolic risk factors were negatively associated with bone turnover markers. Short-term statin treatment with or without exercise lowered cholesterol and all treatments had a small effect on bone turnover.

Bone resorption facilitates osteoblastic bone metastatic colonization by cooperation of insulin‐like growth factor and hypoxia

Bone metastasis is a multistep process that includes cancer cell dissemination, colonization, and metastatic growth. Furthermore, this process involves complex, reciprocal interactions between cancer cells and the bone microenvironment. Bone resorption is known to be involved in both osteolytic and osteoblastic bone metastasis. However, the precise roles of the bone resorption in the multistep process of osteoblastic bone metastasis remain unidentified. In this study, we show that bone resorption plays important roles in cancer cell colonization during the initial stage of osteoblastic bone metastasis. We applied bioluminescence/X-ray computed tomography multimodal imaging that allows us to spatiotemporally analyze metastasized cancer cells and bone status in osteoblastic bone metastasis models. We found that treatment with receptor activator of factor-κB ligand (RANKL) increased osteoblastic bone metastasis when given at the same time as intracardiac injection of cancer cells, but failed to increase metastasis when given 4 days after cancer cell injection, suggesting that RANKL-induced bone resorption facilitates growth of cancer cells colonized in the bone. We show that insulin-like growth factor-1 released from the bone during bone resorption and hypoxia-inducible factor activity in cancer cells cooperatively promoted survival and proliferation of cancer cells in bone marrow. These results suggest a mechanism that bone resorption and hypoxic stress in the bone microenvironment cooperatively play an important role in establishing osteoblastic metastasis.

Autologous bone flap cranioplasty following decompressive craniectomy is combined with a high complication rate in pediatric traumatic brain injury patients

Decompressive craniectomy (DC) is a last treatment option of refractory intracranial hypertension in traumatic brain injury (TBI) patients. Replacement of the autologous bone flap is the preferred method to cover the cranial defect after brain swelling has subsided. Long term outcomes and complications after replacement of the autologous bone flap in pediatric patients were studied in comparison to young, healthy adults. Medical records of 27 pediatric patients who underwent DC and subsequent replacement of the bone flap between 1998 and 2011 were reviewed retrospectively. Patients were divided into two age groups (group 1: 18 children < 15 years; group 2:9 adolescents 15-18 years). For comparative reasons, a young adult control group of 39 patients between 18 and 30 years was additionally evaluated. With 81.8 % resorption of the bone flap, this was the major complication in young children. In up to 54.4 % of patients, a surgical revision of the osteolytic bone flap became necessary. However, in some pediatric patients, the osteolysis resolved spontaneously and further operations were not required. Probable enabling factors for bone flap resorption were young age (0-7 years), size of craniectomy, permanent shunt placement, and extent of dural opening/duraplasty. Other complications were bone flap infections, loosening of the re-inserted bone flap, and postoperative hematomas. There is an unacceptably high complication rate after reimplantation of the autologous bone following DC in pediatric TBI patients, especially in young children up to seven years of age. Artificial or synthetic cranioplasties may be considered as alternatives to initial bone flap reimplantation in the growing child. Despite the fact that DC is an effective treatment in TBI with persistent intracranial hypertension, it is important to realize that DC is not only combined with replacement of the autologous bone flap but also with a high rate of additional complications especially in pediatric patients.

The influence of the periodontal biotype on peri‐implant tissues around immediate implants with and without xenografts. Clinical and micro‐computerized tomographic study in small Beagle dogs

Soft tissues and buccal bone plate remodeling after immediate implantation in sockets with thin buccal bone, using the flapless approach with or without bone graft into the buccal gap, was compared between sites with thin and normal gingiva. Eight dogs had the gingiva of one side of the mandible thinned, the mandibular premolars were extracted without flaps, and 4 implants were installed in each side, positioned 1.5 mm from the buccal bone. The sites were randomly assigned into: TG (test group) = thin gingiva; TG + GM (TG with grafting material); CG (control group) = normal gingiva; and CG + GM (CG with grafting material). Buccal bone thickness (BBT), thickness of keratinized tissue (TKT), alveolar thickness (AT), gingival recession (GR), and probing depth (PD) were clinically evaluated. Within 12 weeks the dogs were sacrificed and the samples were analyzed by micro-computerized tomography. A thin BBT was observed in all the dogs. The presurgical procedures reduced TKT in the test group, with minimal changes of the AT. There were no statistically significant differences among the groups for the clinical parameters and the tomographic analysis showed similar linear and tri-dimensional bone reduction in all the groups. The thickness of the buccal bone was a fundamental factor in buccal bone plate resorption, even with flapless implantation. The decrease in gingival thickness or the addition of a biomaterial in the gap did not influence the results.

Risk factors and rates of bone flap resorption in pediatric patients after decompressive craniectomy for traumatic brain injury

Decompressive craniectomy with subsequent autologous cranioplasty, or the replacement of the native bone flap, is often used for pediatric patients with traumatic brain injury (TBI) who have a mass lesion and intractable intracranial hypertension. Bone flap resorption is common after bone flap replacement, necessitating additional surgery. The authors reviewed their large database of pediatric patients with TBI who underwent decompressive craniectomy followed by bone flap replacement to determine the rate of bone flap resorption and identify associated risk factors. A retrospective cohort chart review was performed to identify long-term survivors who underwent decompressive craniectomy for severe TBI with bone flap replacement from January 1, 1996, to December 31, 2011. The risk factors investigated in a univariate statistical analysis were age, sex, underlying parenchymal contusion, Glasgow Coma Scale score on arrival, comminuted skull fracture, posttraumatic hydrocephalus, bone flap wound infection, and freezer time (the amount of time the bone flap was stored in the freezer before replacement). A multivariate logistic regression model was then used to determine which of these were independent risk factors for bone flap resorption. Bone flap replacement was performed at an average of 2.1 months after decompressive craniectomy. Of the 54 patients identified (35 boys, 19 girls; mean age 6.2 years), 27 (50.0%) experienced bone flap resorption after an average of 4.8 months. Underlying parenchymal contusion, comminuted skull fracture, age ≤ 2.5 years, and posttraumatic hydrocephalus were significant, or nearly significant, on univariate analysis. Multivariate analysis identified underlying contusion (p = 0.004, OR 34.4, 95% CI 3.0-392.7), comminuted skull fractures (p = 0.046, OR 8.5, 95% CI 1.0-69.6), posttraumatic hydrocephalus (p = 0.005, OR 35.9, 95% CI 2.9-436.6), and age ≤ 2.5 years old (p = 0.01, OR 23.1, 95% CI 2.1-257.7) as independent risk factors for bone flap resorption. After decompressive craniectomy for pediatric TBI, half of the patients (50%) who underwent bone flap replacement experienced resorption. Multivariate analysis indicated young age (≤ 2.5 years), hydrocephalus, underlying contusion as opposed to a hemispheric acute subdural hematoma, and a comminuted skull fracture were all independent risk factors for bone flap resorption. Freezer time was not found to be associated with bone flap resorption.

Risk factors of aseptic bone resorption: a study after autologous bone flap reinsertion due to decompressive craniotomy

In patients who have undergone decompressive craniectomy, autologous bone flap reinsertion becomes necessary whenever the cerebral situation has consolidated. However, aseptic necrosis of the bone flap remains a concern. The aim of this study was to report possible perioperative complications in patients undergoing autologous bone flap reinsertion and to identify the risk factors that may predispose the bone flap to necrosis. All patients admitted to the authors' neurosurgical department between September 1994 and June 2011 and who received their own cryoconserved bone flap after decompressive craniectomy were studied. The grade of the bone flap necrosis was classified into 2 types. Type II bone necrosis was characterized by aseptic resorption with circumscribed or complete lysis of tabula interna and externa requiring surgical revision. To define predisposing factors, a multivariate analysis was performed using bone necrosis as the dependent variable. Among the 372 patients (mean age 48.6 years, 57.4% males) who received 414 bone flaps during the observation period, 134 (36.0%) had a diffuse traumatic brain injury, 69 (18.5%) had subarachnoid hemorrhage, 58 (15.6%) had cerebral infarction, 56 (15.1%) had extraaxial bleeding, 43 (11.6%) had intracerebral bleeding, and 12 (3.2%) had a neoplasm. Surgical relevant Type II bone flap necrosis occurred in 85 patients (22.8%) and 91 bone flaps, after a median time of 15 months (interquartile range [IQR], 10-33 months). In a multivariate analysis with Type II necrosis as the dependent variable, bone flap fragmentation with 2 (OR 3.35, 95% CI 1.59-7.01, p < 0.002) or more fragments (OR 24.00, 95% CI 10.13-56.84, p < 0.001), shunt-dependent hydrocephalus (OR 1.76, 95% CI 0.99-3.12, p = 0.04), and a younger age (OR 0.98, 95% CI 0.96-0.99, p = 0.004) was associated with a higher risk for the development of an aseptic bone flap necrosis. In patients undergoing bone flap reinsertion after craniotomy, aseptic bone necrosis is an underestimated problem during long-term follow-up. Especially in younger patients with an expected good neurological recovery and a fragmented bone flap, an initial allograft should be considered because of an increased risk for aseptic bone flap necrosis.

Predisposing factors to severe external root resorption associated to orthodontic treatment

The aim of this study was to evaluate predisposing factors among patients who developed moderate or severe external root resorption (Malmgren's grades 3 and 4), on the maxillary incisors, during fixed orthodontic treatment in the permanent dentition. Ninety-nine patients who underwent orthodontic treatment with fixed edgewise appliances were selected. Patients were divided into two groups: G1 - 50 patients with no root resorption or presenting only apical irregularities (Malmgren's grades 0 and 1) at the end of the treatment, with mean initial age of 16.79 years and mean treatment time of 3.21 years; G2 - 49 patients presenting moderate or severe root resorption (Malmgren's grades 3 and 4) at the end of treatment on the maxillary incisors, with mean initial age of 19.92 years and mean treatment time of 3.98 years. Periapical radiographs and lateral cephalograms were evaluated. Factors that could influence the occurrence of severe root resorption were also recorded. Statistical analysis included chi-square tests, Fisher's exact test and independent t tests. The results demonstrated significant difference between the groups for the variables: Extractions, initial degree of root resorption, root length and crown/root ratio at the beginning, and cortical thickness of the alveolar bone. It can be concluded that: Presence of root resorption before the beginning of treatment, extractions, reduced root length, decreased crown/root ratio and thin alveolar bone represent risk factors for severe root resorption in maxillary incisors during orthodontic treatment.

Multiple internal resorption in permanent teeth associated with hyperparathyroidism

Internal resorption has been described as a resorptive defect of internal aspect of tooth. It is caused by transformation of normal pulp tissue into granulomatous tissue with giant cells which resorb dentin. Though mostly idiopathic in origin, trauma, caries and restorative procedures have also been suggested to be contributing factors of internal resorption of pulp. Most of the internal resorption cases were found on isolated individual tooth. There are few case reports on multiple root resorptions. External root resorption have been frequently associated with systemic disorders like renal diseases hyperparathyroidism, rickets etc. A rare association of multiple internal resorption of permanent teeth (including lateral incisors, canines, premolars, sparing 2 nd and 3 rd. Permanent molars and missing 35,36, 42) with elevated levels of PTH and uric acid was evident in a 28 year old female patient who presented with fracture of crowns of permanent teeth. Though many cases related to dental manifestations of chronic renal disease and internal resorption of permanent teeth have been documented in literature, there is no evidence on association of hyperparathyroidism with multiple internal resorptions of teeth.

Maxillary canine impaction increases root resorption risk of adjacent teeth: A problem of physical proximity

Our objectives were to investigate the prevalence, resorption location and extent, and potential risk factors for impacted canine-associated root resorption (ICARR) in Chinese patients, who, unlike white patients, have predominantly buccal maxillary canine impactions. Pretreatment cone-beam computed tomography scans of 170 Chinese subjects (ages, 12-30 years; mean, 14.5 years) with impacted maxillary canines (101 buccal and 69 palatal impactions) and 170 age- and sex-matched subjects without impactions were used. All cone-beam computed tomography records were evaluated in software programs by 1 rater. The prevalence, location, and extent of ICARR at the maxillary lateral incisor, central incisor, and first premolar were analyzed. To identify risk factors for ICARR, the subjects with impacted canine were divided into 2 groups (with and without root resorption). Measurements of 10 variables were individually compared between the groups and then tested together by using binary logistic regressions for each tooth. Compared with the control subjects and the side of nonimpaction, root resorption was significantly more prevalent in the canine-impaction subjects and the side of impaction (P <0.01), with overall prevalence rates of 27%,18%, and 10% at the maxillary lateral incisor, the central incisor, and the first premolar, respectively. Predominantly affecting the apical third of all teeth, ICARR, if present, reached the pulp of the maxillary lateral incisor, the central incisor, and the first premolar at rates of 36%, 57%, and 0%, respectively. Individually, variables reflecting the proximity to the impacted maxillary canine had different measurements (P <0.05) between the impaction sites (maxillary quadrants) with and without root resorption for each tooth, whereas the canine development stage factor was only significant for the maxillary central and lateral incisors. No significant difference of ICARR prevalence was found between subjects with buccal and palatal impactions. Combined, the contact relationship was the dominant predictor for ICARR at all teeth, with "in contact" (<1 mm separation) having the largest and most significant increase of root resorption likelihood compared with "out of contact" (≥1 mm separation); odds ratios were 9.9, 3.7, and 5.9 for the maxillary lateral incisor, the central incisor, and the first premolar, respectively. Maxillary canine impaction increases the risk of root resorption at adjacent teeth (incisors and first premolars). Physical proximity (<1 mm) between the impacted canine and an adjacent root is the most important predictor for root resorption, and this characteristic is largely similar in Chinese patients to that in white people.

Residents' journal review

Residents' journal review

Risk factors associated with external apical root resorption of the maxillary incisors: a 15-year retrospective study

Abstract Aim: To determine the possible risk factors for external apical resorption (EARR) of the maxillary incisors. Methods: Panoramic radiographs of 132 orthodontic patients with a mean age of 16.9 ± 3.6 years were selected from two practice centres in Tehran. The radiographs were taken between 1990 and 2005 and 63.6% of the subjects were female. Mean, standard deviation and distribution of EARR for various variables were assessed. Prevalence significance, as well as differences between frequency distributions of clinical EARR (≥ 1.2 mm) between genders, treatment plans (extraction/ non-extraction), initial overjet and overbite magnitude, and incisor types (centrals/laterals) were evaluated by the chi-squared test. The mean resorption rates on central and lateral incisors were compared using the independent-samples t-test. Associations between EARR with the age, duration of treatment, pretreatment overjet and overbite were assessed by the Pearson’s correlation test. The reliability of the method was determined by remeasuring 117 randomly selected incisors and determining the associations between both sets of measurements with the Pearson’s correlation coefficients. Results: The prevalence of EARR, and clinical EARR (≥ 1.2 mm) were 91.8% and 44.78% respectively. The average of EARR was 1.377 ± 1.214 mm, or 8.165 ± 8.021% of pretreatment root lengths. The prevalence of clinical EARR was significantly higher in extraction cases, cases with greater initial overjet and on lateral incisors. Using the t-test, significant differences (p &lt; 0.05) were observed between the extent of resorption between genders (higher in females), treatment plans (higher in extraction cases) and incisor types (greater on lateral incisors). Longer treatment times and excessive initial overjet were correlated with higher EARR levels (p &lt; 0.05, r &lt; 0.2). Conclusions: Factors related to premolar extraction, initial ovejet size, treatment time and being female may be correlated with higher EARR. Clinically significant resorption did not occur more in females.

Physical properties of root cementum: Part 23. Effects of 2 or 3 weekly reactivated continuous or intermittent orthodontic forces on root resorption and tooth movement: A microcomputed tomography study

The force application period is a modifiable factor in root resorption. There is still ambiguity if the continuity of force application is advantageous in terms of root resorption and tooth movement. In this prospective randomized clinical trial, we compared the effects of 2 reactivation periods of controlled-intermittent and continuous forces on root resorption and tooth movement. Thirty-two patients were randomly divided into 2 groups: 2 weekly and 3 weekly reactivations. A split-mouth setup was used for the intermittent and continuous force comparisons. The intermittent force was designed with a pause of 3 days before each reactivation of the springs. A buccally directed tipping force (150 g) was generated with 0.017 × 0.025-in Beta III Titanium cantilever springs (3M Unitek, Monrovia, Calif). After the extractions, surface analysis was performed with microcomputed tomography (model 1172; SkyScan, Aartselaar, Belgium) and specially designed software (CHull2D) for direct volumetric analysis. Buccal premolar movement was also measured on the images of the study casts. Continuous forces produced more resorption than intermittent forces on the total volumes in both groups. A significant difference was found for the 3-weekly group only (P <0.01) on the cervical-mesial (P <0.01) and cervical-buccal (P <0.05) compression regions. In the 2-weekly group, differences were evident in the middle-distal (P <0.05) and middle-lingual (P <0.05) tension regions. Continuous forces produced significantly more tooth movement than did the intermittent forces for both the 2-weekly (P <0.01) and the 3-weekly (P <0.001) regimens. Significant differences were not observed between the 2 intermittent force regimens regarding root resorption and tooth movement. Intermittent force causes less root resorption and tooth movement than continuous force. Root resorption decreases irrespective of the timing of reactivation, when a pause is given. On the other hand, timing of reactivation might have critical importance on continuous force applications, since 2 weekly reactivations produced faster tooth movement with similar root resorption when compared with intermittent force.