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PubMed1988

Bisphosphonate effects on alveolar bone during rat molar drifting.

The remodeling of bone during molar drifting and cortical growth in the rat maxilla and the effects of dichloromethylene bisphosphonate (Cl2MBP) on these processes were investigated in 30 age-matched rats. A control group of six rats was killed at 10 weeks of age. Beginning at 10 weeks of age, 12 rats were treated with daily subcutaneous injections of Cl2MBP (10 mg/kg), and 12 control rats were injected daily with normal saline. Six rats of each group were killed at 12 and at 20 weeks of age. All rats were injected with fluorescent bone labels eight and one days before termination. Calcified and decalcified vertical sections through the lingual roots of maxillary molars were prepared for histomorphometry. Bone apposition rates, remodeling activity, and bone cell populations were quantified by image analysis on depository and resorptive surfaces of alveolar bone and on cortical bone surfaces. The drift rates of the first and second molars were calculated. Results showed that in control animals the drift rate of the first molar exceeded that of the second molar (p less than 0.05), supporting a previously proposed mechanism for age-dependent narrowing of interdental bone. Cl2MBP treatment decreased remodeling activity on resorptive surfaces of alveolar bone, despite a transient increase in osteoclasts. Cl2MBP also decreased the osteoblast number and bone apposition rate on depository surfaces of alveolar bone, and reduced the rate of molar drifting (p less than 0.05). However, Cl2MBP treatment had no detectable effect on osteoblast number or bone apposition on cortical bone surfaces. These results support the concept that bisphosphonates influence bone formation indirectly through a coupling mechanism which links formation with resorption.

Alveolar Process↗
PubMed2005

Narrowing of the inferior dental canal in relation to the lower third molars.

OBJECTIVES: To assess narrowing of the inferior dental canal in the lower third molar regions using computed tomography (CT) and to determine the value of radiographic markers on rotational panoramic radiographs in assessing the true relationships of the inferior dental canal. METHODS: Patients referred for CT assessment of impacted lower third molars were used in this study. The lower third molars were assessed using CT to determine the position and morphology of the inferior dental canal relative to the roots and the cortical plates. The radiographic markers on rotational panoramic radiographs were correlated with the CT findings when rotational panoramic radiographs were available. RESULTS: The patients referred had 202 lower third molars. Inferior positioning of the inferior dental canal was the most common location on CT. Narrowing of the inferior dental canal was found in relation to the lower third molars in 66.8% of cases. The chance of narrowing of the inferior dental canal as shown using CT increased when at least one of the radiographic markers, superimposition, narrowing, deviation or reduction in density was present on the rotational panoramic radiograph. Deviation of the inferior dental canal on rotational panoramic radiographs was found to be the most significant predictor of narrowing of the inferior dental canal and a close relationship to the roots, as shown in CT. CONCLUSIONS: Narrowing of the inferior dental canal is a common finding when impacted lower third molars are assessed using CT. On rotational panoramic radiographs deviation of the inferior dental canal is the best predictor of narrowing of the inferior dental canal and a close relationship to the roots.

Adolescent↗
PubMed2005

Spiral computed tomographic demonstration of C-shaped canals in mandibular second molars.

OBJECTIVES: The aim of this study was to evaluate the prevalence of C-shaped canals in single rooted mandibular second molars with spiral computed tomographic imaging in detail. METHODS: One hundred and twelve single-rooted mandibular second molar samples were selected from 491 extracted mandibular second molars. The teeth were scanned by spiral computed tomographic technique to examine canal configurations. RESULTS: The evaluation criteria of the shape of roots was based on Manning's category as round, oval and C-shaped. The prevalence of C-shaped canals was found to be 8.1% in mandibular second molars. The evaluation of the root canal configurations of C-shaped mandibular second molars with single roots (40 teeth) was based on Vertucci's classification. Vertucci type I canals were most frequently seen in C-shaped mandibular second molars (40%). Additionally, we disclosed three additional canal types. CONCLUSION: Results of this study demonstrated that high resolution visualization of the root canal shape can be achieved by spiral computed tomographic imaging.

Dental Pulp Cavity↗
PubMed1999

Management of bilaterally impacted mandibular second and third molars.

BACKGROUND: The authors present an interdisciplinary approach to treating bilateral impaction of mandibular second molars. CASE DESCRIPTION: A 22-year-old man had a bilateral deep horizontal impaction of his mandibular second molars. The mandibular third molars lay above and parallel to the second molars. After an orthodontic assessment, the authors decided to distally upright the third molars, remove them and then orthodontically reposition the second molars if they were not ankylosed. This combined orthodontic-surgical approach was successful. CLINICAL IMPLICATIONS: This case illustrates the importance of strong cooperation among various specialists to establish the optimal comprehensive treatment plan.

Adult↗
PubMed2003

Surgical uprighting and repositioning of severely impacted mandibular second molars.

BACKGROUND: Impacted second molars can create problems with esthetics, masticatory function and dental arch stability. Treatment options include surgical extraction, surgical uncovering with orthodontic-assisted eruption and surgical uprighting. CASE DESCRIPTION: The authors review the literature concerning surgical molar uprighting, and present a case in which the procedure was performed successfully to treat an impacted second molar in a female adolescent. The authors surgically repositioned a horizontal, right mandibular second molar that was partially impacted in bone. The patient was followed up for three years, during which time she was free of complications. CLINICAL IMPLICATIONS: Surgical molar uprighting has been shown to be a predictable and reliable procedure. When a molar tooth is severely impacted, surgical uprighting provides a viable option when other treatment modalities are contraindicated.

Adolescent↗
PubMed2003

The unresolved problem of the third molar: would people be better off without it?

BACKGROUND: Third molars are teeth that have little functional value and a relatively high rate of associated pain and disease. Their value as part of the dentition of modern people is dubious. TYPES OF STUDIES REVIEWED: The authors review the evolution, development, morbidity and treatment of third molars. They assess the value of third molars in the 21st century and describe the risks these teeth pose when they develop in the dentition. CONCLUSIONS: There is a mandate for the dental profession to improve health outcomes and quality of life. The prevention of third molar-related morbidity should be included in dental research efforts. The authors suggest that novel preventive methodologies be developed to alleviate the problems third molars pose. One potential methodology suggested is intentional therapeutic agenesis of this tooth. CLINICAL IMPLICATIONS: Prevention of third molar development early in life, even before tooth bud initiation, could dramatically improve health care outcomes for millions of people.

Decision Making↗
PubMed2005

Effectiveness of computerized delivery of intrasulcular anesthetic in primary molars.

BACKGROUND: Pain measures associated with computerized delivery of intrasulcular anesthestic have not been reported. The authors evaluated a computerized delivery system for intrasulcular (CDS-IS) anesthesia in primary molars. METHODS; The study population consisted of children aged 2 to 13 years who received CDS-IS injections, 159 in mandibular molars and 48 in maxillary molars. Children were treated by one of three modes of behavioral management: behavior modification (BM) only, inhalation of nitrous oxide (N2O) in addition to BM or intrarectal sedation. Variables evaluated included the subjective perception of the child's well-being before and after administration of the anesthetic, the child's pain behavior during anesthetic administration, effectiveness of the anesthetic during dental treatment, incidence of reported postoperative dental pain (PDP) and analgesic use after the CDS-IS injections. RESULTS: The effectiveness of CDS-IS anesthesia in mandibular molars was 97 percent, 92 percent, 63 percent and 71 percent for restorations, preformed stainless steel crowns, extractions and pulpal therapies, respectively (mean effectiveness, 89 percent). The effectiveness of CDS-IS anesthesia in maxillary molars was 96 percent, 50 percent, 92 percent and 78 percent, respectively (mean effectiveness, 90 percent). CDS-IS was less effective in children aged 2 to 4 years who received sedation than it was in older children. The authors found no differences between children's subjective self-reports of well-being before and after anesthetic administration, between the sexes and/or between modes of behavioral management (that is, BM or N2O). Most children exhibited low pain-related behavior during anesthetic administration, with no differences between boys and girls. The overall incidence of PDP was 31.4 percent; 64.9 percent of these patients received pain-relieving medications as a result, with no correlation to age, tooth treated, effectiveness of anesthesia or type of treatment. CONCLUSIONS: CDS-IS is effective for anesthetizing primary molars, mainly for amalgam, resin-based composite and stainless steel crown restorations.

Adolescent↗
PubMed1998

[Biomechanical analysis of arch-guided molar distalization with super-elastic nickel-titanium springs].

The typical characteristics of orthodontic devices and their effectiveness during tooth movement are of major importance for the success of orthodontic treatment and the stability of the result. To investigate this situation, two typical tooth movements were simulated experimentally using an Orthodontic Measurement and Simulation System (OMSS). These were Distalisation of an upper last molar and Distalisation of a molar including fixation of the guiding arch to a distal supporting last molar. The movements were simulated by employing various different NiTi coil compression springs and two standard steel guiding arches with the dimensions 0.016" x 0.022" and 0.017" x 0.025". The six NiTi springs differed significantly in shape and force characteristics. The eccentric application of the orthodontic force system relative to the centre of resistance brings about a tilting of the tube and arch via molar rotation. Although the forces developed by the springs are relatively constant, frictional losses result in variations in the effective orthodontic forces. With progressive distalisation, the average frictional losses varied between 50% and 80% of the spring-generated force, and frictional variations increased. Lower frictional losses were seen with a 0.016" x 0.022" guiding arch as compared with one measuring 0.017" x 0.025". In comparison with distalisation of a last molar, fixation of the arch to a third molar was associated with higher frictional losses. The interaction of the springs with the tube-guiding arch system could be so powerful that frictional losses were detected already during the initial phase of movement, and in extreme cases led to cessation of distalisation. The rate of distalisation was not affected by the forces generated by the springs. For physiological reasons, therefore, springs developing smaller forces should be used preferentially.

Biomechanical Phenomena↗
PubMed2002

Density and diameter of dentinal tubules of first and second primary human molars--comparative scanning electron microscopy study.

The aim of the present survey was to evaluate tubule density and diameter of dentin of first and second primary human molars and compare the two dental categories. These evaluations were done solely at the middle third of the crowns of twenty extracted noncarious teeth separated in two groups (first molars and second molars). The tubule diameters observed were 0. 794 microm and 1.0 microm for first and second molars, respectively (measurements done at 35-65% from the pulp-chamber walls). Regarding tubular density, the measurements indicated 17,997.594 tubules/mm2 and 25,211.317 tubules/mm2 for first and second molars, respectively. Comparisons between-groups indicated that tubule diameter and density of dentin were higher in second molars, being the difference highly significant (P<0.01).

Child↗
PubMed1991

Periodontal implications of furcation entrance dimensions in Chinese first permanent molars.

Narrow dimensions of the entrance to furcations of multi-rooted teeth can complicate the periodontal management of furcation involvements. The objectives of this study were to measure the furcation entrance dimensions of first permanent molars from Hong Kong Chinese, and to compare these dimensions with those of the blade widths of periodontal instruments generally advocated for root surface instrumentation. A total of 363 first permanent molars, of which 185 were maxillary, were examined under 1.5 x magnification. Furcation entrance dimensions were measured using calibrated test gauges ranging from 0.3 mm to 1.5 mm. Furcation entrance dimensions equal to or less than 0.75 mm (the blade width of a new Gracey curet being 0.76 mm) in maxillary first molars were found in 79% of buccal entrances, 39% of mesial entrances, and 43% of distal entrances. In mandibular first molars, entrance dimensions equal to or less than 0.75 mm were encountered in 36% and 47% of buccal and lingual furcation entrances respectively. One-half of all furcation entrance dimensions of these first molars were less than the blade width of new Gracey curets. This high prevalence of narrow furcation entrances should be considered in the periodontal management of furcation involvement of first molars in Chinese.

Asian People↗
PubMed1992

Tooth morphology following root resection procedures in maxillary first molars.

The Disto-Buccal root is the most commonly resected root in maxillary molars. This root resection procedure results in a unique environment dictated by the contours of the remaining roots and the residual furcation between them. Tooth morphology was evaluated in 50 extracted maxillary first molars after disto-buccal root resection. The following measurements were studied: 1) The maximum concavity (D) on the distal aspect of the resected molar; 2) the minimum mesio-distal dimension (d) of tooth structure between the two remaining roots; 3) the width (s) of the residual interradicular septum; and 4) the distance (p) from the pulp chamber floor to the root separation on the distal aspect of the resected molar. The mean measurements were (D) = 2.47 mm, (d) = 3.67 mm, (s) = 3.33 mm and (p) = 2.70 mm. The value of (p) was equal to or less than 3 mm in 86% of the teeth; this means that the distance from the finish line to the interradicular osseous peak is less than 2.04 mm (average biologic width), if the finish line is placed on solid tooth structure about 1 mm below the pulp floor. Six percent of the resected molars had an overall topography easily amenable to periodontal maintenance and restorative procedures with (D) less than 2 mm, (d) greater than 3 mm, (s) greater than 3 mm, and (p) greater than 3 mm. Poor root anatomy of the remaining roots after removal of the disto-buccal root in maxillary first molars may be considered as a contraindication for root resection procedures. Unfortunately, this poor topography can be ascertained only during the surgery and after removal of the disto-buccal root.

Dental Pulp Cavity↗
PubMed1993

Efficacy of 5 machining instruments in scaling of molar furcations.

The scaling efficacy of machining instruments was studied in the furcations of 100 extracted molars. The molars were divided into 5 groups with similar furcation anatomy, painted with artificial calculus, partly submerged in stone blocks, and the furcation entrances covered with a heavy rubber dam material. Ten mandibular and 10 maxillary molars were scaled by an experienced operator with each of the following instruments/inserts: ultrasonic instrument with either a prototype ball point insert or with a new pointed insert; ultrasonic instrument with a ball point insert; reciprocating hand-piece with new inserts for furcations; and a sonic scaler with a universal insert. The molar groups were coded and graded in a stereomicroscope by 2 independent examiners, and the rankings were tested with the Kruskal-Wallis test and the multiple comparisons between treatments test. The results revealed statistically significant differences between the instruments, as well as between different topographical areas of the furcations. The sonic scaler with a universal insert and the ultrasonic instrument with ball point inserts were significantly more efficient (P < 0.05) than the reciprocating handpiece with inserts in most of the areas studied. For mandibular molars, significantly better results (P < 0.05) were obtained for lingual furcation entrances than for furcation roofs. For maxillary molars, significantly better results (P < 0.05) were obtained for distal and buccal entrance areas than for furcation roofs and inside of mesial roots. The present study may give some guidance to the practitioner in choosing machining instruments for furcation cleaning as well as identifying the most difficult topographical areas to instrument.

Analysis of Variance↗
PubMed1997

Comparative in vitro effectiveness of closed root debridement with fine instruments on specific areas of mandibular first molar furcations. I. Root trunk and furcation entrance.

The purpose of this study was to compare curets with a small blade to slim ultrasonic inserts on their efficacy in removing artificial deposits from the root trunk and furcation entrance areas of mandibular molars using an in vitro model simulating a clinically closed root debridement approach. The study was conducted on 100 artificial mandibular first molars (50 right side and 50 left side) with anatomical roots. Root trunks, furcation entrances, and furcation areas of each molar were colored by a coat of black model paint. The teeth were fixed in a custom acrylic model and maintained in a firm position by modified acrylic occlusal splints. The root areas were covered with a heavy rubber dam imitating gingival tissue. The model was attached to a mannequin and mounted on a dental chair. Fifty molars (25 right, 25 left) were instrumented with the experimental curets and an equivalent number of molars with the ultrasonic inserts. The instrumentation was carried out by one experienced operator, spending 4 minutes on each molar. The instrumented areas were individually analyzed to determine the percentage of deposits remaining, using a computerized imaging routine system. One-way analysis of variance was conducted to test for differences between both types of instruments. Results revealed that the curets were significantly more efficient (P < 0.01) than the ultrasonic inserts in removing paint from both root trunks and furcation entrances. These findings should be corroborated in a clinical study to determine the potential value of the instruments tested during initial therapy or supportive care of involved mandibular furcations.

Acrylic Resins↗
PubMed2000

Effect of smoking on periodontal health in molar teeth.

BACKGROUND: It is generally accepted that the primary cause of periodontitis is bacterial infection of long duration. In addition, there are several risk factors that may increase the probability and severity of periodontitis. For example, an increased breakdown of alveolar bone has been observed in smokers compared to never-smokers. The objective of this study was to investigate the association between cigarette smoking and periodontal health, in particular, furcation involvement in molar teeth. METHODS: One hundred twenty (120) adult regular dental patients, presenting with at least 20 teeth each, third molars excluded, were evaluated. Sixty of the subjects consumed an average (+/- SD) of 16.8 +/- 3.8 cigarettes daily and had smoked for 21.4 +/- 5.7 years. The remaining subjects presented a negative history of smoking. Periodontal conditions for the molar teeth were recorded at the first and second mandibular molar buccal furcation area. RESULTS: Oral hygiene standards and dental care habits did not differ notably between smokers and never-smokers. Smokers exhibited significantly fewer molar teeth than never-smokers (2.2 +/- 1.1 versus 3.0 +/- 0.8; P<0.01). Also, smokers exhibited significantly advanced gingival recession, probing depth, clinical attachment loss, furcation involvement, and tooth mobility compared to never-smokers (P<0.01). CONCLUSIONS: The results of this study suggest that long-term cigarette smoking significantly worsens periodontal health including degree and incidence of furcation involvement in molar teeth.

Adult↗
PubMed2000

The clinical effectiveness of implants placed immediately into fresh extraction sites of molar teeth.

BACKGROUND: Studies concerning immediate implantation describe its use in the anterior and premolar regions. However, its clinical effectiveness in immediately replacing molar teeth has rarely been challenged. The purpose of this study was to evaluate the survival rate of implants placed immediately after extraction of molar teeth to support a fixed ceramo-metal prosthesis. METHODS: From 1989 to 1996, 56 immediate implants were placed in 43 patients following extraction of 51 molars; 46 molars were replaced by 1 implant and 5 molars replaced by 2 implants. All implants were restored with fixed prostheses (4 single crowns and 52 splinted). Mean follow-up period was 15 months (range, 4 to 60 months). The influence of the following parameters on implant failure was evaluated: gender, arch, smoking, pre-extraction vertical bone loss, implant length, and severity of complications between the two stages of surgery. RESULTS: The 5-year cumulative survival rate (5-year CSR) was 89%. The 5-year CSR among men was 84% compared to 93.5% among women. The maxillary 5-year CSR was 82% and the mandibular 92%. Among non-smokers (50 implants), the 5-year CSR was 90% compared to 83% among smokers (6 implants). Complications were evident in 8 (6 minor, 2 major) out of 50 non-failing implants compared to 2 (minor) of the 6 failing implants. No differences were evident in the other study variables. CONCLUSIONS: Immediate implantation in the molar region is an alternative, predictable surgical treatment. Immediate implantation in the posterior mandible has a better prognosis than in the posterior maxilla.

Adolescent↗
PubMed2006

Long-term success of implants replacing a single molar.

BACKGROUND: The aim of this study was to assess the long-term success and survival rates of implants replacing a single molar between two natural teeth and to evaluate the influence of implant characteristics on implant success. METHODS: The study was based on a consecutive cohort of 81 patients who received implants to replace a single molar between the years 1994 and 2004. Inclusion criteria for patients were having an implant replacing a molar between two natural teeth and follow-up data of at least 6 months. Data were recorded regarding the incidence of complications and success and survival rates of these implants. RESULTS: The range of follow-up was from 6 to 125 months (mean: 36 months). Smoking was reported by 18.5% of patients. The replacement of a mandibular molar was more frequent (87.7%), with 25.9% of the implants placed immediately after tooth extraction. Two implants were used to replace a single molar in seven patients (8.6%). The failure rate was 7.4% (six implants failed: three had broken necks, and three failed because of infection or bone loss). Complications included suppuration in 11.1% of implants and a pocket around the implant in two patients (2.5%). No relation was found among failure, complications, timing of implant placement, and smoking habits. CONCLUSION: A single implant can serve as a good long-term and predictable treatment modality to replace a single molar with low complication and failure rates.

Adolescent↗
PubMed1998

The radiographic determinability of the distance between the pulp horns in the permanent first and second molar teeth.

The purpose of this study was to investigate the determinability of the distance between the pulp horns (PHD) radiographically under routine clinical conditions. This study was carried out on 36 maxillary and 28 mandibular first and second molars which were extracted because of periodontal diseases. Prior to extraction two radiographs were taken from each tooth, one using the bisecting-angle technique and the other by using the bitewing technique. After the extractions, each tooth was burred on the distal and mesial approximal surfaces and pulp horns were found. The distance between the pulp horns was measured (anatomical measurement). Using bisecting-angle and bitewing radiographs, 11 clinicians measured the PHD values of each tooth (radiographic measurement). In our study the residual error in mandibular molar teeth was statistically lower when compared to maxillary molar teeth (p < 0.01). Statistically significant differences were found between anatomic and radiographic measurements (p < 0.01) in maxillary molars. No statistically significant difference was found between anatomical and bisecting-angle measurements in mandibular first and second molars. As a result, it is concluded that bisecting-angle techniques are useful in correctly determining the PHD values in mandibular molars.

Analysis of Variance↗
PubMed1994

A morphological study on the crown dimensions of the mandibular molars in Tupaia glis.

The crown dimensions of the mandibular molars in Tupaia glis were measured. All the mean values of crown diameters and areas were larger for the M1 molar than for the M2 and M3. The last two molars were more reduced in the talonid component than in the trigonid compared to the M1, and were more reduced in the buccolingual than in the mesiodistal direction. The most common molar size sequence (MSS) was M1 > M2 > M3, and this pattern was more frequently observed in the talonid component than in the trigonid. In the canonical discriminant analysis, all the cases of the M3 were discriminated correctly, but some cases of the first two molars were confused with each other. The molars size of the mandible was closely related to that of the maxilla.

Animals↗